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National Severe Storms Laboratory
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National Severe Storms Laboratory
US-NationalSevereStormsLaboratory-AltLogo.svg
National Weather Center 6-20-2006 3-48-27 PM.jpg
National Weather Center at the University of Oklahoma. The National Severe Storms Laboratory moved into this building in 2006
Agency overview

Formed
1964
Preceding Agency
National Severe Storms Project and Weather Radar Laboratory
Type
Meteorology research
Headquarters
Norman, Oklahoma
35°10′53″N 97°26′25″W
Parent department
United States Department of Commerce
Parent agency
National Centers for Environmental Prediction
Website
http://www.nssl.noaa.gov
The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory located at the National Weather Center (NWC) in Norman, Oklahoma.[1] NSSL investigates all aspects of severe weather to improve severe weather warnings and forecasts in order to save lives and reduce property damage. Research areas include weather radar, automated algorithm detection tools for use with weather radar, and basic tornado research to understand how tornadoes form.
It is one of seven NOAA Research Laboratories (RLs).[2]
NSSL scientists developed the first Doppler weather radar, and have since contributed to the development of NEXRAD (WSR-88D), as well as research mobile radar systems.
NSSL also works with the Storm Prediction Center (SPC) to help verify and improve severe weather forecasting. It also has a partnership with the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) at the University of Oklahoma that enables collaboration and participation by students and visiting scientists in performing research.[1]


Contents  [hide]
1 History
2 Organization
3 See also
4 References
5 Further reading
6 External links

History[edit]



 NSSL's first Doppler weather radar located in Norman, Oklahoma. 1970s research using this radar led to NWS NEXRAD WSR-88D radar network.


 The first tornado captured on May 24, 1973, by the NSSL Doppler weather radar and NSSL chase personnel. The tornado is here in its early stage of formation near Union City, Oklahoma
.
In 1962 a research team from the United States Weather Bureau's National Severe Storms Project (NSSP) moved from Kansas City, Missouri to Norman, Oklahoma, where the Cornell Aeronautical Laboratory had installed a 3 cm continuous-wave Doppler Weather Surveillance Radar-1957 (WSR-57) in 1956. This radar was designed to detect very high wind speeds in tornadoes, but could not determine the distance to the tornadoes. The Weather Radar Laboratory (WRL) was established in Norman in 1963. In 1964 NSSL engineers modified this radar to transmit in pulses. The pulse-Doppler radar could receive data in between each transmit pulse, eliminating the need for two antennas and solving the distance problem.[3]
In 1964 the rest of the NSSP moved to Norman, where it was reorganized and renamed as the National Severe Storms Laboratory (NSSL), to which the WRL also merged. Dr. Edwin Kessler became the first director.[3] In 1969 NSSL obtained a surplus 10-cm pulse-Doppler radar from the United States Air Force. It was used in 1973 to scan and film the complete life cycle of a tornado. By comparing the film with velocity images from the radar, the researchers found a pattern that showed the tornado beginning to form before it could be visually detected on the film. The researchers named this phenomenon the Tornado Vortex Signature (TVS).[3] 1970s research using this radar led to NWS NEXRAD WSR-88D radar network.
In 1974 the laboratory commissioned a second Doppler weather radar, named the Cimarron radar, located 15 miles (24 km) west of Oklahoma City. This enabled NSSL to perform dual Doppler experiments while scanning storms with both radars simultaneously.[3]
A deliberate decision to collocate research with operations caused the National Severe Storms Forecast Center to move from Kansas City to Norman in 1997. It changed its name to the Storm Prediction Center at the same time.[3]
In 2000 NSSL was funded to build the National Weather Radar Testbed (NWRT) facility. It is located in Norman and designed to develop and test phased array radar technology. Phased array radar is five times faster than current radars and can scan the sky in less than a minute.[3]
In 2006 NSSL moved into the new National Weather Center, 6 miles (9.7 km) south of its previous location.[3]
Organization[edit]



 NSSL's former research & development laboratory, located in Norman, Oklahoma. Photo taken about 1970.
NSSL is organized into three primary divisions:
Forecast Research & Development Division
Radar Research & Development Division
Warning Research & Development Division
NOAA named Steven Koch as Director of NSSL in February 2011.[4]
See also[edit]
European Severe Storms Laboratory (ESSL)
NEXRAD Radar Operations Center (ROC)
Storm chasing
Weather forecasting
Weather radar
References[edit]
1.^ Jump up to: a b National Oceanic and Atmospheric Administration (NOAA) National Severe Storms Laboratory. About NSSL. Retrieved April 30, 2014.
2.Jump up ^ "NOAA Research Laboratories". NOAA Office of Oceanic and Atmospheric Research. Retrieved 2014-04-26.
3.^ Jump up to: a b c d e f g "National Severe Storms Laboratory NSSL History"
4.Jump up ^ "New Director at National Severe Storms Laboratory." February 15, 2011. Retrieved April 30, 2014.
Further reading[edit]
Kessler, Edwin (1 Jan 1977). National Severe Storms Laboratory: Program and history. University of Michigan Library. ASIN B0037CF8U0.
External links[edit]
National Weather Center
NOAA employees at the National Weather Center (NWC)
 


Categories: 1964 establishments
National Weather Service
Storm
Norman, Oklahoma
Storm chasing
Weather forecasting


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Storm Prediction Center
From Wikipedia, the free encyclopedia
Jump to: navigation, search


Ambox current red.svg
 This article is outdated. Please update this article to reflect recent events or newly available information. (April 2014)
Storm Prediction Center
US-StormPredictionCenter-Logo.svg
The Storm Prediction Center logo.

Agency overview

Formed
October 1995
Preceding agencies
National Severe Storms Forecast Center (1966–1995)
 SELS (1953–1966)
Jurisdiction
Federal government of the United States
Headquarters
Norman, Oklahoma
Employees
43
Agency executive
Russell Schneider, Director
Parent agency
National Centers for Environmental Prediction
Website
www.spc.noaa.gov
The Storm Prediction Center (SPC), located in Norman, Oklahoma, is tasked with forecasting the risk of severe thunderstorms and tornadoes in the contiguous United States. The agency issues convective outlooks, mesoscale discussions, and watches as a part of this process. Convective outlooks are issued for Day 1, Day 2, Day 3, and Day 4–8, and detail the risk of severe thunderstorms and tornadoes during the given forecast period, although tornado, hail, and wind details are only available for Day 1. Days 2 and 3, as well as 4–8 used a probabilistic scale, determining the probability for a severe weather event in percent. Mesoscale discussions are issued to give information on a region that is becoming a severe weather threat and states whether a watch is likely and details thereof, as well as situations of isolated severe weather when watches are not necessary. Watches are issued when forecasters are confident that severe weather will occur, and usually precede the onset of severe weather by one hour.
The agency is also responsible for forecasting fire weather (conditions favorable for wildfires) in the contiguous US, and issues Day 1, 2, and 3–8 fire weather outlooks. These outlooks detail areas with critical or extremely critical fire conditions.
The Storm Prediction Center is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce (DoC).
The Storm Prediction Center was previously known as the National Severe Storms Forecast Center and was located in Kansas City, Missouri. In October 1995, the National Severe Storms Forecast Center relocated to Norman and was renamed the Storm Prediction Center. From the time of the move until 2006, it was co-located with the National Severe Storms Laboratory and the local Weather Forecast Office at University of Oklahoma Westheimer Airport. In 2006, they moved into the National Weather Center.


Contents  [hide]
1 History
2 Overview
3 Convective outlooks 3.1 Categories
3.2 Issuance and usage
4 Mesoscale discussions 4.1 Example
5 Weather watches 5.1 Example
6 Fire weather products
7 See also
8 References
9 External links

History[edit]
The Storm Prediction Center began in 1952 in Washington, D.C. as SELS (Severe Local Storms Unit), a special unit of forecasters in the Weather Bureau. In 1954, the unit moved to Kansas City. SELS began issuing convective outlooks in 1955, and began issuing radar summaries every three hours in 1960;[1] with the increased duties of radar summaries this unit became the National Severe Storms Forecast Center (NSSFC) in 1966.[2]
In 1968 the National Severe Storms Forecast Center began issuing status reports on watches, and in 1971 the agency made their first computerized data transmission.[1] On April 2, 1982 the first Particularly Dangerous Situation watch was issued.[1] Two new products were introduced in 1986: the Day 2 Convective Outlook and the Mesoscale Discussion.[1]
The National Severe Storms Forecast Center remained located in Kansas City, Missouri until October 1995, when it moved to Norman, Oklahoma and was renamed the Storm Prediction Center.[3] In 1998, the Center began issuing the National Fire Weather Outlook.[1] The Day 3 Convective Outlook was first issued on an experimental basis in 2000, and was made an official product in 2001.[1] From 1995 to 2006 the Storm Prediction Center was housed at University of Oklahoma Westheimer Airport,[3] in the same building as the National Severe Storms Laboratory, after which it moved to the National Weather Center.[1]
The Storm Prediction Center continues operations out of the National Weather Center building as of 2011.[4]
Overview[edit]
The Storm Prediction Center is responsible for forecasting the risk of severe weather caused by severe thunderstorms, specifically those producing tornadoes, hail 1 inch (2.5 cm) or larger, and winds 58 mph (93 km/h) or greater. The agency also forecasts hazardous winter and fire weather. It does so primarily by issuing convective outlooks, severe thunderstorm watches, tornado watches, and mesoscale discussions.[5]
There is a three-stage process in which the area, time period, and details of a severe weather forecast are refined from a broad-scale forecast of potential hazards to a more specific and detailed forecast of what hazards are expected, where they are expected to occur, and in what time frame. If warranted, forecasts will also increase in severity through this three-stage process.[5]
The Storm Prediction Center employs a total of 43 personnel, including five lead forecasters, ten mesoscale/outlook forecasters, and seven assistant mesoscale forecasters.[6]
The Storm Prediction Center is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS),[3] which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce (DoC).[7]
Many SPC forecasters and support staff are heavily involved in scientific research into severe and hazardous weather. This involves conducting applied research and writing technical papers, developing training materials, giving seminars and other presentations locally and nationwide, attending scientific conferences, and participating in weather experiments.[8]
Convective outlooks[edit]



 Day 1 Convective Outlook and Probabilistic maps issued by the Storm Prediction Center during the heart of a tornado outbreak on April 7, 2006. The top map indicates the risk of general severe weather (including large hail, damaging winds, and tornadoes), while the bottom map specifically shows the percent risk of a tornado forming within 25 miles (40 km) of any point within the enclosed area. The hatched area on the bottom map indicates a 10% or greater risk of an F2 or stronger tornado forming within 25 miles (40 km) of a point.
The Storm Prediction Center issues convective outlooks (AC) consisting of categorical and probability forecasts describing the general threat of severe convective storms over the contiguous United States for the next 6–192 hours (Day 1–Day 8). They are labeled and issued by day and are issued up to five times a day.[9]
The categorical risks are general thunderstorms (green shaded area/previously brown line before April 2011), "SEE TEXT" (black, textual label on map indicating potential for isolated severe storms or near-severe storms), "SLGT" (yellow shaded area/previously green line indicating slight risk of severe weather), "MDT" (red shaded area/previously red line indicating moderate risk of severe weather), and "HIGH" (pink shaded area/previously fuchsia line indicating high risk of severe weather). Significant severe areas (referred to as "hatched areas" because of their representation on outlook maps) refer to a threat of increased storm intensity that is of "significant severe" (F2/EF2 or stronger tornado, 2 inches (5 cm) or larger hail, or 75 mph (120 km/h) winds or greater) level.[10]
In April 2011, the SPC began issuing new graphics for categorical and probabilistic outlooks. The new format includes shading of risk areas and population, county, and interstate overlays. The colors were changed as mentioned above as well. The new shaded maps also include changes to the probability color shades on each outlook.
In 2013, the SPC also added in the Convective Outlooks a small table under the severe weather forecast map in which in indicates the total surface, estimated population number and major cities that are included with a risk area from slight risk to high risk. [11]
Public severe weather outlooks (PWO) are issued when a significant or widespread outbreak is expected, especially for tornadoes. From November to March, it can also be issued for any threat of significant tornadoes in the nighttime hours, noting the lower awareness and greater danger of tornadoes at that time of year.[12]
Categories[edit]
A slight risk day typically will mean the threat exists for scattered severe weather, including scattered wind damage or severe hail and possibly some isolated tornadoes. During the peak severe weather season, most days will have a slight risk somewhere in the United States. Isolated significant severe events are possible in some circumstances, but are generally not widespread.[9]
A moderate risk day indicates that more widespread and/or more dangerous severe weather is possible (sometimes with major hurricanes), with significant severe weather often more likely. Numerous tornadoes (including some strong tornadoes), more widespread or severe wind damage and very large/destructive hail could occur. Major events, such as large tornado outbreaks, are sometimes also possible on moderate risk days, but with greater uncertainty. Moderate risk days are not uncommon and typically occur several times a month, especially during peak season. A slight risk area typically surrounds a moderate risk area, where the threat is lower.[9]
A high risk day indicates a considerable likelihood of a major tornado outbreak or (much less often) an extreme derecho event. On these days, the potential exists for extremely severe and life-threatening weather, including widespread strong or violent tornadoes and/or very destructive straight-line winds (Hail cannot verify or produce a high risk on its own, although such a day usually involves a threat for widespread very large hail as well). Many of the most prolific severe weather days were high risk days. Such days are quite rare; a high risk is typically issued only a few times each year (see List of SPC High Risk days). High risk areas are usually surrounded by a larger moderate risk area, where uncertainty is greater or the threat is somewhat lower.[9]
The Storm Prediction Center plans to broaden this system in 2014, to add two new risk categories to the three that are already in use. The categories that are being proposed for addition are a "marginal risk" (which would replace the "SEE TEXT" contours, see below) and an "enhanced risk" (which will be used to delineate areas where severe weather will occur that would fall under the current probability criteria of an upper-end slight risk, but do not warrant a the issuance of a moderate risk). In order from least to greatest threat, these would be ranked as: marginal, slight, enhanced, moderate and high.[13][14][15] The Storm Prediction Center began asking for public comment on the proposed categorical additions to the Day 1-3 Convective Outlooks on April 21, 2014.[16]

Issuance and usage[edit]

Note: SIGNIFICANT SEVERE area needed where denoted by bold italic type – otherwise default to next lower category.
Day 1 probability to categorical outlook conversion[10]

Outlook probability
TORN
WIND
HAIL
< 2% No Severe not used not used
2% See Text not used not used
< 5% not used No Severe No Severe
5% SLGT See Text See Text
10% SLGT not used not used
15% MDT SLGT SLGT
30% HIGH SLGT SLGT
45% HIGH MDT MDT
60% HIGH HIGH MDT
Experimental Day 1 probability to categorical outlook conversion[17][18]

Outlook probability
TORN
WIND
HAIL
< 2% No Severe not used not used
2% MRGL not used not used
< 5% not used No Severe No Severe
5% SLGT MRGL MRGL
10% ENH not used not used
15% MDT SLGT SLGT
30% HIGH ENH ENH
45% HIGH MDT MDT
60% HIGH HIGH MDT
Day 2 and Day 3 [19] probability to categorical outlook conversion[10]

Outlook probability
Combined TORN, WIND, and HAIL
< 5% No Severe
5% See Text
15% SLGT
30% SLGT
45% MDT
60% HIGH
Experimental Day 2 and Day 3 probability to categorical outlook conversion[17]
 * Not used on Day 3 Convective Outlooks

Outlook probability
Combined TORN, WIND, and HAIL
< 5% No Severe
5% MRGL
15% SLGT
30% ENH
45% MDT
60%* HIGH
Day 4–8 probability to categorical outlook conversion[10]

Outlook probability
Combined TORN, WIND, and HAIL
< 30% No Area
30% Severe
Experimental Day 4–8 probability to categorical outlook conversion[20]

Outlook probability
Combined TORN, WIND, and HAIL
< 15% (none)
15% 15%
30% 30%
Convective outlooks are issued in Zulu time (also known as UTC).[10]
The categories at right refer to the risk levels for the specific severe weather event occurring within 25 miles (40 km) of any point in the delineated region. SLGT is slight risk, meaning that well organized severe thunderstorms are expected, but low in number or coverage. MDT moderate risk, indicating that greater concentration and magnitude of severe weather is expected than would be expected in a slight risk. HIGH a high risk of severe weather, and indicates that a major severe weather outbreak is expected, with a high concentration of severe weather and enhanced risk of extremely severe weather. On high risk days the potential exists for 20 or more tornadoes (with some EF2 or stronger possible) or an extreme derecho (with winds of 75 miles per hour (121 km/h) or greater possible).[10] SEE TEXT means that there is a threat for severe weather, but the threat is not high enough to warrant a slight risk.[10]
The Day 1 Convective Outlook, issued five times per day at 0600Z (valid 1200Z that day until 1200Z the following day), 1300Z and 1630Z (the "morning updates," valid until 1200Z the next day), 2000Z (the "afternoon update," valid until 1200Z the next day), and the 0100Z (the "evening update," valid until 1200Z the following day), provides a textual forecast, map of categories and probabilities, and chart of probabilities. The Day 1 is currently the only outlook to issue probabilities specifically for tornadoes, hail, or wind. It is the most descriptive and highest accuracy outlook.[9]
Day 2 outlooks, issued twice daily at 0600Z and 1730Z, refer to tomorrow's weather (1200Z–1200Z of the next calendar day; for example a day 2 outlook issued on April 12, 2100 would be valid from 1200Z April 13, 2100 through 1200Z April 14, 2100) and include only a categorical outline, textual description, and a probability graph for severe convective storms generally. Day 2 moderate risks are fairly uncommon, and a Day 2 high risk has only been issued twice (for April 7, 2006 and for April 14, 2012).[9]
Day 3 outlooks refer to the day after tomorrow, and include the same products (categorical outline, text description, and probability graph) as the Day 2 outlook. As of June 2012, the SPC forecasts general thunderstorm risk areas.[21] Higher probability forecasts are less and less likely as the forecast period increases due to lessening forecast ability farther in advance. Day 3 moderate risks are quite rare; it has been used only fourteen times since the product became operational (most recently for April 28, 2014).[9][22] To date, a Day 3 high risk has never been issued, despite existing standards for issuing risk categories allowing them.[citation needed] This is most likely because it would require both a very high degree of certainty (60%) for an event which was still two days away and a reasonable level of confidence that said severe thunderstorm outbreak would include significant severe weather (EF2+ tornadoes, hurricane-force winds, and/or egg-sized hail).
Day 4–8 outlooks are the longest-term official SPC Forecast Product, and often change significantly from day to day. This extended forecast for severe weather was an experimental product until March 22, 2007, when the Storm Prediction Center incorporated it as an official product. Areas are delineated in this forecast that have least a 30% chance of severe weather in the Day 4–8 period (equivalent to a mid-range slight risk); as forecaster confidence is not fully resolute on how severe weather will evolve more than three days out, the Day 4–8 outlook only outlines the areas in which severe thunderstorms are forecast to occur during the period, and does not utilize categorical risk areas or outline where general (non-severe) thunderstorm activity will occur.[9]
Local forecast offices of the National Weather Service, radio and television stations, and emergency planners often use the forecasts to gauge the potential severe weather threats to their areas.[9]
Generally, the convective outlook boundaries or lines – slight (yellow), moderate (red), high (purple) – will be continued as an arrow or line not filled with color if the risk enters another country (Canada or Mexico) or across waters beyond the United States coastline. This indicates that the risk for severe weather is also valid in that general area of the other side of the border or oceanic boundary.

Mesoscale discussions[edit]
SPC mesoscale discussions (MDs) once covered convection (mesoscale convective discussions [MCDs]) and precipitation (mesoscale precipitation discussions [MPDs]) but the Weather Prediction Center (WPC) now issues MPDs. MCDs generally precede a tornado watch or severe thunderstorm watch, by 1–3 hours when possible.[23] Mesoscale discussions are designed to give local forecasters an update on a region where a severe weather threat is emerging and an indication of whether a watch is likely and details thereof, as well as situations of isolated severe weather when watches are not necessary.[23] MCDs contain meteorological information on what is happening and what is expected to happen in the next few hours, and forecast reasoning in regard to weather watches.[23] Mesoscale discussions are often issued to update information on watches already issued, and sometimes when one is to be canceled. Mesoscale discussions are occasionally used as advance notice of a categorical upgrade of a scheduled convective outlook.[23]
Example[edit]



 Graphic associated with the example mesoscale discussion.[24]


MESOSCALE DISCUSSION 0685
NWS STORM PREDICTION CENTER NORMAN OK0253 PM CDT FRI MAY 04 2007AREAS AFFECTED...WRN KS...PARTS OF WRN OK/ERN TX PNHDLCONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELYVALID 041953Z - 042200ZTRENDS ARE BEING CLOSELY MONITORED FOR SIGNS OF CONVECTIVEINITIATION. ALTHOUGH TIMING IS STILL A BIT UNCERTAIN...ONE OR MORETORNADO WATCHES WILL PROBABLY BE REQUIRED LATE THIS AFTERNOON.MOISTENING SOUTHERLY LOW-LEVEL FLOW AND STRONG DAYTIME HEATING ALONGSOUTHERN HIGH PLAINS DRY LINE...INTO THE VICINITY OF WEAK SURFACELOW OVER SOUTHWEST KANSAS...IS CONTRIBUTING TO STRONGDESTABILIZATION. RUC GUIDANCE INDICATES MIXED LAYER CAPE ISINCREASING INTO THE 3000-4000 J/KG RANGE...THOUGH MID-LEVELSUBSIDENCE/SHORT WAVE RIDGING ALOFT IS CURRENTLY INHIBITINGCONVECTIVE DEVELOPMENT.HOWEVER...MID/UPPER FORCING ASSOCIATED WITH AN IMPULSE LIFTING OUTOF AMPLIFIED WESTERN TROUGH IS BEGINNING TO SHIFT EAST OF THECENTRAL/SOUTHERN ROCKIES. AND...LATEST RUC GUIDANCE SUGGESTS WEAKLOWER/MID TROPOSPHERIC COOLING HAS OCCURRED ACROSS WESTERN KANSASINTO THE TEXAS PANHANDLE ASSOCIATED WITH IMPULSE ALREADY LIFTINGNORTHWARD THROUGH THE NORTH CENTRAL HIGH PLAINS. ALTHOUGHUNCERTAINTY DOES EXISTS CONCERNING TIMING OF CONVECTIVEINITIATION...MUCH OF MODEL GUIDANCE SUGGESTS THAT THIS COULD OCCURAS EARLY AS 22-23Z. THIS SEEMS MOST PROBABLE WHERE FORCING WILL BESTRONGEST NEAR SURFACE LOW...BUT INITIATION OF WIDELY SCATTEREDSTORMS MAY QUICKLY FOLLOW SUIT.STORM DEVELOPMENT/INTENSIFICATION WILL LIKELY BE VERY RAPID ONCE CAPBREAKS. AND...LARGE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS BENEATH40-50 KT CYCLONIC WEST SOUTHWESTERLY 500 MB FLOW WILL BE FAVORABLEFOR TORNADOES...IN ADDITION TO THE RISK OF VERY LARGE HAIL.ISOLATED STRONG TORNADOES ARE POSSIBLE...PARTICULARLY AS LOW-LEVELJET STRENGTHENS NEAR/SHORTLY AFTER 04/00-01Z...KERR.. 05/04/2007ATTN...WFO...ICT...OUN...GID...DDC...GLD...LUB...AMA...
Source:[24]

Weather watches[edit]
Main articles: Tornado watch and Severe thunderstorm watch
Watches (WWs) issued by the SPC are generally less than 20,000–50,000 square miles (52,000–129,000 km2) in area and are normally preceded by a mesoscale discussion.[25] Watches are intended to be issued preceding arrival of severe weather by 1–6 hours.[25] They indicate that conditions are favorable for severe thunderstorms or tornadoes. In the case of severe thunderstorm watches organized severe thunderstorms are expected but conditions are not thought to be especially favorable for tornadoes, whereas for tornado watches conditions are thought favorable for severe thunderstorms producing tornadoes.[25] In situations where a forecaster expects a significant threat of extremely severe and life-threatening weather, a watch with special wording of "Particularly Dangerous Situation" (PDS) is subjectively issued.[26] It is occasionally issued with tornado watches, normally for the potential of major tornado outbreaks.[26] A PDS severe thunderstorm watch is very rare and is typically reserved for derecho events impacting densely populated areas.[26]
Watches are not 'warnings', where there is an immediate severe weather threat to life and property. Although severe thunderstorm and tornado warnings are ideally the next step after watches, watches cover a threat of organized severe thunderstorms over a larger area and may not always precede a warning. Warnings are issued by local National Weather Service offices, not the Storm Prediction Center, which is a national guidance center.[25]
The process of issuing a convective watch begins with a conference call from SPC to local NWS offices. If after collaboration a watch is deemed necessary, the Storm Prediction Center will issue a watch approximation product which is followed by the local NWS office issuing a specific county-based watch product. The latter product is responsible for triggering public alert messages via TV, radio stations and NOAA Weather Radio. Watches can be expanded, contracted or canceled early by local NWS offices.[25]
Example[edit]



 Graphic associated with the example watch.[27]

URGENT — IMMEDIATE BROADCAST REQUESTEDTORNADO WATCH NUMBER 232NWS STORM PREDICTION CENTER NORMAN OK955 AM CDT SAT MAY 5 2007THE NWS STORM PREDICTION CENTER HAS ISSUED ATORNADO WATCH FOR PORTIONS OFPARTS OF WESTERN AND CENTRAL KANSASPARTS OF SOUTHWEST AND CENTRAL NEBRASKAEFFECTIVE THIS SATURDAY MORNING AND EVENING FROM 955 AM UNTIL1000 PM CDT....THIS IS A PARTICULARLY DANGEROUS SITUATION...DESTRUCTIVE TORNADOES...LARGE HAIL TO 4 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 90 MPH...AND DANGEROUS LIGHTNING AREPOSSIBLE IN THESE AREAS.THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 100 STATUTEMILES EAST AND WEST OF A LINE FROM 45 MILES NORTH NORTHWEST OFBROKEN BOW NEBRASKA TO 55 MILES SOUTHWEST OF RUSSELL KANSAS. FORA COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCHOUTLINE UPDATE (WOUS64 KWNS WOU2).REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FORTORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCHAREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FORTHREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTSAND POSSIBLE WARNINGS.DISCUSSION...VERY POTENT TORNADIC SUPERCELL PATTERN IN PLACE ACROSSWATCH AREA AS AIR MASS IS EXTREMELY UNSTABLE WITH VERY FAVORABLESHEAR PROFILES. WITH LITTLE INHIBITION REMAINING ALONG E OF DRYLINE...STORMS WILL RAPIDLY BECOME SEVERE BY EARLY THIS AFTERNOON WRNKS INTO SWRN NEB. TORNADIC SUPERCELLS WILL DEVELOP WITH POTENTIALFOR LONG TRACK/VIOLENT TORNADOS. AS DRY LINE REMAINS WRN KS THRUTHE AFTERNOON...ADDITIONAL DEVELOPMENT OF TORNADIC SUPERCELLS ARELIKELY OFF THE DRY LINE THRU THE EVENING HOURS.AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAILSURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACEWIND GUSTS TO 80 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO600. MEAN STORM MOTION VECTOR 22040....HALES
Source:[27]

Fire weather products[edit]

Day 3–8 probability to categorical fire weather outlook conversion[28]

Outlook probability
CRITICAL
DRY TSTM
< 10% not used No Area
10% not used MARGINAL
< 40% No Area not used
40% MARGINAL CRITICAL
70% CRITICAL not used



 An example of a Day 1 fire outlook, issued in the midst of the October 2007 California wildfires.
The Storm Prediction Center also is responsible for issuing fire weather outlooks (FWD) for the continental United States. These outlooks are a guidance product for local, state, and federal government agencies, including local National Weather Service offices, in forecasting the potential for wildfires.[29] The outlooks issued are for Day 1, Day 2, and Days 3–8. The Day 1 product is issued at 4:00 a.m. Central time and is updated at 1700Z, and is valid from 1200Z to 1200Z the following day. The Day 2 outlook is issued at 1000Z and is updated at 2000Z for the forecast period of 1200Z to 1200Z the following day. The Day 3–8 outlook is issued at 2200Z and is valid for Days 3–8.[29]
There are four types of Fire Weather Outlook areas: "See Text", a "Critical Fire Weather Area for Wind and Relative Humidity", an "Extremely Critical Fire Weather Area for Extreme Conditions of Wind and Relative Humidity", and a "Critical Fire Weather Area for Dry Thunderstorms".[30] The outlook type depends on forecast weather conditions, severity of the predicted threat, and local climatology of a forecast region.[29] "See Text" is a label on the map for pointing out areas where fire potential is great enough to pose a limited threat, but not enough to warrant a critical area, similar to "See Text" areas in convective outlooks. Critical Fire Weather Areas for Wind and Relative Humidity are typically issued when strong winds (>20 mph) and low Relative Humidity are expected to occur where dried fuels exist, similar to a slight or moderate risk of severe weather. Critical Fire Weather Areas for Dry Thunderstorms are typically issued when widespread or numerous thunderstorms producing little wetting rain (<0.10 in) are expected to occur where dried fuels exist. Extremely Critical Fire Weather Areas for Wind and Relative Humidity are issued when very strong winds and very low RH are expected to occur with very dry fuels. Extremely Critical areas are rarely issued, similar to the very low frequency of high risk areas in convective outlooks (see List of SPC extremely critical fire days).[30]

See also[edit]
Severe weather terminology (United States)
References[edit]
1.^ Jump up to: a b c d e f g Edwards, Roger; Fred Ostby (2009). "Timeline of SELS and SPC". Storm Prediction Center. Retrieved 2010-02-02.
2.Jump up ^ Stephen F. Corfidi (August 1999). "The Birth and Early Years of the Storm Prediction Center". Weather and Forecasting (American Meteorological Society) 14 (4): 507–525. Bibcode:1999WtFor..14..507C. doi:10.1175/1520-0434(1999)014<0507:TBAEYO>2.0.CO;2. ISSN 1520-0434.
3.^ Jump up to: a b c Stephen F. Corfidi (2009-12-27). "A brief history of the Storm Prediction Center". Storm Prediction Center. National Oceanic and Atmospheric Administration. Retrieved 2010-01-31.
4.Jump up ^ Carbin, Greg; Roger Edwards; Greg Grosshans; David Imy; Mike Kay; Jay Liang; Joe Schaefer; Rich Thompson. "Frequently Asked Questions (FAQ)". Storm Prediction Center Frequently Asked Questions. Storm Prediction Center. Retrieved 2010-05-13.
5.^ Jump up to: a b Storm Prediction Center. "The Severe Storms Forecast Process: Outlook to Mesoscale Discussion to Watch to Warning". About the Storm Prediction Center. Storm Prediction Center. Retrieved 2009-12-27.
6.Jump up ^ "Storm Prediction Center Employees". spc.noaa.gov. Storm Prediction Center. Retrieved 2010-04-08.
7.Jump up ^ "NOAA's National Weather Service". weather.gov. National Weather Service. Retrieved 2010-05-13.
8.Jump up ^  This article incorporates public domain material from the Storm Prediction Center document "About the Storm Prediction Center".
9.^ Jump up to: a b c d e f g h i Novy, Chris; Roger Edwards; David Imy; Stephen Goss (2008-11-13). "Convective Outlooks". Storm Prediction Center and its Products. Storm Prediction Center. Retrieved 2009-12-27.
10.^ Jump up to: a b c d e f g Storm Prediction Center (2006-02-14). "Storm Prediction Center Day 1, 2 and 3 Convective Outlooks". National Weather Service. Retrieved 2010-01-31.
11.Jump up ^ "Jun 12, 2013 2000 UTC Day 1 Convective Outlook". Storm Prediction Center. 2013-06-12. Retrieved 2013-06-14.
12.Jump up ^ National Weather Service (2009-06-25). "Public Severe Weather Outlook". Glossary — National Oceanic and Atmospheric Administration's National Weather Service. National Weather Service. Retrieved 2010-01-31.
13.Jump up ^ Forecasters Adding New Layers of Storm Outlooks, ABC News (via the Associated Press), January 17, 2014.
14.Jump up ^ Forecasters adding layers of storm outlooks, Arkansas Democrat-Gazette (via the Associated Press), January 17, 2014.
15.Jump up ^ A better outlook: SPC revises its severe categories, WUSA, March 28, 2014.
16.Jump up ^ Experimental SPC Day 1, 2, 3 Convective Outlook Change Public Comment Page
17.^ Jump up to: a b "Experimental SPC Day 1, 2, 3 Convective Outlook Change". NOAA. April 21, 2014. Retrieved 2014-04-30.
18.Jump up ^ http://products.weather.gov/PDD/SPC_Day_1to3_Cat_Conv_Outlook.pdf
19.Jump up ^ "SCN for SPC MD Format". Nws.noaa.gov. Retrieved 2013-04-22.
20.Jump up ^ http://www.spc.noaa.gov/exper/dy4-8example/
21.Jump up ^ "Service Change Notice 12-26". National Weather Service, D.C. Headquarters. Retrieved 2013-04-13.
22.Jump up ^ "SPC Day 3 Moderate Risk for Severe Thunderstorms: Just How Rare is it?". Crh.noaa.gov. Retrieved 2012-01-22.
23.^ Jump up to: a b c d Novy, Chris; Roger Edwards; David Imy; Stephen Goss (2008-11-13). "Mesoscale Discussions". Storm Prediction Center and its Products. Storm Prediction Center. Retrieved 2009-12-27.
24.^ Jump up to: a b Kerr, Brynn (2007-05-04). "Storm Prediction Center Mesoscale Discussion 685". Mesoscale Discussion 685. Storm Prediction Center. Retrieved 2009-12-27.
25.^ Jump up to: a b c d e Novy, Chris; Roger Edwards; David Imy; Stephen Goss (2008-11-13). "Severe Weather Watches". Storm Prediction Center and its Products. Storm Prediction Center. Retrieved 2009-12-27.
26.^ Jump up to: a b c National Weather Service (2009-06-25). "PDS". Glossary — National Oceanic and Atmospheric Administration's National Weather Service. National Weather Service. Retrieved 2009-12-27.
27.^ Jump up to: a b Hales, Jack (2007-05-05). "Storm Prediction Center PDS Tornado Watch 232". PDS Tornado Watch 232. Storm Prediction Center. Retrieved 2009-12-27.
28.Jump up ^ "Storm Prediction Center Day 3–8 Fire Weather Forecast Issued on Apr 21, 2013". Spc.noaa.gov. Retrieved 2013-04-22.
29.^ Jump up to: a b c Novy, Chris; Roger Edwards; David Imy; Stephen Goss (2010-03-25). "Fire Weather Outlooks". Storm Prediction Center and its Products. Storm Prediction Center. Retrieved 2010-04-16.
30.^ Jump up to: a b  This article incorporates public domain material from the Storm Prediction Center document "Fire weather outlooks".
External links[edit]
SPC.NOAA.gov - Official Website
SPC products descriptions


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List of tornadoes and tornado outbreaks
From Wikipedia, the free encyclopedia
Jump to: navigation, search



Contents  [hide]
1 Tornado events by location 1.1 North America
1.2 Europe
1.3 Asia
1.4 Southern Hemisphere
2 Deadliest tornadoes on record
3 Tornadoes rated F5 and EF5
4 Tornado-related deaths at schools
5 Tornadoes spawned by tropical cyclones
6 Tornadoes striking the downtown central business district of major cities
7 Tornadoes by day of year
8 Tornadoes by year
9 See also
10 References
11 External links

Tornado events by location[edit]
These are some notable tornadoes, tornado outbreaks, and tornado outbreak sequences that have occurred around the globe.
1.Exact death and injury counts are not possible; especially for large events and events before 1955.
2.Prior to 1950 in the United States, only significant tornadoes are listed for the number of tornadoes in outbreaks.
3.Due to increasing detection, particularly in the U.S., numbers of counted tornadoes have increased markedly in recent decades although the number of actual tornadoes and counted significant tornadoes has not. In older events, the number of tornadoes officially counted is likely underestimated.
North America[edit]
Main article: List of North American tornadoes and tornado outbreaks
Europe[edit]
Main article: List of European tornadoes and tornado outbreaks
Asia[edit]
Main article: List of tornadoes and tornado outbreaks in Asia
Southern Hemisphere[edit]
Main article: List of Southern Hemisphere tornadoes and tornado outbreaks
1.For purposes of the list, all of Africa is included as within the Southern Hemisphere and the Arabian Peninsula is included within Southwest Asia.
Deadliest tornadoes on record[edit]
See: List of tornadoes causing 100 or more deaths
Tornadoes rated F5 and EF5[edit]
See List of F5 and EF5 tornadoes
Tornado-related deaths at schools[edit]
See List of tornado-related deaths at schools
Tornadoes spawned by tropical cyclones[edit]
See History of tropical cyclone-spawned tornadoes
Tornadoes striking the downtown central business district of major cities[edit]
See List of tornadoes striking downtown areas of large cities
Tornadoes by day of year[edit]
See List of tornadoes by calendar day
Tornadoes by year[edit]
See List of tornado events by year
See also[edit]

Portal icon Weather portal
Tornado
Tornado records
Tornado intensity and damage
Tornado climatology
List of 21st-century Canadian tornadoes and tornado outbreaks
List of derecho events
List of tropical cyclones
Misconceptions about tornadoes
References[edit]
Grazulis, Thomas P. (1993). Significant Tornadoes 1680-1991, A Chronology and Analysis of Events. St. Johnsbury, VT: The Tornado Project of Environmental Films. ISBN 1-879362-03-1
--- (1997). Significant Tornadoes Update, 1992-1995. ISBN 1-879362-04-X
--- (2001). The Tornado: Nature's Ultimate Windstorm. Norman, OK: University of Oklahoma Press. ISBN 0-8061-3258-2
National Oceanic and Atmospheric Administration, National Climatic Data Center / Storm Prediction Center. Storm Data.
External links[edit]
Significant eventsWebsites Dedicated to Specific Tornado Events (SPC, NOAA)
World Wide Tornadoes (Tornado Project)
Major Canadian Tornadoes (Environment Canada)
European Tornado Extremes (TORRO)
Tornadoes in Germany (in German)
Tornado Map (German Project / Map Worldwide)
Tornadoes in Brazil
Czech and Slovakia Tornadoes (in Czech) (Czech Hydrometeorological Institute)
Tornadoes in Italy (* in Italian)
Tornado event dataSearchable Database of All US Tornadoes From 1950-present
Preliminary storm (tornadoes, severe wind and hail) reports from June 1, 1999 to present; and severe storm climatology information (SPC)
Daily Severe Weather Report Archive from 1985-1999 (SPC)
NCDC's searchable Storm Data database
Storm Data publication (NCDC) (purchase required)
STORM NEWS and Archives (Sam Barricklow, K5kJ)
Storm Report Map (SPC storm reports overlaid on Google Maps)
European Severe Storms Laboratory (ESSL) European Severe Weather Database (ESWD)
Center of Competence for Severe Local Storms in Germany, Austria, and Switzerland (TorDACH)
European Climatology on Severe Storms (University of the Balearic Islands)
MiscellaneousOnline Severe Weather Climatology for weather radar coverage areas (SPC)
Severe Thunderstorm Climatology (NSSL)
The Tornado Project
NCDC Tornado Statistics and Data
Historical Tornado Data Archive, 1950-1999 (SPC)
Tornadoes of Bangladesh and eastern India by Jonathon D. Finch, M.S. (with additional global tornado information)
European Storm Forecast Experiment (ESTOFEX)
Skywarn Europe
Extreme Weather Source Book -- Economic and Other Societal Impacts Related to Hurricanes, Floods, Tornadoes, Lightning, and Other U.S. Weather Phenomena (University of Colorado at Boulder)
Tornado History Project Searchable US tornado database overlaid on a Google Map
Weather data archivesSevere Thunderstorm Events (SPC)
Various (NCDC)
Various (Plymouth State University)
Various (Iowa State University)
Radar and weather data (McGill University)
Satellite data (University of Wisconsin–Madison)
Upper air soundings (University of Wyoming)
 


Categories: Tornado-related lists


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Tornadoes of 2014
From Wikipedia, the free encyclopedia
Jump to: navigation, search

Tornadoes of 2014


A graph of the 2014 United States tornado count as of June 18
A graph of the 2014 United States tornado count as of June 18

Timespan January – December 2014
Maximum rated tornado EF4 tornado
Vilonia, AR on April 27
Louisville, MS on April 28
Pilger, NE on June 16
 E of Pilger, NE on June 16
Stanton, NE on June 16
Wakefield, NE on June 16
Alpena, SD on June 18

Tornadoes in US 396
Damages (US) Unknown
Fatalities (US) 44
Fatalities (worldwide) 46
Tornado seasons
2012 · 2013 · 2014 · 2015 · 2016

This page documents the tornadoes and tornado outbreaks of 2014. Strong and destructive tornadoes form most frequently in the United States, Bangladesh, and Eastern India, but they can occur almost anywhere under the right conditions. Tornadoes also appear regularly in neighboring southern Canada during the Northern Hemisphere's summer season, and somewhat regularly in Europe, Asia, and Australia.
There have been 827 tornadoes reported in the United States in 2014, of which at least 396 have been confirmed. At least 46 fatalities have been confirmed in 2014: 44 in the United States and 2 in Australia.


Contents  [hide]
1 Synopsis
2 Events 2.1 United States yearly total
3 January 3.1 January 11
3.2 January 25 (Europe)
4 February 4.1 February 20–21
5 March 5.1 March 25–29
6 April 6.1 April 6–7
6.2 April 25
6.3 April 27–30
7 May 7.1 May 10–12
7.2 May 14–16
7.3 May 22
8 June 8.1 June 3–4
8.2 June 16–18
8.3 June 30–July 1
9 July 9.1 July 8
9.2 July 15 (Australia)
9.3 July 24
10 See also
11 References
12 External links

Synopsis[edit]

Fatal tornadoes in 2014



Tornadoes of 2014 is located in USA
April 25
April 25

April 27
April 27

April 27
April 27

April 27
April 27

April 28
April 28

April 28
April 28

April 28
April 28

April 28
April 28

April 28
April 28

June 16
June 16

July 8
July 8


Magnify-clip.png Approximate touchdown location of killer tornadoes in 2014
Summary of tornadoes[1]
April 25 – North Carolina (1 death)
April 27 – Iowa (2 deaths)
April 28 – Mississippi (1 death)
April 28 – Alabama (2 deaths)
April 28 – Tennessee (2 deaths)
July 8 – New York (4 deaths)
 April 27 – Oklahoma (1 death)
April 27 – Arkansas (16 deaths)
April 28 – Mississippi (10 deaths)
April 28 – Mississippi (1 death)
June 16 – Nebraska (2 deaths)

Total Fatalities: 42
Early 2014 featured several strong cold waves that settled across the United States and kept severe weather suppressed. However, severe weather did develop on January 11 after temperatures moderated, and four EF0 tornadoes were confirmed–three in Virginia and one in Georgia. The rest of the month, along with the first half of February, were very quiet in terms of severe weather. Another intrusion of warm air allowed instability to develop in mid-February, and 41 tornadoes touched down across the lower Midwest and the Southeast U.S. on February 21 and 22. Four of these were strong enough to be rated EF2 on the Enhanced Fujita scale. The rest of February and most of March was quiet, with only weak tornadoes touching down in Arizona, Florida, and California. However, activity picked up on March 27, with several tornadoes touching down across Missouri and Iowa in association with a cold front. The general trend of low activity continued through most of April with only a few small outbreaks occurring. This trend ended with a major outbreak that started on April 27 producing multiple strong tornadoes across the Great Plains and the South, and killing 35 people.
Events[edit]
See also: List of United States tornadoes from January to March 2014, List of United States tornadoes from April to May 2014, List of United States tornadoes from June to July 2014 and List of European tornadoes in 2014
United States yearly total[edit]
Unofficial totals through July 26 (final through January 31)
Confirmed
Total Confirmed
EF0 Confirmed
EF1 Confirmed
EF2 Confirmed
EF3 Confirmed
EF4 Confirmed
EF5
399* 127 185 56 18 7 0
Note: Four tornadoes have been confirmed but not yet rated: One on April 20 and three on May 11.

January[edit]
See also: List of United States tornadoes from January to March 2014
There were 4 tornadoes reported in the United States in January, of which all 4 were confirmed.
January 11[edit]
EF0 EF1 EF2 EF3 EF4 EF5
4 0 0 0 0 0
A line of severe thunderstorms swept across the Southern United States, with four EF0 tornadoes touching down in association with these thunderstorms.[2] The first of these touched down in rural Cherokee County, Georgia, downing trees and damaging a fence.[3] The other three tornadoes occurred over southeastern Virginia, downing trees and causing minimal damage to houses. However, one tornado in the Fox Hill area caused roof damage to a church and numerous houses, ripped the roof off of a school maintenance compound, and destroyed the Fox Hill Athletic Association building.[4][5][6]



January 25 (Europe)[edit]
F0 F1 F2 F3 F4 F5
0 6 1 0 0 0
A small tornado outbreak produced 7 tornadoes across England,France and Belgium, 6 of which were F1 (T2/T3) and one an F2 (T4). The strongest tornado was an F2 (T4) that has traveled 12.8 km on the border between France and Belgium damaging the town of Halluin. 3 people were injured by the storm.
February[edit]
See also: List of United States tornadoes from January to March 2014
There were 45 tornadoes reported in the United States in February, however, 47 have been confirmed.
February 20–21[edit]
EF0 EF1 EF2 EF3 EF4 EF5
21 21 4 0 0 0



 High-end EF2 damage in Fort Payne, AL.
A large shortwave trough progressed across the northern Plains on February 20,[7] with an associated surface low-pressure area contributing to a blizzard across Michigan and Wisconsin.[8] Within the warm sector of the cyclone, modest instability and moisture, as well as sufficient forcing along a cold front,[7] initiated the development of a squall line across the Ohio River Valley and Mississippi River Valley by the afternoon. Strong wind shear led to widespread damaging wind reports in addition to over two dozen tornadoes across the Midwestern and Southern United States, four of which were rated EF2 on the Enhanced Fujita scale. The EF2s affected rural areas in Illinois near the towns of Martinsburg and Pana, damaging several farms.[9][10]
The squall line continued to push eastward into the Mid-Atlantic states on February 21, leading to numerous damaging wind reports and several tornadoes from Georgia to Maryland. A brief but strong EF2 clipped the northeast side of Fort Payne, Alabama, causing significant damage to a factory, an apartment complex, and some homes.[11] Another EF2 struck Dublin, Georgia and destroyed one home, damaged 59 others, and downed numerous trees.[12] Overall, this moderate outbreak produced 46 tornadoes and no fatalities.[13]
March[edit]
See also: List of United States tornadoes from January to March 2014
There were 25 tornadoes reported in the United States in March, of which 18 have been confirmed.
March 25–29[edit]
EF0 EF1 EF2 EF3 EF4 EF5
8 4 2 0 0 0
A low pressure system tracked across the United States, producing tornadoes across California, Missouri, and across southern portions of the Eastern Seaboard. In Northern California, several brief tornadoes touched down, uprooting trees and causing minor damage. In Northern Missouri, a supercell thunderstorm produced a strong EF2 tornado, which caused heavy roof and wall damage to a farmstead near Jameson, Missouri. Another EF2 occurred in Grundy County which heavily damaged several residences near Tindall. The storm system continued east over the next few days, producing several weak and short-lived tornadoes in Florida and North Carolina.
April[edit]
See also: List of United States tornadoes from April to May 2014
There have been 250 tornadoes reported in the United States in April, of which at least 113 have been confirmed.
April 6–7[edit]
EF0 EF1 EF2 EF3 EF4 EF5
2 4 2 0 0 0
Severe thunderstorms moved across portions of the Southern United States,[14][15] producing at least eight confirmed tornadoes. An EF2 tornado destroyed mobile homes and damaged other structures in and around Hot Coffee, Mississippi.[16] Another EF2 tornado caused significant damage in the area of Pantego, North Carolina where homes were damaged and destroyed. Two people were injured when the truck they were in was thrown 50 yards (46 m).[17]
April 25[edit]
EF0 EF1 EF2 EF3 EF4 EF5
2 3 3 1 0 0
Main article: April 2014 North Carolina tornado outbreak
In advance of a compact shortwave trough and associated cold front,[18] numerous severe thunderstorms developed across central and eastern North Carolina into southern Virginia. An EF3 tornado tracked through the Whichards Beach area, damaging or destroying 100 homes and injuring 16 people. This event marks the latest time of formation of the first EF3+ tornado in any year on record. An EF2 in Edenton resulted in a fatality, the first of the year.[19]
April 27–30[edit]
Main article: April 27–30, 2014 tornado outbreak
EF0 EF1 EF2 EF3 EF4 EF5
13 40 16 9 2 0
Numerous tornadoes ripped across parts of Mississippi, Alabama, Iowa, Nebraska, Missouri, Kansas, Oklahoma, Arkansas and Florida. A large, violent tornado struck Mayflower and Vilonia, Arkansas, on April 27 causing severe damage and killing 16 people. The tornado was rated a high-end EF4, the first violent tornado of the year.[20] Another death was confirmed earlier that evening with an EF2 tornado that moved through Quapaw, Oklahoma, and Baxter Springs, Kansas.[21] Ten people were killed on the 28th when an EF4 tornado struck Louisville, Mississippi. EF3s caused major damage and fatalities in Coxey, Alabama and Tupelo, Mississippi as well.[22] Overall, this outbreak produced 80 tornadoes and killed 35 people.[23]
May[edit]
See also: List of United States tornadoes from April to May 2014
There have been 125 tornadoes reported in the United States in May, of which at least 79 have been confirmed.
May 10–12[edit]
EF0 EF1 EF2 EF3 EF4 EF5
9 13 6 2 0 0



 Farmhouse that was leveled by a large EF3 near Sutton, NE.
A moderate outbreak of at least 31 tornadoes impacted the central United States in early May 2014. On May 10, numerous supercell thunderstorms developed across Missouri in advance of an intensifying upper-level low over the Great Basin. One supercell spawned an EF2 tornado that moved through downtown Orrick, causing significant damage but no fatalities. 80% of the structures in Orrick were damaged, and the school lost much of its roof.[24] On May 11, the upper-level low continued eastward into the Plains, providing ample wind shear for tornadoes; in preparation for the event, the Storm Prediction Center issued a Moderate risk for severe weather. Numerous thunderstorms developed across the Midwest – particularly Kansas, Nebraska, and Iowa – spawning many tornadoes. A large multiple-vortex EF3 tornado passed near the town of Sutton, Nebraska, causing considerable damage to farm properties and flattening an unanchored farmhouse. Powerful rear flank downdraft winds spawned by the parent supercell severely damaged downtown Sutton.[25] Another very large rain-wrapped EF3 wedge tornado passed near the town of Cordova, Nebraska, destroying multiple homes nearby and growing to well over a mile wide at times. The Cordova tornado eventually struck the town of Beaver Crossing, damaging virtually every structure in town before dissipating. Numerous other less significant tornadoes touched down in Nebraska that evening as well.[26] Later that night, an EF2 tornado largely destroyed a lakeside condominium building near Yale, Iowa.[27] A final EF1 tornado caused minor damage on May 12 near Eaton Township, Ohio before the outbreak came to an end.[28]
May 14–16[edit]
EF0 EF1 EF2 EF3 EF4 EF5
8 3 1 1 0 0
Severe thunderstorms moved across portions of the eastern United States with multiple reports of tornadoes.[29][30] Two significant tornadoes touched down on May 14. The first, rated EF2, damaged several homes and destroyed two barns northeast of Hopkinsville, Kentucky.[31] An EF3 tornado caused substantial damage near Cedarville, Ohio, destroying several barns and a farmhouse.[32]
May 22[edit]
EF0 EF1 EF2 EF3 EF4 EF5
0 1 0 1 0 0
An EF3 tornado moved across portions of Schenectady and Albany counties in New York. The worst damage occurred in Duanesburg, where one house was almost completely destroyed.[33] This marks the strongest tornado in the state of New York since May 31, 1998.[34] Another tornado, rated EF1, touched down near Marydel, Delaware.[35]
June[edit]
See also: List of United States tornadoes from June to July 2014
There have were 326 tornadoes reported in the United States in June, of which at least 115 were confirmed.
June 3–4[edit]
EF0 EF1 EF2 EF3 EF4 EF5
6 5 1 1 0 0
On June 3, the Storm Prediction Center issued a high risk outlook for parts of the Great Plains, mainly due to a significant risk of damaging winds and large hail. A few tornadoes occurred as well, including an EF3 that leveled a poorly constructed home near Bern, KS.[36] An EF2 caused damage to farm structures near Oakland, Iowa as well.[37] On the 4th, the system produced seven additional weak tornadoes across the Midwest, resulting in minor damage.[38]
June 16–18[edit]
EF0 EF1 EF2 EF3 EF4 EF5
12 19 12 3 5 0
Main article: June 16–18, 2014 tornado outbreak
A tornado outbreak occurred with destructive tornadoes touching down across parts of Nebraska and Iowa. The town of Pilger, Nebraska was catastrophically damaged by an EF4 tornado, with two deaths and sixteen critical injuries.[39] The Pilger tornado was one of four EF4 tornadoes produced by the same parent supercell.[40] The towns of Platteville, Wisconsin, Verona, Wisconsin, Coleridge, Nebraska, Angus, Ontario, and Wessington Springs, South Dakota all sustained major impacts from strong tornadoes as well due to this outbreak.[41][42][43]
June 30–July 1[edit]
EF0 EF1 EF2 EF3 EF4 EF5
2 23 1 0 0 0
Early in the afternoon of June 30 a complex of thunderstorms developed over Iowa and evolved into a derecho that swept east-northeast to Lake Michigan. Later that evening a second derecho developed over eastern and central Iowa and moved eastward, moving through Indiana and into western Ohio in the early morning hours of July 1. These two events produced straight-line wind damage and multiple tornadoes from Iowa to portions of Michigan and Ohio.[44] Most of the tornadoes were rated EF1, however, one tornado was determined to have caused low-end EF2 damage to a home in Traer, Iowa.[45]
July[edit]
See also: List of United States tornadoes from June to July 2014
There have been 56 tornadoes reported in the United States in July, of which at least 45 have been confirmed.
July 8[edit]
EF0 EF1 EF2 EF3 EF4 EF5
1 9 2 0 0 0
Severe thunderstorms produced damaging winds and several tornadoes across portions of the northeastern United States.[46] An EF2 tornado struck the town of Smithfield, New York, destroying several homes and killing four people. A three-story house in Smithfield was knocked off of its foundation and tumbled 150 yards (140 m) down a hillside.[47] Another EF2 tornado caused significant damage in and near New Albany, Pennsylvania.[47][48]
July 15 (Australia)[edit]
Two people were killed when a tornado struck the western suburbs of Perth, Western Australia. The men, who suffered from pre-existing medical conditions, were killed in the suburb of Beaconsfield when the storm cut power to homes, and subsequently their electronic medical equipment. The tornado was confirmed by the Bureau of Meteorology. [49]
July 24[edit]
EF0 EF1 EF2 EF3 EF4 EF5
0 1 0 0 0 0
An EF1 tornado started as a waterspout on Chesapeake Bay and struck a campground in Cherrystone, Virginia, damaging and destroying campers and cabins.[50] A couple were killed when a tree fell on their tent. Their son suffered life-threatening injuries.[51] Thirty-five others were injured as well.[50]
See also[edit]
List of tornadoes and tornado outbreaks List of F5 and EF5 tornadoes
List of North American tornadoes and tornado outbreaks
List of tornadoes striking downtown areas
Fujita scale
Enhanced Fujita scale
References[edit]
1.Jump up ^ "Annual U.S. Killer Tornado Statistics". Storm Prediction Center. National Oceanic and Atmospheric Administration. May 6, 2014. Retrieved May 6, 2014.
2.Jump up ^ "20140111's Storm Reports (1200 UTC - 1159 UTC)". Storm Prediction Center. National Oceanic and Atmospheric Administration. January 11, 2014. Retrieved January 12, 2014.
3.Jump up ^ "Severe Weather Follows Cold Blast". National Weather Service Office in Peachtree City, Georgia. National Oceanic and Atmospheric Administration. January 12, 2014. Retrieved January 12, 2014.
4.Jump up ^ "Tornado Confirmed West Of Smithfield VA". National Weather Service Office in Wakefield, Virginia. National Oceanic and Atmospheric Administration. January 12, 2014. Retrieved January 20, 2014.
5.Jump up ^ "Tornado Confirmed Southeast Of Isle Of Wight Courthouse". National Weather Service Office in Wakefield, Virginia. National Oceanic and Atmospheric Administration. January 12, 2014. Retrieved January 20, 2014.
6.Jump up ^ "Tornado Confirmed In Hampton Virginia". National Weather Service Office in Wakefield, Virginia. National Oceanic and Atmospheric Administration. January 12, 2014. Retrieved January 20, 2014.
7.^ Jump up to: a b Chris Broyles (February 20, 2014). "Feb 20, 2014 1630 UTC Day 1 Convective Outlook". Storm Prediction Center. National Oceanic and Atmospheric Administration. Retrieved February 21, 2014.
8.Jump up ^ "Blizzard-Winter Storm Of February 20-21st, 2014". National Weather Service office in La Crosse, Wisconsin. National Oceanic and Atmospheric Administration. February 21, 2014. Retrieved February 21, 2014.
9.Jump up ^ "NWS Damage Survey For 02/20/2014 Tornado Event". National Weather Service Office in St. Louis, Missouri. National Oceanic and Atmospheric Administration. February 21, 2014. Retrieved February 22, 2014.
10.Jump up ^ "NWS Lincoln Damage Assessment Results for 2/20 Tornado event". National Weather Service Office in Central Illinois. National Oceanic and Atmospheric Administration. February 21, 2014. Retrieved February 22, 2014.
11.Jump up ^ "Severe Weather Event 02/20/2014 - 02/21/2014". National Weather Service Office in Huntsville, Alabama. National Oceanic and Atmospheric Administration. February 22, 2014. Retrieved February 22, 2014.
12.Jump up ^ "Severe Weather Hits North and Central Georgia". National Weather Service Office in Peachtree City, Georgia. National Oceanic and Atmospheric Administration. February 22, 2014. Retrieved February 22, 2014.
13.Jump up ^ "20140220's Storm Reports (1200 UTC - 1159 UTC)". Storm Prediction Center. National Oceanic and Atmospheric Administration. February 20, 2014. Retrieved February 21, 2014.
14.Jump up ^ "20140406's Storm Reports (1200 UTC - 1159 UTC)". Storm Prediction Center. National Oceanic and Atmospheric Administration. April 7, 2014. Retrieved April 8, 2014.
15.Jump up ^ "20140407's Storm Reports (1200 UTC - 1159 UTC)". Storm Prediction Center. National Oceanic and Atmospheric Administration. April 7, 2014. Retrieved April 8, 2014.
16.Jump up ^ "April 7, 2014 Covington County Tornado". National Weather Service Office in Jackson, Mississippi. Retrieved 9 April 2014.
17.Jump up ^ "April 7, 2014 Belhaven/Pantego Tornado - EF2". National Weather Service Office in Newport/Morehead. North Carolina. Retrieved 9 April 2014.
18.Jump up ^ Rich L. Thompson; Andy R. Dean (April 25, 2014). "April 25, 2014 1630 UTC Day 1 Convective Outlook". Storm Prediction Center. National Oceanic and Atmospheric Administration. Retrieved April 26, 2014.
19.Jump up ^ "EF3 Tornado Confirmed; 16 People Injured, Some 100 Homes Damaged In Beaufort County". WITN News. WITN News. April 26, 2014. Retrieved April 26, 2014.
20.Jump up ^ "Tornadoes/Flooding on April 27-28, 2014". National Weather Service office in Little Rock, Arkansas. Retrieved 30 April 2014.
21.Jump up ^ "Event Summary - 27 April 2014 Quapaw and Octavia Tornado Event". National Weather Service office in Tulsa, Oklahoma. Retrieved 30 April 2014.
22.Jump up ^ "Final Update: April 28, 2014 Mid-South Storm Surveys". NWS Memphis, TN. NOAA. Retrieved May 4, 2014.
23.Jump up ^ "Louisville (Leake/Neshoba/Attala/Winston County) EF-4 Tornado". National Weather Service Office in Jackson, Mississippi. Retrieved 30 April 2014.
24.Jump up ^ Washington, Brenda (May 10, 2014). "Orrick begins cleanup after devastating tornado". KMBC.com. KMBC. Retrieved May 22, 2014.
25.Jump up ^ "Mother's Day - May 11, 2014". NWS. NOAA. June 1, 2014. Retrieved June 3, 2014.
26.Jump up ^ http://www.crh.noaa.gov/images/oax/news/MothersDayTornadoes2014.pdf
27.Jump up ^ http://www.crh.noaa.gov/images/dmx/StormSurveys/2014/05-11_Panorama/Survey_Results.pdf
28.Jump up ^ http://www.weather.gov/cle/event_20140512_Tornado
29.Jump up ^ "SPC Storm Reports for 05/14/14". Storm Prediction Center. Retrieved 24 May 2014.
30.Jump up ^ "SPC Storm Reports for 05/15/14". Storm Prediction Center. Retrieved 24 May 2014.
31.Jump up ^ "NWS Damager Survey for 05/14/14 Tornado Event in Christian County, Kentucky". National Weather Service Office in Paducah, Kentucky. Retrieved 24 May 2014.
32.Jump up ^ "May 14, 2014 Tornado near Cedarville, OH". National Weather Service Office in Wilmington, Ohio. Retrieved 24 May 2014.
33.Jump up ^ "May 23, 2014 Tornado Survey". National Weather Service Office in Albany, New York. Retrieved 24 May 2014.
34.Jump up ^ "Custom Search Results". Tornado History Project. Retrieved 24 May 2014.
35.Jump up ^ "Tornado Confirmed near Marydel in Kent County, Delaware". National Weather Service Office in Mount Holly, New Jersey. Retrieved 24 May 2014.
36.Jump up ^ "June 3, 2014 Bern Tornado". NWS Topeka, KS. NOAA. June 10, 2014. Retrieved June 10, 2014.
37.Jump up ^ "EF2 Tornado Confirmed Near Oakland, IA". NWS Omaha, NE. NOAA. June 10, 2014. Retrieved June 10, 2014.
38.Jump up ^ "20140604's Storm Reports (1200 UTC - 1159 UTC)". Storm Prediction Center. National Oceanic and Atmospheric Administration. June 6, 2014. Retrieved June 6, 2014.
39.Jump up ^ Tornado hits Pilger, looks like 'a war zone'
40.Jump up ^ http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=oax&storyid=102897&source=2
41.Jump up ^ http://www.spc.noaa.gov/climo/reports/140616_rpts.html
42.Jump up ^ http://www.spc.noaa.gov/climo/reports/140617_rpts.html
43.Jump up ^ http://www.spc.noaa.gov/climo/reports/140618_rpts.html
44.Jump up ^ "Two Separate Derecho Events on June 30, 2014". National Weather Service Office in Chicago Illinois. Retrieved 26 July 2014.
45.Jump up ^ "NWS Damage Survey for June 30 2014 Tornado Event". National Weather Service Office in Des Moines, Iowa. Retrieved 2 July 2014.
46.Jump up ^ "20140708's Storm Reports (1200 UTC - 1159 UTC)". Storm Prediction Center. National Oceanic and Atmospheric Administration. July 10, 2014. Retrieved July 26, 2014.
47.^ Jump up to: a b "Severe Storms July 8, 2014". National Weather Service Office in Binghamton, New York. Retrieved 26 July 2014.
48.Jump up ^ "Tornado Confirmed Near 3 NW Dushore in Sullivan County Pennsylvania". National Weather Service in State College, Pennsylvania. Retrieved 26 July 2014.
49.Jump up ^ http://www.heraldsun.com.au/news/breaking-news/bom-confirms-tornado-in-perths-south/story-fni0xqi4-1226988611249
50.^ Jump up to: a b "Northampton County Virginia Tornado Survey Results". National Weather Service Office in Wakefield, Virginia. Retrieved 25 July 2014.
51.Jump up ^ "2 dead, 1 critical as tornado hits Virginia campground". USA Today. Retrieved 26 July 2014.
External links[edit]


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Tornado preparedness
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 This article contains instructions, advice, or how-to content. The purpose of Wikipedia is to present facts, not to train. Please help improve this article either by rewriting the how-to content or by moving it to Wikiversity, Wikibooks or Wikivoyage (January 2013)
The term "tornado preparedness" refers to safety precautions made before the arrival of and during a tornado. Historically, the steps taken have varied greatly, depending on location, or time remaining before a tornado was expected. For example, in rural areas, people might prepare to enter an external storm cellar, in case the main building collapses, and thereby allow exit without needing rescue from the main building as in urban areas. Because tropical storms have spawned many tornadoes, hurricane preparations also involve tornadoes. The term "tornado preparedness" has been used by government agencies, emergency response groups, schools,[1] insurance companies, and others.


Contents  [hide]
1 Understanding the dangers
2 Steps when expecting storms to arrive
3 Actions taken during tornadoes
4 Long-term preparations
5 Medical preparations
6 Tornado drills 6.1 Tornado drills by state
7 See also
8 References
9 External links

Understanding the dangers[edit]
Preparedness involves knowing the major dangers to avoid. Some tornadoes are the most violent storms in nature.[2] Tornadoes have varied in strength, and some tornadoes have been mostly invisible due to a lack of loose dirt or debris in the funnel cloud.[2] Spawned from severe thunderstorms, tornadoes have caused fatalities and devastated neighborhoods within seconds of arrival.



 A tornado with no obvious funnel from the upper clouds, although the rotating dust cloud indicates strong winds at the surface.
A tornado operates as a rotating, funnel-shaped cloud that extends downward from a thunderstorm, to the ground, with swirling winds which have reached 300 miles per hour (480 km/h).[2] The wind speed might be difficult to imagine: traveling the length of a U.S. football field within 1 second[3] (over 130 meters or 430 feet per second). Damage paths have been in excess of one-mile wide (1.6 km) and 50 miles long (80 km).[2]
Not all tornadoes are easily seen. A tornado funnel can be transparent until reaching an area with loose dirt and debris.[2] Also, some tornadoes have been seen against sunlit areas, but rain or nearby low-hanging clouds has obscured other tornadoes. Occasionally, tornadoes have developed so suddenly, so rapidly, that little, if any, advance warning was possible.[2]
Before a tornado strikes an area, the wind has been known to die down and the air to become very still.[2][dubious – discuss] A cloud of debris has sometimes marked the bottom of a tornado even when the funnel was not visible. Tornadoes typically occur along the trailing edge of a thunderstorm.
The following is a summary of typical tornadoes:[2]
They may strike quickly, with little or no warning.
They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.
The average tornado moves Southwest to Northeast in the U.S., but tornadoes have been known to move in any direction.
The average forward speed of a tornado is 30 miles per hour (48 km/h), but has varied from stationary to 70 mph (110 km/h).
Tornadoes can also accompany tropical storms and hurricanes as they move onto land.
Waterspouts are tornadoes that form over water.
Tornadoes are most frequently reported east of the Rocky Mountains during spring and summer months.
Peak tornado season in the southern U.S. states is March through May; in the northern states, it is late spring through early summer.
Tornadoes are most likely to occur between 3 p.m. and 9 p.m. (local time), but have occurred at other times.[2]
Steps when expecting storms to arrive[edit]
The U.S. Federal Emergency Management Agency (FEMA) has advised the following precautions before a storm reaches an area:[4]
People were to be alert to the changing weather conditions.
They were to listen to NOAA Weather Radio or to local commercial radio or television newscasts for the latest information.
They were advised to watch various common danger signs, including:
dark, often greenish-colored sky;[4]
large hail stones;
a large, dark, low-lying cloud (particularly if rotating);
loud roar of wind, sounding similar to a freight train.
Upon seeing an approaching storm or noticing any of the danger signs, they were advised to prepare to take shelter immediately,[2] such as moving to a safe room, internal stairway, or other safe-haven area.
All individuals and families should have a disaster preparedness kit made prior to tornado. According to FEMA the kit should include items needed to shelter in place in the event of a disaster such as a tornado for up to 72 hours following impact.
The kit should include items such as:
water, a gallon per person per day
food, non-perishable and can opener
battery or hand crank radio
flashlight and batteries
whistle
dust mask for every individual
moist hand wipes and garbage bags
prescription medication and glasses
infant formula and diapers
pet food, extra water, collar and leash
first aid kit and first aid book
important documents such as identification, insurance policies and bank information
cash and coins
fire extinguisher
hygiene items and feminine supplies
blankets for each individual
change of clothing for each individual and sturdy shoes
paper and writing utensil
books, games and stuffed animals for children
[5]
Actions taken during tornadoes[edit]
During August 2010, FEMA advised people to perform the following actions when a tornado struck.[6]

Location
Action taken

In a structure (e.g. residence, small building, school, nursing home, hospital, factory, shopping center, high-rise building,restaurant)

They were to enter a pre-designated shelter area such as a safe room, basement, storm cellar, or the lowest building level.[6] If there was no basement, then to the center of an interior room on the lowest level (closet, interior hallway) away from corners, windows, doors, and outside walls. The goal has been to put as many walls as possible between there and the outside. They were advised to get under a sturdy table and use arms to protect head and neck, and not open windows.[6]

In a vehicle, trailer, or mobile home

They were advised to leave immediately and enter the lowest floor of a sturdy, nearby building or a storm shelter.[6] Mobile homes, even if tied down, offer little protection from tornadoes.[6] If a car is flipped by high winds, there is also the danger of broken glass.

On the outside with no shelter

They were advised to lie flat in a nearby ditch or depression and cover head with their hands.[6] Also, to beware of the potential for flooding there.
They were advised to not stay under an overpass or bridge (where winds or debris might be funneled). It was safer to be in a low, flat location.[6]
The advice was to never try to outrun a tornado in urban or congested areas in a car or truck, but instead, to leave the vehicle immediately for safe shelter.
Flying debris from tornadoes causes most fatalities and injuries.[6]

Because some preparations vary, depending on location, people have been advised to consult their local area preparedness plans, rather than assume the plans are similar for all areas, such as which local buildings have been designated as storm shelters.
A 2012 study of tornado injuries found that wearing a helmet such as those used for American football or bicycling, is an effective way to reduce injuries and deaths from head trauma.[7][8] As of 2012, the CDC endorsed only general head protection, but recommended that if helmets are to be used, they be kept close by to avoid wasting time searching for them.[9]
After the 2013 Moore tornado, it became apparent that thousands of people attempt to flee major tornadoes, and this has been credited with reducing the death toll. However, during this event some people were killed as the tornado passed over the traffic jam caused by the impromptu evacuation. In addition to urban traffic, evacuation can also be hampered by flash flooding produced by associated thunderstorms, and the need to be certain about the position and direction of the tornado. Others who did not flee the Moore tornado were also killed because the buildings they were hiding in were completely destroyed, highlighting the need for storm shelters and safe rooms constructed specifically to withstand very high winds.[10]
Long-term preparations[edit]
Depending on location, various safe-haven areas have been prepared. The goal has been to avoid outer walls which might collapse when a roof section becomes airborne and the walls below lose their upper support: many interior rooms resist collapse longer, due to smaller walls interconnected to each other, while outer walls deflect the force of the winds. Because mobile homes typically lack foundation anchors and present a large surface-area sail (to catch wind), the advice has been to seek a safe haven elsewhere, such as in a stronger nearby building.[6] When a mobile home begins to roll, people have been injured by hitting objects inside, or being crushed when a trailer suddenly hits the ground and begins to collapse around them.
In a multi-story building, an internal stairway (away from broken windows) often acts as a safe haven, due to the stairs reinforcing the walls and blocking any major debris falling from above. If a stairway is lined with windows, then there would be the danger of flying glass, so an interior stairway, or small inner room, would be preferable.
In private homes, some similar stairway rooms have been used, or an interior room/closet kept clear to quickly allow entry when a storm is seen or heard approaching (the wind roar intensifies, sounding like a swift "freight train" coming nearer, louder).[2] With weeks or months to prepare, an interior safe room can be constructed, with space for emergency water, food and flashlights, and a telephone to call for rescue if the exit becomes blocked by falling debris. Some above-ground safe rooms have been built with steel-rebar rods in cement-filled cinder blocks, to withstand winds of 250 miles per hour (400 km/h). Rural homes might have an outside storm cellar, or other external bunker, to avoid being trapped within a collapsing house. In rural homes, generators are also helpful to maintain power with enough fuel for a few days.
There were no building codes requiring tornado shelters nor specifically designed to prevent tornado damage[11] until the 2011 Joplin tornado prompted a local ordinance requiring hurricane ties or similar fasteners. The state of Oklahoma adopted the minimum U.S. standard that year for the first time, but did not add high-wind protections like those in Florida designed to protect against hurricanes.[12][13] Other states in Tornado Alley have no statewide building codes. The chance of any given location in Tornado Alley getting hit by an F-2 tornado (strong enough to do major structural damage and exceeding the 90 mph guideline for straightline winds) is about 1 every 4,000-5,000 years; in other areas the annual probability is one in several million.[11][14] The most stringent building codes only require earthquake strengthening for a 1 in every 500-1,000 year probability.[11]
The U.S. Federal Emergency Management Agency has spent tens millions of dollars subsidizing the construction of shelters and safe rooms in both private and public buildings.[12] Many buildings in Tornado Alley do not have basements, because unlike in more northern areas, there is no need for a deep foundation to get below the frost line, in some places the water table is high, and expansion and contraction of clay-heavy soils can produce additional pressure on buildings that can cause leaks if not reinforced.[15]
Medical preparations[edit]
Having a first aid kit in the safe haven is advised to help victims recover from minor injuries. People needing prescription medications could have a medicine bag ready to take to shelter. Some people have reported their "ears popping" due to the change in air pressure, but those effects seem to be temporary. Covering people with mattresses or cushions has helped avoid injury from flying debris,[6] as walls collapsed nearby.
Injuries sustained during a tornado vary in nature and in severity. The most common injuries experienced during a tornado are complex contaminated soft tissue wounds and account for more than 50% of the cases seen by emergency rooms following a tornado. These wounds will most likely be contaminated with soil and foreign bodies due to high wind speeds caused by tornadoes. Fractures are the second most common injury obtained after a tornado strikes and account for up to 30% of total injuries. Head injuries are also commonly reported during a tornado, but severe head injuries only account for less than 10% of the total. Even though only 10% of reported head injuries are severe, they are the most common cause of death following a tornado. Blunt trauma to the chest and abdomen are also injuries obtained following a tornado, but only account for less than 10% of overall injuries.[16]
Tornado drills[edit]



 Students participate in a tornado drill, lining up along an interior wall and covering their heads.
Tornado drills are an important element in tornado preparedness. Like any other safety drills, they increase chances of correct response to a real tornado threat.
Most states in the midwestern and southern United States conduct a statewide tornado drill in late winter or early spring in preparation for the severe weather season. During these drills, the National Weather Service issues test tornado warnings, and local Emergency Alert Systems and/or NOAA Weather Radio (normally as a Required Weekly Test or Required Monthly Test; Live Tornado Warning Codes can only be used if a waiver from the FCC is granted since "Live Code Testing" is prohibited per regulations) are activated along with outdoor warning sirens. Schools and businesses may also conduct a tornado drill simultaneously.
A tornado drill is a procedure of practicing to take cover in a specified location in the event that a tornado strikes an area. This safety drill is an important element of tornado preparedness.[17]
Generally, a signal is given, such as a series of tones (ex. Continuous Tone), or a voice announcement. Upon receiving the signal, building occupants of schools, hospitals, factories, shopping centers, etc. proceed to a designated location, usually an interior room or corridor with no windows, and assume a protective position.[18][19]
In homes and small buildings one must go to the basement or an interior room on the lowest floor (closet, bathroom), to stay away from glass.
Cars and mobile homes must be abandoned, if there is small chance to drive away.
In some jurisdictions, schools are required to conduct regular tornado drills, though generally less frequently than fire drills.
Tornado drills by state[edit]
[icon] This section requires expansion. (February 2013)
In many states tornado drills are part of the Severe Weather Awareness Week.
Alabama[20]
Florida[21]
Indiana
Iowa[22]
Ohio
Minnesota[23]
Missouri[24]
Texas
Virginia[25]
Wisconsin[26]
North Carolina http://www.wsoctv.com/news/weather/statewide-tornado-drill-part-severe-weather-awaren/nd5bC/
See also[edit]
Tornado myths#Safety
Derecho
Secondary flow
Tornadoes of 2014
Cultural significance of tornadoes
History of tropical cyclone-spawned tornadoes
List of tornadoes and tornado outbreaks
List of tornado-related deaths at schools
 Whirlwind (atmospheric phenomenon)
Microburst
Emergency management
Tropical cyclone warnings and watches
Tornado watch
Tornado warning


Portal icon Weather portal
References[edit]
1.Jump up ^ "Tornado Preparedness Tips for School Administrators", NOAA.gov, 2010, web: NOAA-sch.
2.^ Jump up to: a b c d e f g h i j k "Tornado", FEMA.gov, August 2010, web: FEMA-tornado.
3.Jump up ^ A speed of 300 miles per hour is 300*5280 = 1,584,000 feet per hour, or 440 feet (134 m) per second.
4.^ Jump up to: a b "What to do Before a Tornado", FEMA.gov, August 2010, web: FEMA-to.
5.Jump up ^ http://www.ready.gov/sites/default/files/documents/files/checklist_1.pdf
6.^ Jump up to: a b c d e f g h i j "What to Do During a Tornado", FEMA.gov, August 2010, web: FEMA-dur.
7.Jump up ^ http://www.uab.edu/icrc/tornado_helmet_com.html
8.Jump up ^ http://www.npr.org/2011/05/26/136645164/how-to-survive-a-tornado-plan-ahead-avoid-debris
9.Jump up ^ "Helmet and Tornado Statement". 2012-05-17. Retrieved 2013-08-18.
10.Jump up ^ Wade Goodwin (2013-06-01). NPR http://www.npr.org/2013/06/01/187876338/no-universal-best-practice-to-save-yourself-from-tornadoes. Retrieved 2013-08-18. Missing or empty |title= (help)
11.^ Jump up to: a b c http://www.livescience.com/13962-tornado-safety-building-codes.html
12.^ Jump up to: a b "Insight: In tornado alley, building practices boost damage". Reuters. 2013-06-08.
13.Jump up ^ http://stateimpact.npr.org/oklahoma/2013/07/03/moore-officials-delay-vote-on-strengthening-building-codes/
14.Jump up ^ http://web.archive.org/web/20060825011156/http://www.sciencenews.org/articles/20020511/bob9.asp
15.Jump up ^ http://www.npr.org/blogs/thetwo-way/2013/05/21/185857916/why-oklahomans-dont-like-basements
16.Jump up ^ Hogan, David (2007). Disaster Medicine. Philadelphia, PA: Lippincott Williams & Wilkins. p. 200.
17.Jump up ^ "Disaster Prep 101", ISBN 0942369033, pp154-155
18.Jump up ^ Florida Disaster[dead link]
19.Jump up ^ "Plano, Texas". Pisd.edu. Retrieved 2009-07-14.
20.Jump up ^ [1]
21.Jump up ^ [2]
22.Jump up ^ [3]
23.Jump up ^ Minnesota: Tornado Drill Day
24.Jump up ^ [4]
25.Jump up ^ Virginia: Tornado drill
26.Jump up ^ [5]
External links[edit]
Tornado Safety (Roger Edwards, Storm Prediction Center)
Tornado Storm Shelters
My Hazardous Statewide Guide
 


Categories: Tornado
Weather hazards
Disaster preparedness
Safety drills














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Tornado myths
From Wikipedia, the free encyclopedia
Jump to: navigation, search




 Windows and outer walls of the Bank One Building in downtown Fort Worth, Texas were damaged by the 2000 Fort Worth tornado. It is a commonly held belief that tornadoes cannot strike downtown areas, but Fort Worth is just one of many cities which have been struck by significant tornadoes.
Tornado myths are incorrect beliefs about tornadoes, some of which are no longer held. These beliefs can be attributed to many factors, including stories and news reports told by people unfamiliar with tornadoes, sensationalism by news media, and the presentation of incorrect information in popular entertainment. Common myths cover various aspects of the tornado, and include ideas about tornado safety, the minimization of tornado damage, and false assumptions about the size, shape, power, and path of the tornado itself.
It is thought by some people that taking shelter under highway overpasses or in the southwest corner of the building provides extra protection from a tornado, but both of these probably increase the danger of injury or death. Some still believe that opening windows ahead of a tornado will reduce the damage from the storm, but this is not true. Some people also believe that escaping in a vehicle is the safest method of avoiding a tornado, but this could increase the danger in some situations. Other myths are that tornadoes can skip houses, always travel in a predictable direction, always extend visibly from the ground to the cloud, and increase in intensity with increasing width. Finally, some people believe that tornadoes only occur in North America, do not occur in winter, are attracted to trailer park homes, or that some areas are protected from tornadoes by rivers, mountains, valleys, tall buildings or other geographical or man-made features; the truth is that tornadoes can occur almost anywhere at any time if the conditions are right. Some geographic areas are simply more prone to these conditions than others.


Contents  [hide]
1 Source
2 Safety 2.1 Safest location in a building
2.2 Opening windows to reduce tornado damage
2.3 Using highway overpasses as shelter
2.4 Escaping a tornado in a vehicle
3 Tornado behavior 3.1 Tornadoes "skipping" houses
3.2 Association of size with intensity
3.3 Appearing to reach the ground
3.4 Direction of travel
4 Geographical and temporal influences 4.1 Geographical scope
4.2 Near rivers, valleys, mountains, or other terrain features
4.3 Attraction to mobile homes and/or trailer parks
4.4 Downtown areas
4.5 During winter
5 See also
6 References
7 External links

Source[edit]
Tornadoes are subject to a great deal of speculation and misinformation. Some tornado myths are remaining bits of folklore which are still passed down by word of mouth. The idea that the southwest corner of a structure is the safest place in a tornado was first published in the 1800s, and is still quoted today despite being thoroughly debunked in the 1960s and 70s.[1] Many tornado myths are actively spread by media outlets. News reporters unfamiliar with the science behind tornadoes tend to repeat "common wisdom" which has since been proven incorrect. One notable instance of mass media spreading a tornado myth was after the 1999 Oklahoma tornado outbreak, where TIME magazine ran a caption on a picture suggesting that highway overpasses were safer tornado shelters than houses.[2][3] The spread of some myths can even be attributed to sensationalism in the media or in popular tornado-themed movies such as The Wizard of Oz and Twister.[4]
Safety[edit]
Main article: Tornado preparedness
Safest location in a building[edit]



 The central room on the lowest floor of a house is by far the safest area during a tornado. In multilevel apartment buildings, this will mean the ground floor units. Often the upper levels are built with lighter, weaker materials. This house near Jasper, Texas was destroyed by an F2 tornado, with only a few interior walls still standing.[5]
In 1887, the first book on tornadoes was written by John Park Finley, a pioneer in the field of tornado research. While it was a revolutionary book containing many breakthrough ideas, it contained a few ideas which have since been proven false.[1] One of these was the idea that the northeast or east part of a structure was the least safe, and should be avoided when seeking shelter from a tornado. This advice was unrefuted and heeded by many until the 1960s.[1]
This myth was derived from two misconceptions: First, that tornadoes always travel in a northeasterly direction, and second, that debris from a structure will be carried away in the direction of the tornado's propagation, leaving anyone taking shelter on the side of the structure facing the tornado's approach unharmed.[1][6] The seriousness of these misconceptions began to be revealed in the 1960s and 1970s, when surveys of major tornado damage in residential areas showed that the section of a house in the direction of the tornado's approach is actually the least safe.[1] Additionally, many tornadoes have traveled in directions other than northeasterly, including the Jarrell Tornado (F5 on the Fujita scale), which moved south-southwesterly.[1][7] Because determining a tornado's direction of approach can take time away from seeking shelter, official advice is to seek shelter in an interior room on the lowest floor of a building, under a staircase, I-beam, or sturdy piece of furniture if possible.[6]
Opening windows to reduce tornado damage[edit]
One of the oldest pieces of tornado folklore is the idea that tornadoes do most of their damage due to the lower atmospheric pressure at the center of a tornado, which causes the house to explode outward. As the theory goes, opening windows helps to equalize the pressure.[8]
The source of this myth is from the appearance of some destroyed structures after violent tornadoes. When one wall receives the extreme pressure of tornado winds, it will likely collapse inward. This then leads to a considerable outward pressure on the three remaining walls, which fall outwards as the roof falls down, creating the impression of a house which has exploded. Indeed, damage surveys of "exploded" houses usually show at least one wall which has blown inward.[8] Additionally, if the roof is lifted before any walls fail, the walls can fall in any direction. If they fall outward, this structure can also appear to have exploded.[9]
In even the most violent tornadoes, there is only a pressure drop of about 10%, which is about 1.4 pounds per square inch (9.7 kPa).[10] Not only can this difference be equalized in most structures in approximately three seconds, but if a significant pressure differential manages to form, the windows will break first, equalizing the pressure.[1] Additionally, as the windows are the most fragile parts of a house, in a significant tornado flying debris will likely break enough windows to equalize any pressure difference fairly quickly. Regardless of any pressure drop, the direct effects of a tornado's winds are enough to cause damage to a house in all but the weakest tornadoes.[1][6]
Current advice is that opening windows in advance of a tornado wastes time that could be spent seeking shelter. Also, being near windows is very dangerous during a severe weather event, possibly exposing people to flying glass.[11]
Using highway overpasses as shelter[edit]



 The El Dorado Lake tornado overpass, above, had an unusual construction which provided a sheltered area for the camera crew. Most overpasses, like the Shields Boulevard Overpass at bottom, provide little or no shelter to tornado winds and flying debris.[7]
The first documented instance of a person using a highway overpass for shelter from a tornado occurred in Wichita Falls, Texas on April 10, 1979. A man stuck in a traffic jam as the tornado approached left his vehicle and lay flat on an embankment beneath an overpass, surviving a violent tornado with only minor injuries.[7] In 1991, a highly publicized event occurred in which a television crew and several others survived the passage of a tornado near El Dorado, Kansas by huddling underneath an overpass, bracing themselves against steel girders. The sensational footage taken by the television crew was broadcast across the United States. This and other media coverage helped to fuel the myth that the underside of bridges or overpasses are good shelters when a tornado strikes.[7]
However, in the El Dorado tornado, several unique factors came together to protect the film crew and others seeking shelter under the bridge.[7] The tornado did not pass directly over the filmed bridge, but instead tracked slightly south of the area, exposing the people to winds less damaging than those in the tornado core. The overpass had an unusual design which included a hollow crawlspace at the top of the embankment, which was large enough to allow people to crawl inside and hold the exposed girders against the wind. This design also allowed for added protection against high-speed debris.[7]
These cases led to a false belief among many that highway overpasses were good shelter from a tornado.[7] The belief was so strong among some that, in at least one case during the 1999 Oklahoma tornado outbreak, an individual left her well-built home and drove several miles to seek shelter under an overpass, in the mistaken belief that she was safer there than inside her house.[7] During the outbreak, a violent tornado directly struck three highway overpasses, and at each one there was a fatality. All of the individuals received significant injuries from tornadic debris, and several were swept into the tornado itself.[7] By contrast, the same tornado struck approximately 2,000 homes in Moore, Oklahoma, completely destroying many, yet resulting in only 3 fatalities.[7]
From scientific lessons learned, especially in the wake of the 1999 Oklahoma outbreak, meteorologists insist that overpasses are insufficient shelter from tornado winds and debris, and may be the worst place to be during a violent tornado.[7] The embankment under an overpass is higher than the surrounding terrain, and the wind speed increases with height. Additionally, the overpass design may create a "wind-tunnel" effect under the span, further increasing the wind speed. Many overpasses are completely exposed underneath and most lack hanging girders or a crawlspace-like area to provide sufficient protection from debris, which can travel at high speeds even in weak tornadoes. People stopping underneath overpasses block the flow of traffic, putting others in danger.[7][12]
Escaping a tornado in a vehicle[edit]



 A 2008 tornado lifted this school bus and flipped it on top of a damaged elementary school in Caledonia, Mississippi.
Often people try to avoid or outrun a tornado in a vehicle. In theory, cars can travel faster than the average tornado, and so it is better to avoid the tornado altogether than take shelter in its path.[13] The official directive from the National Weather Service is for house-dwellers in the path of a tornado to take shelter at home rather than risk an escape by vehicle.[14] This is a result of several factors and statistics. An interior room inside a well-built frame house (especially one with a basement) provides a reasonable degree of protection from all but the most violent tornadoes. Underground or above-ground tornado shelters, as well as extremely strong structures such as bank vaults, offer almost complete protection. Cars, on the other hand, can be heavily damaged by even weak tornadoes, and in violent tornadoes they can be thrown large distances, even into buildings. High-profile vehicles such as buses and tractor trailers are even more vulnerable to high winds.[15][16]
There are many reasons to avoid cars when a tornado is imminent. Severe thunderstorms which produce tornadoes can produce flooding rains, hail, and strong winds far from the tornado-producing area, all of which can make driving difficult or even impossible. Some tornadoes move faster than some cars (record speed for a tornado moving across land is 116.8 km/h[citation needed]), even when the road is clear and flat. Any of these situations can leave drivers stranded in the path of the tornado far from substantial shelter.[16] When coupled with driver panic, they may also result in dangerous but preventable accidents.[16] This situation would be magnified greatly if all the residents of a warned area left in their vehicles, which would cause traffic jams and accidents as the tornado approached.[16] Numerous victims of the deadly Wichita Falls, Texas tornado on April 10, 1979 died in their vehicles in such a situation.[15]
If a person spots a nearby tornado while driving, the official National Weather Service directive has been for the individual to abandon the car and seek shelter in a ditch or culvert, or substantial shelter if nearby.[14] Far-away, highly visible tornadoes, however, can be successfully fled from at right angles (90-degrees) from its direction of apparent movement.[11] Despite dangers inherent with operating a vehicle during a tornado, given sufficient advanced warning, mobile home residents have been instructed by the National Weather Service to drive to the nearest secure shelter during a warning.[17]
Tornado behavior[edit]
Tornadoes "skipping" houses[edit]
Several different phenomena have lent credence to the idea that tornadoes "skip".[11] Tornadoes vary in intensity along their path, sometimes drastically over a short period and distance. If a tornado was causing damage, then weakened to the point where it could cause no damage, followed by a re-intensification, it would appear as if it "skipped" a section. Occasionally with violent tornadoes, a smaller subvortex within a tornado will completely destroy a structure next to another building which appears almost unscathed and thus apparently "skipped".[11][18]
It is true that a house that is between two destroyed homes can be "untouched", but this is not the result of a tornado "skipping" as was previously thought. After the 1974 tornado Super Outbreak, Dr. Ted Fujita studied many films of tornadoes from that day. Included in his review was damage and tornado film footage of F4 and F5 tornadoes. Fujita concluded that multiple vortices, highly volatile tornadic satellites transiting within a parent tornado at high speeds, are responsible for making tornadoes appear to "skip houses".[19] The phenomenon of satellite tornadoes where a smaller tornado orbits a larger companion tornado can also lead to gaps in damage between the two tornadoes.
Weaker tornadoes, and at times even stronger tornadoes, can occasionally "lift", meaning their circulation has ceased to affect the ground. The result is an erratic and discontinuous linear damage path, leading to the term skipping tornado. These discontinuities tend to occur over areas larger than the small neighborhoods where the "house-skipping" effect is observed, except possibly at the time of the birth and organization of the tornado.[20] There is not commonly observed and now a rarely applied term. Typically, when one tornado weakens and another forms this is a process of successive parent mesocyclones forming and decaying in a process known as cyclic tornadogenesis leading to a series of tornadoes spawned by the same supercell which are known as a tornado family.
Association of size with intensity[edit]



 The Elie, Manitoba Tornado of June 22, 2007 appeared small and narrow throughout its lifespan, yet was the first tornado in Canadian history to cause F5 damage.
Some people have been led to assume that small, skinny tornadoes are always weaker than large, wedge-shaped tornadoes.[6] There is an observed trend of wider tornadoes causing worse damage. It is unknown whether this is due to an actual tendency of tornado dynamics or an ability for the tornado to affect a larger area.[11] However, this is not a reliable indicator of an individual tornado's intensity. Some small, rope-like tornadoes, traditionally thought of as weak, have been among the strongest in history.[11] Since 1950, more than 100 violent tornadoes (F4/EF4 or higher) had a maximum width of 300 feet (91 m).[21] Also, tornadoes typically change shape during the course of their lifespan, further complicating any attempt to classify how dangerous a tornado is as it is occurring.[22]
Appearing to reach the ground[edit]
It is commonly and mistakenly thought that if the condensation funnel of a tornado does not reach the ground, then the tornado cannot cause substantial damage. This is another deadly myth. A tornado appears to be on the ground only when its condensation funnel descends to the surface, but this is misleading. The circular, violent surface winds, not the condensation funnel, are what both define the tornado and cause the tornado's damage. Spotters should keep sight of swirling debris directly under any visible funnel or rotating wall cloud, even if such structures appear to not descend entirely to the ground.[22][23] Additionally, tornadoes can be wrapped in rain and thus may not be visible at all.[23]
Direction of travel[edit]
It has been thought in the past that tornadoes moved almost exclusively in a northeasterly direction.[6] This is false, and a potentially deadly myth which can lead to a false sense of security, especially for unaware spotters or chasers. Although the majority of tornadoes move northeast, this is normally due to the motion of the storm, and tornadoes can arrive from any direction. The expectation of northeasterly travel may be accurate in many cases, but is no more than a statistical observation about tornadoes in general that any particular tornado may defy at any time. A deadly F5 tornado that hit the city of Jarrell, Texas in 1997 moved to the southwest - directly opposite of commonly expected storm motion. Additionally, tornadoes can shift without notice due to storm motion changes or effects on the tornado itself from factors such as its rear flank downdraft.[11]
Geographical and temporal influences[edit]
Geographical scope[edit]



 Areas worldwide where tornadoes are most likely, indicated by orange shading
It is often thought that tornadoes only occur in North America.[24] The majority of tornadoes do occur in the United States; however, tornadoes have been observed on every continent except Antarctica.[25]
Besides North America, Australia, the United Kingdom, western Russia, Bangladesh and the Philippines also experience tornadoes on a regular basis.[26]
See also: Tornado climatology § Geography
Near rivers, valleys, mountains, or other terrain features[edit]
There are many misconceptions involving the effect of terrain features—bodies of water, mountains, valleys, and others—on tornado formation and behavior. Most of these beliefs stem from the idea that tornadoes cannot cross or form near these terrain features. While most modes of tornadogenesis are poorly understood,[22][27] no terrain feature can prevent the occurrence of a tornado.[6]
Small bodies of water such as lakes and rivers are insignificant obstacles to tornadoes. Violent tornadoes have formed over rivers and lakes—including the 1878 Wallingford tornado and the 1899 New Richmond tornado—as well as crossing over them after forming elsewhere. More than a dozen tornadoes have crossed the Mississippi River in recorded history.[28] Regarding mountains, tornadoes have been observed on terrain as high as 12,000 feet (3,700 m) above sea level, and have been known to pass up a 3,000-foot (910 m) ridge unaffected.[1][29]
These myths have been debunked in the past. The devastating Tri-State Tornado crossed two major rivers along a record 219-mile (352 km) or longer path.[20] In 1944, a violent tornado cut a continuous path at least 60 miles (97 km) through heavily forested and mountainous territory in West Virginia, killing at least 100 people.[30] A hill known as Burnett's Mound on the southwest end of Topeka, Kansas was purported to protect the city from tornadoes, according to an old legend. However, in 1966, an F5 tornado passed directly over the hill through downtown, killing 18 people and causing $100 million (1966 USD) in damage.[31] Downtown Memphis, Tennessee was believed by residents to be protected from tornadoes and other severe weather by the Chickasaw Bluff along the Mississippi River. Though not a tornado, the devastating derecho during the Memphis Summer Storm of 2003 debunked this myth, killing seven and causing $1 billion in damage. During the Super Outbreak, violent tornadoes crossed dozens of rivers, including the Ohio, Detroit River as well as crossing over mountains and ridges hundreds of feet high.[32] Another example of tornadoes hitting mountainous regions of the United States is the April 25–28, 2011 tornado outbreak, which hit mountainous parts of East Tennessee, Northeast Alabama, Southwest Virginia and North Georgia, killing many people, including an entire family of 4 in Ringgold, Georgia.[33]
Attraction to mobile homes and/or trailer parks[edit]



 This mobile home was destroyed by a relatively weak EF0 tornado.
The idea that manufactured housing units, or mobile homes, attract tornadoes has been around for decades. This may appear to be true at first from looking at tornado fatality statistics: from 2000 to 2008, 539 people were killed by tornadoes in the US, with more than half (282) of those deaths in mobile homes.[34] Only around 6.8% of homes in the US are "manufactured/mobile homes".[35]
However, it is highly unlikely that single-story structures such as mobile homes can have a substantial effect on tornado development or evolution. More people are killed in trailer parks because mobile homes are less able to withstand high winds than permanent structures. Winds which can demolish or roll a mobile home may only cause roof damage to a typical one- or two-family permanent residence.[36] Another likely contributing factor to the continued propagation of this myth is confirmation bias: whenever a new instance of a tornado hitting a mobile home park occurs, media outlets report on it more extensively, ignoring damage to the surrounding area which may not have produced as many casualties.[37]
Downtown areas[edit]
See also: List of tornadoes striking downtown areas of large cities



 Tornadoes are extremely rare in Utah, but downtown Salt Lake City was struck by this F2 tornado in 1999, which killed one person.
Some people believe that, for various reasons, large cities cannot be struck by tornadoes. More than 100 tornadoes have struck downtown areas of large cities in recorded history. Many cities have been struck twice or more, and a few—including Lubbock, Texas; St. Louis, Missouri; Topeka, Kansas; and London, England—have been struck by violent tornadoes (F4 or stronger).[21][38]
Tornadoes may seem rare in downtown areas because downtown areas cover such a small geographical area. Considering the size of a central business district is very small compared to the city limits, tornadoes will strike outside of the downtown area more often.[1]
The misconception, like most, has a small basis in truth. Research has been done in a few metropolitan areas suggesting that the urban heat island effect may discourage the formation of weak tornadoes in city centers, due to turbulent warm air disrupting their formation. This does not apply to significant tornadoes, however, and it is possible that the presence of tall buildings may actually intensify storms which move into downtown areas.[1]
During winter[edit]
See also: Tornado climatology and List of tornadoes by calendar day
Because they generally require warm weather to form, tornadoes are uncommon in winter in the mid-latitudes.[39] However, they can form, and tornadoes have even been known to travel over snow-covered surfaces.[40] Deadly tornadoes are no exception: from 2000 to 2008, 135 of the 539 US tornado deaths occurred during meteorological winter (December through February).[34] Tornadoes in winter may be more dangerous, since they tend to move faster than tornadoes at other times of the year.[41]
See also[edit]
List of common misconceptions
List of F5 and EF5 tornadoes
List of tornadoes and tornado outbreaks
List of tornadoes striking downtown areas
Tornado records
Shape of tornadoes
Size of tornadoes
Tornadoes of 2014
References[edit]
1.^ Jump up to: a b c d e f g h i j k "Myths and Misconceptions about Tornadoes". Tornado Project. 1999. Retrieved 2013-05-31.
2.Jump up ^ Miller, Daniel J.; Doswell, Charles A., III; Brooks, Harold E.; Stumpf, Gregory J.; Rasmussen, Erik (1999). "Highway Overpasses as Tornado Shelters". National Weather Service WFO Norman, Oklahoma. p. 2. Retrieved June 29, 2009.
3.Jump up ^ Carter, J. Pat (1999-05-04). "The Force of Nature". TIME magazine. Retrieved June 30, 2009.
4.Jump up ^ Grazulis, Thomas P (2001). The Tornado: Nature's Ultimate Windstorm (Google Books). University of Oklahoma Press. p. 7. ISBN 0806132582. Retrieved 2009-02-15.
5.Jump up ^ "Tornadoes & Severe Weather November 17th & 18th, 2003". National Weather Service, Lake Charles, Louisiana. 2008-03-06. Retrieved 2008-06-24.
6.^ Jump up to: a b c d e f MKX Webmaster (April 10, 2009). "Severe Weather Awareness - Common Tornado Myths". Milwaukee, Wisconsin/Sullivan, WI: National Weather Service. Retrieved June 29, 2009.
7.^ Jump up to: a b c d e f g h i j k l Miller, Daniel J.; Doswell, Charles A., III; Brooks, Harold E.; Stumpf, Gregory J.; Rasmussen, Erik (1999). "Highway Overpasses as Tornado Shelters". National Weather Service WFO Norman, Oklahoma. Retrieved June 29, 2009.
8.^ Jump up to: a b "Tornado Information for Schools" (PDF). Butler County, Ohio Emergency Management Agency. Retrieved June 29, 2009. Cited link is not found. "Wayback article" (PDF). Retrieved May 9, 2007.
9.Jump up ^ Ryan, Bob (December 15, 2005). "Answers archive: Tornado safety". USA Today. Retrieved June 29, 2009.
10.Jump up ^ Lee, Julian J.; T.P. Samaras, C.R. Young (October 2004). "Pressure Measurements at the ground in an F-4 tornado". Preprints of the 22nd Conference on Severe Local Storms. Hyannis, Massachusetts: American Meteorological Society.
11.^ Jump up to: a b c d e f g Edwards, Roger (January 29, 2009). "The Online Tornado FAQ". Storm Prediction Center. Retrieved June 29, 2009.
12.Jump up ^ "Severe Weather Safety Guide" (PDF). National Weather Service Paducah, Kentucky. 2007-12-12. Retrieved June 29, 2009.
13.Jump up ^ "Tornado and Lightning Myths". Environment Canada. 2004-10-27. Retrieved 2009-06-11.
14.^ Jump up to: a b DeWald, Van L. (February 26, 1999). "Tornado Safety in Your Vehicle". National Weather Service Storm Spotting and Weather Safety. National Weather Service Louisville, Kentucky. p. 71. Retrieved June 29, 2009.
15.^ Jump up to: a b Burgess, Don (2006-06-13). "The April 10, 1979 Severe Weather Outbreak". National Weather Service Norman, Oklahoma. Retrieved 2008-06-22.
16.^ Jump up to: a b c d "Tornado Safety in Cars". The Tornado Project. 1999. Retrieved 2009-06-11.
17.Jump up ^ DeWald, Van L. (February 26, 1999). "Tornado Safety in Your Mobile Home". National Weather Service, Louisville, Kentucky. Retrieved 2009-06-11.
18.Jump up ^ "What are some common tornado myths?". National Weather Service, Norman, Oklahoma. 2008-10-20. Retrieved 2009-06-11.
19.Jump up ^ McCarthy, Daniel; Schaefer, Joseph (2003-11-10). "Tornado Trends Over the Past Thirty Years". Storm Prediction Center. Retrieved 2009-06-11.
20.^ Jump up to: a b "Frequently Asked Questions (FAQ)". National Weather Service Norman, Oklahoma. October 20, 2008. Archived from the original on April 7, 2008. Retrieved June 29, 2009.
21.^ Jump up to: a b Data from the Storm Prediction Center archives, which are accessible through SeverePlot, free software created and maintained by John Hart, lead forecaster for the SPC.
22.^ Jump up to: a b c Doswell, Moller, Anderson et al. (2005). "Advanced Spotters' Field Guide" (PDF). United States Department of Commerce. Retrieved 2006-09-20.
23.^ Jump up to: a b "What you need to know about TORNADOES". Wisconsin Emergency Management Office. Retrieved 2009-06-11.
24.Jump up ^ Williams, Jack (2004-05-28). "Answers: Do tornadoes occur outside the USA". USA Today. Retrieved 2009-06-11.
25.Jump up ^ Perkins, Sid (2002-05-11). "Tornado Alley, USA". Science News. pp. 296–298. Archived from the original on August 25, 2006. Retrieved 2006-09-20.
26.Jump up ^ "U.S. Tornado Climatology". National Climatic Data Center. 2008-04-10. Retrieved 2009-06-11.
27.Jump up ^ Biggerstaff, Michael I.; Wicker, Louis J.; Guynes, Jerry; Ziegler, Conrad; Straka, Jerry M.; Rasmussen, Erik N.; Doggett, Arthur IV; Carey, Larry D.; Schroeder, John L.; Weiss, Chris (September 2005). "The Shared Mobile Atmospheric Research and Teaching Radar" (PDF). Bulletin of the American Meteorological Society (American Meteorological Society) 86 (9): 1263–1274. Bibcode:2005BAMS...86.1263B. doi:10.1175/BAMS-86-9-1263. Retrieved June 29, 2009.
28.Jump up ^ Grazulis, Thomas P. (2001). "Tornado Myths". The Tornado: Nature's Ultimate Windstorm (Google Books). University of Oklahoma Press. p. 148. ISBN 0806132582. Retrieved 2009-02-15.
29.Jump up ^ Monteverdi, John; Edwards, Roger; Stumpf, Greg; and Gudgel, Daniel (September 13, 2006). "Tornado, Rockwell Pass Sequoia National Park, July 7, 2004". Retrieved June 29, 2009.
30.Jump up ^ Grazulis, Thomas P (July 1993). Significant Tornadoes 1680–1991. St. Johnsbury, VT: The Tornado Project of Environmental Films. p. 915. ISBN 1-879362-03-1.
31.Jump up ^ Grazulis, Thomas P (2001). "Tornado Myths". The Tornado: Nature's Ultimate Windstorm (Google Books). University of Oklahoma Press. pp. 146–147. ISBN 0806132582. Retrieved 2009-02-15.
32.Jump up ^ Grazulis, Thomas P (July 1993). Significant Tornadoes 1680–1991. St. Johnsbury, VT: The Tornado Project of Environmental Films. pp. 1153–1163. ISBN 1-879362-03-1.
33.Jump up ^ Ringgold residents return to 'utter devastation' from tornadoes, WXIA-TV, April 29, 2011. Retrieved April 30, 2011.
34.^ Jump up to: a b "Annual U.S. Killer Tornado Statistics". Storm Prediction Center. June 17, 2009. Retrieved June 29, 2009.
35.Jump up ^ "Table 1A-2. Height and Condition of Building—All Housing Units" (PDF). United States Census Bureau. 2007. Retrieved June 29, 2009.
36.Jump up ^ "A Recommendation for an Enhanced Fujita Scale (EF-Scale)" (PDF). Wind Science and Engineering Center, Texas Tech University. 2006-10-10. Retrieved June 29, 2009.[dead link]
37.Jump up ^ Grazulis, Thomas P (2001). "Tornado Myths". The Tornado: Nature's Ultimate Windstorm (Google Books). University of Oklahoma Press. p. 152. ISBN 0806132582. Retrieved 2009-02-15.
38.Jump up ^ "British & European Tornado Extremes". TORRO. 2009. Retrieved June 29, 2009.
39.Jump up ^ Zabarenko, Deborah (February 7, 2008). "Deadly winter tornadoes not rare: NOAA". Reuters. Retrieved June 29, 2009.
40.Jump up ^ Lyons, Walter A (1997). "Tornadoes". The Handy Weather Answer Book (2nd ed.). Detroit, Michigan: Visible Ink press. pp. gs. 175–200. ISBN 0-7876-1034-8.
41.Jump up ^ Britt, Robert Roy (2009-02-11). "Tornadoes in Winter?". LiveScience. Retrieved July 1, 2009.
Klockow, Kimberly E.; R. A. Peppler; R. A. McPherson (2014). "Tornado Folk Science in Alabama and Mississippi in the 27 April 2011 Tornado Outbreak". GeoJournal. doi:10.1007/s10708-013-9518-6.
External links[edit]
Tornado Myths and Facts National Climatic Data Center
Tornado Myths (Tornado Pictures Website)
Tornado Myths and Tornado Reality
LaPorte, Texas Emergency Management (PDF)
Video comparing houses with open and closed doors in high winds - though construction is also different
This is a good article. Click here for more information.
 


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Tornado records
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 A map of the tornado paths in the Super Outbreak
This article lists various tornado records. The most extreme tornado in recorded history was the Tri-State Tornado, which roared through parts of Missouri, Illinois, and Indiana on March 18, 1925. It was likely an F5, though tornadoes were not ranked on any scale in that era. It holds records for longest path length at 219 mi (352 km), longest duration at about 3.5 hours, and fastest forward speed for a significant tornado at 73 mph (117 km/h) anywhere on Earth. In addition, it is the deadliest single tornado in United States history (695 dead).[1] It was also the second costliest tornado in history at the time, but has been surpassed by several others non-normalized. When costs are normalized for wealth and inflation, it still ranks third today.[2]
The deadliest tornado in world history was the Daulatpur–Saturia tornado in Bangladesh on April 26, 1989, which killed approximately 1,300 people.[3] Bangladesh has had at least 19 tornadoes in its history kill more than 100 people, almost half of the total for the rest of the world.
For 37 years, the most extensive tornado outbreak on record, in almost every category, was the Super Outbreak, which affected a large area of the central United States and extreme southern Ontario in Canada on April 3 and April 4, 1974. Not only did this outbreak feature an incredible 148 tornadoes in only 18 hours, but an unprecedented number of them were violent; 7 were of F5 intensity and 23 were F4. This outbreak had a staggering 16 tornadoes on the ground at the same time at the peak of the outbreak. More than 300 people, possibly as many as 330, were killed by tornadoes during this outbreak. However, this record was later broken during the April 25–28, 2011 tornado outbreak, which resulted in 355 tornadoes and 324 tornadic fatalities.[4]


Contents  [hide]
1 Tornado outbreaks 1.1 Most tornadoes in single 24-hour period
1.2 Longest continuous outbreak and largest autumnal outbreak
1.3 Greatest number of tornadoes spawned from a hurricane
2 Tornado casualties and damage 2.1 Deadliest single tornado in world history
2.2 Deadliest single tornado in US history
2.3 Most damaging tornado
3 Largest and most powerful tornadoes 3.1 Highest winds observed in a tornado
3.2 Longest damage path and duration
3.3 Longest path and duration tornado family
3.4 Largest path width
3.5 Highest forward speed
3.6 Greatest pressure drop
4 Early tornadoes 4.1 Earliest known tornado in Europe
4.2 Earliest known tornado in the Americas
4.3 First confirmed tornado and first tornado fatality in present-day United States
5 Exceptional tornado droughts 5.1 Longest span without a tornado rated F5 or EF5
6 Exceptional survivors 6.1 Longest distance carried by a tornado
7 Exceptional coincidences 7.1 Codell, Kansas
7.2 Tanner/Harvest, Alabama
7.3 Moore, Oklahoma
7.4 Tuscaloosa, Alabama
7.5 Birmingham, Alabama
7.6 St. Louis, Missouri
7.7 McConnell AFB/Haysville, Kansas
8 See also
9 References
10 External links

Tornado outbreaks[edit]
Most tornadoes in single 24-hour period[edit]
The April 25–28, 2011 tornado outbreak was the most prolific tornado outbreak in U.S. history. It produced 355 tornadoes, with 211 of those in a single 24-hour period on April 27,[5] including 11 EF4 and 4 EF5 tornadoes. 348 deaths occurred in that outbreak, of which 324 were tornado related. The outbreak helped smash the record for most tornadoes in the month of April with 765 tornadoes, almost triple the prior record (267 in April 1974). The overall record for a single month was 542 in May 2003, which was also broken.[6]
The infamous Super Outbreak of April 3–4, 1974, which spawned 148 confirmed tornadoes across eastern North America, held the record for the most prolific tornado outbreak for many years. Not only did it produce an exceptional number of tornadoes, but it was also an inordinately intense outbreak producing dozens of large, long-track tornadoes, including 7 F5 and 23 F4 tornadoes. More significant tornadoes occurred within 24 hours than any other week in the tornado record.[7] Due to a secular trend in tornado reporting, the 2011 and 1974 tornado counts are not directly comparable.
Longest continuous outbreak and largest autumnal outbreak[edit]
Most tornado outbreaks in North America occur in the spring, but there is a secondary peak of tornado activity in the fall which is less consistent but can include exceptionally large and/or intense outbreaks. In 1992, an estimated 95 tornadoes broke out in a record 41 hours of continuous tornado activity from November 21 to 23. This is also among the largest known outbreaks in areal expanse. Many other very large outbreaks have occurred in autumn, especially in October and November.[1]
Greatest number of tornadoes spawned from a hurricane[edit]
The greatest number of tornadoes spawned from a hurricane is 118 from Hurricane Ivan in 2004.[8] Caution is advised comparing the raw number of counted tornadoes from recent decades to decades prior to the 1990s since more tornadoes that occur are now recorded than in the past.
Tornado casualties and damage[edit]
For a more comprehensive list, see List of tornadoes causing 100 or more deaths.

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Deadliest single tornado in world history[edit]
On April 26, 1989 in Bangladesh a massive tornado took at least 1,300 lives.[9]
Deadliest single tornado in US history[edit]
The Tri-State Tornado of March 18, 1925 killed 695 people in Missouri (11), Illinois (613), and Indiana (71). The outbreak it occurred with was also the deadliest known tornado outbreak, with a combined death toll of 747 across the Mississippi River Valley.[1]
Most damaging tornado[edit]
Similar to fatalities, damage (and observations) of a tornado are a coincidence of what character of tornado interacts with certain characteristics of built up areas. That is, destructive tornadoes are in a sense "accidents" of a large tornado striking a large population. In addition to population and changes thereof, comparing damage historically is subject to changes in wealth and inflation. The 1896 St. Louis–East St. Louis tornado on May 27, incurred the most damages adjusted for wealth and inflation, at an estimated $2.9 billion (1997 USD). In raw numbers, the Joplin tornado of May 22, 2011 is considered the costliest tornado in recent history, with damage totals near $2.8 billion (2011 USD). Until 2011, the "Oklahoma City tornado" of May 3, 1999 was the most damaging.[10]
Largest and most powerful tornadoes[edit]
Highest winds observed in a tornado[edit]
During the F5 1999 Bridge Creek–Moore tornado on May 3, 1999, a Doppler on Wheels situated near the tornado measured winds of 301 ± 20 mph (484 ± 32 km/h) momentarily in a small area inside the funnel approximately 100 m (330 ft) above ground level.[11]
On May 31, 2013, a tornado hit rural area south of El Reno, Oklahoma. The tornado was originally rated as an EF3 based on damage; however, after mobile radar data analysis was conducted, it was concluded to have an EF5 due to a measured wind speed which topped at 296 mph (476 kmh), second only to the Bridge Creek - Moore tornado. Despite the recorded windspeed, the El Reno tornado was later downgraded back to EF3 due to the fact that no EF5 damage was found.[12][13]
Winds were measured at 257–268 mph (414–431 km/h) using portable Doppler radar in the Red Rock, Oklahoma tornado during the April 26, 1991 tornado outbreak. Though these winds are possibly indicative of an F5 strength tornado, this particular tornado's path never encountered any significant structures and caused minimal damage. Thus it was rated an F4.[14]
Longest damage path and duration[edit]
The longest known track for a single tornado is the Tri-State Tornado with a path length of 151 to 235 mi (243 to 378 km). For years there was debate whether the originally recognized path length of 219 mi (352 km) over 3.5 hours was from one tornado or a series. Some very long track (VLT) tornadoes were later determined to be successive tornadoes spawned by the same supercell thunderstorm, which are known as a tornado family. The Tri-State Tornado, however, appeared to have to no gaps in the damage. A six year reanalysis study by a team of severe convective storm meteorologists found insufficient evidence to make firm conclusions but does conclude that it is likely that the beginning and ending of the path was resultant of separate tornadoes comprising a tornado family. It also found that the tornado began 15 mi (24 km) to the west and ended 1 mi (1.6 km) farther east than previously known, bringing the total path to 235 mi (378 km). The 174 mi (280 km) segment from central Madison County, Missouri to Pike County, Indiana is likely one continuous tornado and the 151 mi (243 km) segment from central Bollinger County, Missouri to western Pike County, Indiana is very likely a single continuous tornado. Another significant tornado was found about 65 mi (105 km) east-northeast of the end of aforementioned segment(s) of the Tri-State Tornado Family and is likely another member of the family. Its path length of 20 mi (32 km) over about 20 min makes the known tornado family path length total to 320 mi (510 km) over about 5.5 hours[15] Grazulis in 2001 wrote that the first 60 mi (97 km) of the (originally recognized) track is probably the result of two or more tornadoes and that a path length of 157 mi (253 km) was seemingly continuous.[16]
Longest path and duration tornado family[edit]
What at one time was thought to be the record holder for the longest tornado path is now thought to be the longest tornado family, with a track of at least 293 miles (472 km) on May 26, 1917 from the Missouri border across Illinois into Indiana. It caused severe damage and mass casualties in Charleston and Mattoon, Illinois.[1]
What was probably the longest track supercell thunderstorm tracked 790 miles (1,270 km) across 6 states in 17.5 hours on March 12, 2006 as part of the March 2006 tornado outbreak sequence. It began in Noble County, Oklahoma and ended in Jackson County, Michigan, producing many tornadoes in Missouri and Illinois.[17]
Largest path width[edit]
The widest tornado on record may be the El Reno, Oklahoma tornado of May 31, 2013 with a width of 2.6 miles (4.2 km) at its peak. This is the width found by the National Weather Service based on preliminary data from University of Oklahoma RaxPol mobile radar that also sampled winds of 296 mph (476 km/h) which was used to upgrade the tornado to EF5.[18] The radar measurement was later dismissed and the tornado was rated EF3 based on damage.[19] However, a possible contender for the widest tornado as measured by radar was the F4 Mulhall tornado in north-central Oklahoma which occurred during the 1999 Oklahoma tornado outbreak. The diameter of the maximum winds (over 110 mph (49 m/s)) was over 5,200 feet (1,600 m) as measured by a DOW radar. Although the tornado passed largely over rural terrain, the width of the wind swath capable of producing damage was as wide as 4 mi (6.4 km).[20][21]
The F4 Hallam, Nebraska tornado during the outbreak of May 22, 2004 was the previous official record holder for the widest tornado, surveyed at 2.5 miles (4.0 km) wide. A similar size tornado struck Edmonson, Texas on May 31, 1968, when a damage path width between 2 to 3 miles (3.2 to 4.8 km) was recorded from an F3 tornado.[22]
Highest forward speed[edit]
73 miles per hour (117 km/h) from the Tri-State Tornado (other weak tornadoes have approached or exceeded this speed, but this is the fastest forward movement observed in a major tornado).[1]
Greatest pressure drop[edit]
A pressure deficit of 100 millibars (2.95 inHg) was observed when a violent tornado near Manchester, South Dakota on June 24, 2003 passed directly over an in-situ probe that storm chasing researcher Tim Samaras deployed.[23] In less than a minute, the pressure dropped to 850 millibars (25.10 inHg), which are the greatest pressure decline and the lowest pressure ever recorded at the Earth's surface when adjusted to sea level.[24][25]
On April 21, 2007, a 194-millibar (5.73 inHg) pressure deficit was reported when a tornado struck a storm chasing vehicle in Tulia, Texas.[26] The tornado was relatively weak and caused only EF2 damage as it passed through Tulia.[citation needed] The reported pressure drop far exceeds that which would be expected based on theoretical calculations.[27]
There is a questionable and unofficial citizen's barometer measurement of a 192-millibar (5.67 inHg) drop around Minneapolis in 1904.[28]
Early tornadoes[edit]
Earliest known tornado in Europe[edit]
The earliest recorded tornado in Europe struck Rosdalla, near Kilbeggan, Ireland on April 30, 1054. The earliest known British tornado hit central London on October 23, 1091 and was especially destructive.[29]
Earliest known tornado in the Americas[edit]
An apparent tornado is recorded to have struck Tlatelolco (present day Mexico City), on August 21, 1521, two days before the Aztec capital's fall to Cortés. Many other tornadoes are documented historically within the Basin of Mexico.[30]
First confirmed tornado and first tornado fatality in present-day United States[edit]
August 1671 - Rehoboth, Massachusetts[31][32]
July 8, 1680 - Cambridge, Massachusetts - 1 dead[1][33]
Exceptional tornado droughts[edit]
Longest span without a tornado rated F5 or EF5[edit]
Before the Greensburg EF5 tornado on May 4, 2007, it had been 8 years and one day since the US had had a confirmed F5 or EF5 tornado. The last confirmed F5 or EF5 hit southern Oklahoma City and surrounding communities during the May 3, 1999 event. This is the longest interval without an F5 or EF5 tornado since official records began in 1950.
Exceptional survivors[edit]
Longest distance carried by a tornado[edit]
Matt Suter of Fordland, Missouri holds the record for the longest-known distance traveled by anyone picked up by a tornado who lived to tell about it. On March 12, 2006 he was carried 1,307 feet (398 m), 13 feet (4.0 m) shy of one-quarter mile (400 m), according to National Weather Service measurements.[34][35]
Exceptional coincidences[edit]
Codell, Kansas[edit]
The small town of Codell, Kansas, was hit by a tornado on the same date (May 20) three consecutive years: 1916, 1917, and 1918.[36] The U.S. has about 100,000 thunderstorms a year; less than one percent produce a tornado. The odds of this coincidence occurring again is extremely small.
Tanner/Harvest, Alabama[edit]
Tanner, a small town in northern Alabama, was hit by an F5 tornado on April 3, 1974 and was struck again 45 minutes later by a second F5 (however the rating is disputed and it may have been high-end F4), demolishing what remained of the town. 37 years later, on April 27, 2011 (the largest and deadliest outbreak since 1974), Tanner was hit yet again by the EF5 2011 Hackleburg–Phil Campbell, Alabama tornado, which produced high-end EF4 damage in the southern portion of town. The suburban community of Harvest, Alabama, just to the north, also sustained major impacts from all three Tanner tornadoes, and was also hit by destructive tornadoes in 1995 and 2012.
Moore, Oklahoma[edit]
The Oklahoma City suburb of Moore was hit by devastating tornadoes in 1973, 1999, 2003, 2010, and 2013, five of which were of F4/EF4 strength or greater, although it was determined that the tornado in 2003 caused no F4 damage within Moore itself, but in areas to its northeast. The 1999 and 2013 events were rated F5 and EF5, respectively. In total, about 20 tornadoes have struck within the immediate vicinity of Moore since 1890.[37]
Tuscaloosa, Alabama[edit]
The college town of Tuscaloosa, Alabama was directly hit by killer tornadoes in 1932, 1975, 1997, 2000, and 2011, all but one of which were rated F4 or EF4 (the 1997 tornado was rated F2). The 2011 tornado went on to devastate parts of Birmingham, Alabama.
Birmingham, Alabama[edit]
The northwestern suburbs of Birmingham, Alabama have been devastated by violent and deadly tornadoes in 1954, 1977, 1998, and 2011. The 1977 and 1998 tornadoes were rated F5, and the 1954 and 2011 tornadoes were rated F4 and EF4. The suburb of McDonald Chapel was hit directly by the 1956, 1998, and 2011 tornadoes.
St. Louis, Missouri[edit]
Throughout history, the Greater St. Louis area has been hit by destructive and deadly tornado numerous times, most notably in 1871, 1896, 1927, 1959, 1967, and 2011. The 1896 tornado killed 255 people, and was the third deadliest in American history, and the 1896 tornado was the costliest whereas as the 1927 tornado was the second costliest (adjusted for inflation and increasing population). Additionally, the first and second most costly hailstorms also struck St. Louis on 10 April 2001 and 28 April 2012, respectively, with the former causing more damage in real dollars than the 1999 Oklahoma City tornado did.
McConnell AFB/Haysville, Kansas[edit]
The southern portions of the Wichita, KS Metropolitan Statistical Area, particularly the suburb of Haysville and nearby McConnell Air Force Base, have been hit by destructive tornadoes in 1991, 1999, and 2012. A violent tornado on April 26, 1991 went on to strike nearby Andover at F5 strength, killing 17 people. Remarkably, an F3 tornado followed a very similar path through the area the next month, causing an additional $1,000,000 in damage. The 2012 tornado followed a path that was almost identical to both of the 1991 tornadoes.
See also[edit]
Weather records
List of tropical cyclone extremes
Tornado myths
List of F5 and EF5 tornadoes
List of tornadoes and tornado outbreaks
List of tornado-related deaths at schools
References[edit]
1.^ Jump up to: a b c d e f Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991: A Chronology and Analysis of Events. St. Johnsbury, VT: The Tornado Project of Environmental Films. ISBN 1-879362-03-1.
2.Jump up ^ Brooks, Harold E.; Doswell, Charles A, III (September 2000). "Normalized Damage from Major Tornadoes in the United States: 1890–1999". Retrieved 2007-02-28.
3.Jump up ^ Paul, Bhuiyan (2004). "The April 2004 Tornado in North-Central Bangladesh: A Case for Introducing Tornado Forecasting and Warning Systems" (PDF). Retrieved 2006-08-17.
4.Jump up ^ Hoxit, Lee R; Chappell, Charles F (October 1975). "Tornado Outbreak of April 3–4, 1974; Synoptic Analysis" (PDF). National Oceanic and Atmospheric Administration. Retrieved 2007-03-02.
5.Jump up ^ http://wmo.asu.edu/tornado-largest-tornado-outbreak
6.Jump up ^ "April 2011 tornado information". NOAA. Retrieved 2011-05-03.
7.Jump up ^ Schneider, Russell; H.E. Brooks, J.T. Schaefer (October 2004). "Tornado Outbreak Day Sequences: historic events and climatology (1875-2003)". 22nd Conf Severe Local Storms. Hyannis, MA: American Meteorological Society.
8.Jump up ^ Edwards, Roger (2012). "Tropical Cyclone Tornadoes: A Review of Knowledge in Research and Prediction". E-Journal of Severe Storms Meteorology 7 (6): 3. Retrieved 2013-05-22.
9.Jump up ^ Grazulis, Tom (2000). "Tornadoes in Bangladesh". Worldwide Tornadoes. The Tornado Project.
10.Jump up ^ Brooks, Harold E.; Charles A. Doswell III (February 2001). "Normalized Damage from Major Tornadoes in the United States: 1890–1999". Weather and Forecasting (American Meteorological Society) 16 (1): 168–176. Bibcode:2001WtFor..16..168B. doi:10.1175/1520-0434(2001)016<0168:NDFMTI>2.0.CO;2.
11.Jump up ^ Wurman, Joshua (2007). "Doppler On Wheels". Center for Severe Weather Research.
12.Jump up ^ By, Forecast. "Capital Weather Gang". The Washington Post.
13.Jump up ^ Wright, Celine (June 4, 2013). "Discovery Channel to air special for fallen 'Storm Chasers'". Los Angeles Times.
14.Jump up ^ Bluestein, Howard B.; J.G. Ladue, H. Stein, D. Speheger, W.P. Unruh (August 1993). "Doppler Radar Wind Spectra of Supercell Tornadoes". Monthly Weather Review (American Meteorological Society) 121 (8): 2200–22. Bibcode:1993MWRv..121.2200B. doi:10.1175/1520-0493(1993)121<2200:DRWSOS>2.0.CO;2.
15.Jump up ^ Johns, Robert H.; D. W. Burgess, C. A. Doswell III, M. S. Gilmore, J. A. Hart, and S. F. Piltz (2013). "The 1925 Tri-State Tornado Damage Path and Associated Storm System". E-Journal of Severe Storms Meteorology 8 (2).
16.Jump up ^ Grazulis, Thomas P. (2001). The Tornado: Nature's Ultimate Windstorm. Norman, OK: University of Oklahoma Press. ISBN 0-8061-3258-2.
17.Jump up ^ Martinelli, Jason T. (August 2007). "A detailed analysis of an extremely long-tracked supercell". Preprints of the 33rd Conference on Radar Meteorology. Cairns, Australia: American Meteorological Society and Australian Bureau of Meteorology Research Centre.
18.Jump up ^ "Central Oklahoma Tornadoes and Flash Flooding - May 31, 2013". National Weather Service Norman Oklahoma. 2013. Retrieved 2013-06-04.
19.Jump up ^ "Event Details". National Climatic Data Center. Retrieved 1 October 2013.
20.Jump up ^ Wurman, Joshua; C. Alexander; P. Robinson; Y. Richardson (January 2007). "Low-Level Winds in Tornadoes and Potential Catastrophic Tornado Impacts in Urban Areas". B. Am. Meteorol. Soc. 88 (1): 31–46. Bibcode:2007BAMS...88...31W. doi:10.1175/BAMS-88-1-31.
21.Jump up ^ Lee, Wen-Chau; J. Wurman (2005). "Diagnosed Three-Dimensional Axisymmetric Structure of the Mulhall Tornado on 3 May 1999". J. Atmos. Sci. 62 (7): 2379–93. Bibcode:2005JAtS...62.2373L. doi:10.1175/JAS3489.1.
22.Jump up ^ "May 1968 Storm Data". National Climatic Data Center.
23.Jump up ^ Lee, Julian J.; T. P. Samaras; C. R. Young (October 2004). "Pressure Measurements at the ground in an F-4 tornado". 22nd Conf Severe Local Storms. Hyannis, Massachusetts: American Meteorological Society.
24.Jump up ^ "World: Lowest Sea Level Air Pressure (excluding tornadoes)". World Weather / Climate Extremes Archive. Arizona State University.
25.Jump up ^ Cerveny, Randall S.; J. Lawrimore; R. Edwards; C. Landsea (2007). "Extreme Weather Records: Compilation, Adjudication, and Publication". B. Am. Meteorol. Soc. 88 (6): 853–60. doi:10.1175/BAMS-88-6-853.
26.Jump up ^ Blair, Scott F.; D.R. Deroche, A.E. Pietrycha (2008). "In Situ Observations of the 21 April 2007 Tulia, Texas Tornado". Electronic Journal of Severe Storms Meteorology 3 (3): 1–27.
27.Jump up ^ Lee, W.-C.; J. Wurman (Jul 2005). "The diagnosed structure of the Mulhall tornado". J. Atmos. Sci. 62 (7): 2373–93. Bibcode:2005JAtS...62.2373L. doi:10.1175/JAS3489.1.
28.Jump up ^ Samaras, Tim M. (October 2004). "A historical perspective of In-Situ observations within Tornado Cores". Preprints of the 22nd Conference on Severe Local Storms. Hyannis, MA: American Meteorological Society.
29.Jump up ^ British & European Tornado Extremes
30.Jump up ^ Fuentes, Oscar Velasco (November 2010). "The Earliest Documented Tornado in the Americas: Tlatelolco, August 1521". Bulletin of the American Meteorological Society 91 (11): 1515–23. Bibcode:2010BAMS...91.1515F. doi:10.1175/2010BAMS2874.1.
31.Jump up ^ Grazulis, Thomas P. (2001). The Tornado: Nature's Ultimate Windstorm. Norman, OK: University of Oklahoma Press. ISBN 0-8061-3258-2.
32.Jump up ^ Erck, Amy (December 26, 2005). "Answers archive: Tornado history, climatology". USA Today Weather (USA Today). Retrieved 9 July 2012.
33.Jump up ^ Baker, Tim. "Tornado History". tornadochaser.net. Retrieved 9 July 2012.
34.Jump up ^ "Mo. Teen Survives Tornado, Confronts Media Storm". USA Today. March 22, 2006. Retrieved May 25, 2010.
35.Jump up ^ HE SURVIVED A RIDE IN A TORNADO !
36.Jump up ^ "Tornado Climatology". A SEVERE WEATHER PRIMER: Questions and Answers about TORNADOES.
37.Jump up ^ "Moore, Oklahoma Tornadoes (1890-Present)". National Weather Service Norman Oklahoma. 2013. Retrieved 2013-06-05.
External links[edit]
More on tornadoes: Records, the Fujita scale, and our observations by Chuck Doswell
Tornado Records from the Global Weather & Climate Extremes (World Meteorological Organization)
 


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Lists of weather records
Lists of superlatives






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Cultural significance of tornadoes
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"A single experience of this awful convulsion of the elements suffices to fasten the memory of its occurrence upon the mind with such a dreadful force that no effort can efface the remembrance of it. The destructive violence of this storm exceeds in its power, fierceness, and grandeur all other phenomena of the atmosphere."
John Park Finley, Tornadoes, 1887
Tornado damage to human-made structures is a result of the high wind velocity and windblown debris. Tornadic winds have been measured in excess of 300 mph (480 km/h). Tornadoes are a serious hazard to life and limb. As such, people in tornado-prone areas often adopt plans of action in case a tornado approaches.


Contents  [hide]
1 Tornadoes in society
2 Motion pictures with a tornado theme
3 See also
4 References

Tornadoes in society[edit]



 Cyclone as metaphor for political change in the 1894 United States elections; the farm woman taking shelter is labeled 'Democratic Party'. Puck magazine (1894)
Storm cellars are often used as a means of shelter in case of tornadoes or tropical cyclones. Common in tornado-prone areas, they have been around for more than 100 years—even referenced in the famous 1930s film The Wizard of Oz. Consisting either of a simple underground room, or an elaborate above-ground bunker, they are usually small rooms, designed to keep debris from entering and causing injury. When properly constructed, they can survive an EF5 tornado. While it is unknown how many lives have been saved by storm cellars, the number is undoubtedly high.[1]
Some individuals and hobbyists, known as storm chasers, enjoy pursuing thunderstorms and tornadoes to explore their many visual and scientific aspects. Attempts have been made by some storm chasers from educational and scientific institutions to drop probes in the path of oncoming tornadoes in an effort to analyze the interior of the storms, but only about five drops have been successful since around 1990.
Due to the relative rarity and large scale of destructive power that tornadoes possess, their occurrence or the possibility that they may occur can often create what could be considered sensationalism in their reporting. This results in so-called weather wars, in which competing local media outlets, particularly TV news stations, engage in continually escalating technological one-upsmanship and drama in order to increase their market share. This is especially evident in tornado-prone markets, such as those in the Great Plains.
According to Environment Canada, the chances of being killed by a tornado are 12 million to 1 (12,000,000:1). One may revise this yearly and/or regionally, but the probability may be factually stated to be low. Regardless, tornadoes cause millions of dollars in damage, both economic and physical, many deaths, and hundreds of injuries every year.[2][3] The tornado has been used by cartoonists for over 100 years as a metaphor for political upheaval. The storm cellar has also been used as a metaphor for seeking safety, as shown in the cartoon from 1894 at right.
According to political interpretations of The Wonderful Wizard of Oz, the tornado takes Dorothy to a utopia, the Land of Oz, and kills the Wicked Witch of the East, who had oppressed "the little people", the Munchkins.[4]
A 1960s advertising campaign for the household cleaner, Ajax, claimed the product "Cleans like a white tornado".[5]
Numerous athletic teams across the United States employ a tornado for their mascot. There are 111 high schools and colleges that use "Tornados," or a variant, as their team nicknames. [6]



Motion pictures with a tornado theme[edit]
The Wizard of Oz, 1939
Twister (1989 film)
Mr. and Mrs. Bridge, 1990
Night of the Twisters (1996), the first original motion picture made for The Family Channel
Tornado!, a made-for-TV movie starring Bruce Campbell and Shannon Sturges, released on May 7, 1996
Twister (1996 film)
Storm Chasers: Revenge of the Twister, a 1998 made-for-TV movie
Atomic Twister (TV), 2001
The Day After Tomorrow, 2004
Category 7: The End of the World, 2005
Perfect Disaster: Super Tornado (Discovery Channel), premiered on March 19, 2006
Tornado Glory (PBS), 2006
NYC: Tornado Terror, 2008 movie
Blown Away (song), 2012 Carrie Underwood's music video features a tornado
See also[edit]
List of tornadoes and tornado outbreaks
Tornado myths
References[edit]
1.Jump up ^ "Shelter weathers deadly Okla. tornadoes". USA Today. 2005-05-20. Retrieved 2010-04-30.
2.Jump up ^ Data from the Storm Prediction Center archives, which are accessible through SeverePlot, free software created and maintained by John Hart, lead forecaster for the SPC.
3.Jump up ^ Environment Canada (2004). "Tornadoes". Retrieved 2007-01-17.
4.Jump up ^ Quentin P. Taylor (2004-12-02). "Money and Politics in the Land of Oz". The Independent Institute. Retrieved 2006-10-24.
5.Jump up ^ "Ajax washing liquid". Retrieved 2007-01-25.
6.Jump up ^ "Team Mascots". Retrieved 2012-03-05.
 


Categories: Tornado


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Tornado intensity and damage
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 Tornado damage to a house in Oklahoma County, Oklahoma hit during the Early-May 2010 tornado outbreak.
The Fujita scale and the Enhanced Fujita Scale rate tornadoes by damage caused. The Enhanced Fujita Scale was an upgrade to the older Fujita scale, with engineered (by expert elicitation) wind estimates and better damage descriptions, but was designed so that a tornado rated on the Fujita scale would receive the same numerical rating. An EF0 tornado will probably damage trees but not substantial structures, whereas an EF5 tornado can rip buildings off their foundations leaving them bare and even deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating.
Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes. The association with track length and duration also varies, although longer track tornadoes tend to be stronger.[1] In the case of violent tornadoes, only a small portion of the path area is of violent intensity, most of the higher intensity is from subvortices.[2] In the United States, 80% of tornadoes are EF0 and EF1 (T0 through T3) tornadoes. The rate of occurrence drops off quickly with increasing strength—less than 1% are violent tornadoes(EF4, T8 or stronger).[3]


Contents  [hide]
1 History of tornado intensity measurements
2 Typical intensity
3 Typical damage
4 See also
5 References
6 Further reading

History of tornado intensity measurements[edit]
For many years, before the advent of Doppler radar, scientists had nothing more than educated guesses as to the speed of the winds in a tornado. The only evidence indicating the wind speeds found in the tornado was the damage left behind by tornadoes which struck populated areas. Some believed they reach 400 mph (640 km/h), others thought they might exceed 500 mph (800 km/h), and perhaps even be supersonic. One can still find these incorrect guesses in some old (until the 1960s) literature, such as the original Fujita Intensity Scale developed by Dr. Tetsuya Theodore Fujita in the early '70s. However, one can find accounts [1] (be sure to scroll down) of some remarkable work done in this field by a U.S. Army soldier, Sergeant John Park Finley.




 A diagram of the Fujita scale as it relates to the Beaufort scale and the Mach number scale.
In 1971, Dr. Tetsuya Theodore Fujita introduced the idea for a scale of tornado winds. With the help of colleague Allen Pearson, he created and introduced what came to be called the Fujita scale in 1973. This is what the F stands for in F1, F2, etc. The scale was based on a relationship between the Beaufort scale and the Mach number scale; the low end of F1 on his scale corresponds to the low end of B12 on the Beaufort scale, and the low end of F12 corresponds to the speed of sound at sea level, or Mach 1. In practice, tornadoes are only assigned categories F0 through F5.
The TORRO scale, created by the Tornado and Storm Research Organisation (TORRO), was developed in 1974 and published a year later. The TORRO scale has 12 levels, which cover a broader range with tighter graduations. It ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. T0-T1 roughly correspond to F0, T2-T3 to F1, and so on. While T10+ would be approximately an F5, the highest tornado rated to date on the TORRO scale was a T8.[4][5] There is some debate as to the usefulness of the TORRO scale over the Fujita scale—while it may be helpful for statistical purposes to have more levels of tornado strength, often the damage caused could be created by a large range of winds, rendering it hard to narrow the tornado down to a single TORRO scale category.
Research conducted in the late 1980s and 1990s suggested that, even with the implication of the Fujita scale, tornado winds were notoriously overestimated, especially in significant and violent tornadoes. Because of this, in 2006, the American Meteorological Society introduced the Enhanced Fujita Scale, to help assign realistic wind speeds to tornado damage. The scientists specifically designed the scale so that a tornado assessed on the Fujita scale and the Enhanced Fujita scale would receive the same ranking. The EF-scale is more specific in detailing the degrees of damage on different types of structures for a given wind speed. While the F-scale goes from F0 to F12 in theory, the EF-scale is capped at EF5, which is defined as "winds ≥ 200 mph (≥ 320 km/h)".[6] In the United States, the Enhanced Fujita scale went into effect on February 2, 2007 for tornado damage assessments and the Fujita scale is no longer used.
The first observation which confirmed that F5 winds could occur happened on April 26, 1991. A tornado near Red Rock, Oklahoma was monitored by scientists using a portable Doppler radar, an experimental radar device that measures wind speed. Near the tornado's peak intensity, they recorded a wind speed of 115–120 m/s (257-268 mph or 414–432 km/h). Though the portable radar had uncertainty of ± 5–10 m/s (± 11-22 mph or ± 18–36 km/h), this reading was probably within the F5 range, confirming that tornadoes were capable of violent winds found nowhere else on earth.
Eight years later, during the 1999 Oklahoma tornado outbreak of May 3, 1999, another scientific team was monitoring an exceptionally violent tornado (one which would eventually kill 36 people in the area near Moore, Oklahoma). At about 7:00 pm, they recorded one measurement of 301±20 mph (484±32 km/h),[7] 50 mph (80 km/h) faster than the previous record. Though this reading is just short of the theoretical F6 rating, the measurement was taken more than 100 feet (30 m) in the air, where winds are typically stronger than at the surface.[citation needed] In rating tornadoes, only surface wind speeds, or the wind speeds indicated by the damage resulting from the tornado, are taken into account. Also, in practice, the F6 rating is not used.
While scientists have long theorized that extremely low pressures might occur in the center of tornadoes, there were no measurements to confirm it. A few home barometers had survived close passes by tornadoes, recording values as low as 24 in Hg (810 mbar), but these measurements were highly uncertain.[8] However, on June 24, 2003, a group of researchers successfully dropped devices called "turtles" into an F4 tornado near Manchester, South Dakota, one of which measured a pressure drop of more than 100 mbar as the tornado passed directly overhead.[9] Still, tornadoes are widely varied, so meteorologists are still conducting research to determine if these values are typical or not.
Typical intensity[edit]



 An example of E/F0 damage. The only significant damage to structures in this picture was caused by falling tree branches. Even though well-built structures are typically unscathed by E/F0 tornadoes, falling trees and tree branches can injure and kill people, even inside a sturdy structure.


 An example of E/F1 damage. E/F1 tornadoes cause major damage to mobile homes and automobiles, and can cause minor structural damage to well-constructed homes. This unanchored wood-frame home sustained major roof damage, and was pushed from its foundation while remaining intact.
Further information: Fujita scale
In the United States, F0 and F1 (T0 through T3) tornadoes account for 80% of all tornadoes. The rate of occurrence drops off quickly with increasing strength—violent tornadoes (stronger than F4, T8), account for less than 1% of all tornado reports.[3] Worldwide, strong tornadoes account for an even smaller percentage of total tornadoes. Violent tornadoes are extremely rare outside of the United States, Canada and Bangladesh.
F5 and EF5 tornadoes are rare, occurring on average once every few years. A F5 tornado was reported Elie, Manitoba Tornado in Canada, on June 22, 2007. Before that, the last confirmed F5 was the 1999 Bridge Creek–Moore tornado, which killed 36 people on May 3, 1999.[10] Nine EF5 tornadoes have occurred in the United States, in Greensburg, Kansas on May 4, 2007; Parkersburg, Iowa on May 25, 2008; Smithville, Mississippi, Philadelphia, Mississippi, Hackleburg, Alabama and Rainsville, Alabama (four separate tornadoes) on April 27, 2011; Joplin, Missouri on May 22, 2011 and El Reno, Oklahoma on May 24, 2011. On May 20, 2013 a confirmed EF5 tornado again struck Moore, Oklahoma.
Typical damage[edit]
Further information: Enhanced Fujita scale
Tornado rating classifications[2][11][12]

F0
 EF0
F1
 EF1
F2
 EF2
F3
 EF3
F4
 EF4
F5
 EF5
Weak Strong Violent
 Significant
 Intense



 An example of E/F2 damage. At this intensity, tornadoes have a more significant impact on well-built structures, removing the roofs, and collapsing some exterior walls of poorly built structures. E/F2 tornadoes are capable of completely destroying mobile homes, and generating large amounts of flying debris. This frail wood-frame home sustained major structural damage, and it was moved slightly off its foundation, with its roof completely gone. A mobile home or car is a very poor shelter, even during severe thunderstorms which do not contain a tornado.


 An example of E/F3 damage. Here, the roof and all but some inner walls of this brick home have been demolished. While taking shelter in a basement, cellar, or inner room improves your odds of surviving a tornado drastically, occasionally even this is not enough. E/F3 and stronger tornadoes only account for about 6% of all tornadoes in the United States, and yet since 1980 they have accounted for more than 75% of tornado-related deaths.


 An example of E/F4 damage, with brick homes reduced to piles of rubble. Above-ground structures are almost completely vulnerable to E/F4 tornadoes, which level well-built structures (including stone and brick buildings), toss heavy vehicles through the air, and uproot trees, turning them into flying missiles.


 An example of E/F5 damage. These tornadoes cause incredible and complete destruction, obliterating and sweeping away almost anything in their paths, including those sheltering in open basements. Fortunately, they are extremely rare, and even a tornado rated as E/F5 usually only produces E/F5 damage across a relatively small portion of the damage path (with F4-F0 damage zones surrounding the central E/F5 core).[13] While isolated examples exist of people surviving E/F5 impacts in their homes—one survivor of the Jarrell F5 sheltered in a bathtub and was miraculously blown to safety as her house disintegrated[14]—surviving an E/F5 impact outside of a robust and properly constructed underground storm shelter is statistically unlikely. For example, every member of two separate families were killed while sheltering in their well-built homes during the same F5 in Jarrell and at least one resident sheltering in his basement was swept out to his death during the Parkersburg EF5.
A typical tornado has winds of 110 mph (175 km/h) or less, is approximately 250 feet (75 m) across, and travels a mile (1.6 km) or so before dissipating. However, tornadic behavior is extremely variable; these figures represent only statistical probability.
Two tornadoes that look almost exactly the same can produce drastically different effects. Also, two tornadoes which look very different can produce similar damage. This is due to the fact that tornadoes form by several different mechanisms, and also that they follow a life cycle which causes the same tornado to change in appearance over time. People in the path of a tornado should never attempt to determine its strength as it approaches. Between 1997 and 2005 in the United States, 38 people were killed by EF1 tornadoes, and 3 were killed by EF0 tornadoes.[15] Even the weakest tornado can kill.
Weak tornadoes
The vast majority of tornadoes are designated EF1 or EF0, also known as "weak" tornadoes. However, weak is a relative term for tornadoes, as even these can cause significant damage. F0 and F1 tornadoes are typically short-lived—since 1980 almost 75% of tornadoes rated weak stayed on the ground for one mile (1.6 km) or less.[10] However, in this time, they can cause both damage and fatalities.
EF0 (T0-T1) damage is characterized by superficial damage to structures and vegetation. Well-built structures are typically unscathed, sometimes sustaining broken windows, with minor damage to roofs and chimneys. Billboards and large signs can be knocked down. Trees may have large branches broken off, and can be uprooted if they have shallow roots. Any tornado that is confirmed but causes no damage (i.e. remains in open fields) is always rated EF0 as well.
EF1 (T2-T3) damage has caused significantly more fatalities than that caused by EF0 tornadoes. At this level, damage to mobile homes and other temporary structures becomes significant, and cars and other vehicles can be pushed off the road or flipped. Permanent structures can suffer major damage to their roofs.
Significant tornadoes
EF2 (T4-T5) tornadoes are the lower end of "significant", and yet are stronger than most tropical cyclones (though tropical cyclones affect a much larger area and their winds take place for a much longer duration). Well-built structures can suffer serious damage, including roof loss, and collapse of some exterior walls may occur at poorly built structures. Mobile homes, however, are totally destroyed. Vehicles can be lifted off the ground, and lighter objects can become small missiles, causing damage outside of the tornado's main path. Wooded areas will have a large percentage of their trees snapped or uprooted.
EF3 (T6-T7) damage is a serious risk to life and limb and the point at which a tornado statistically becomes significantly more destructive and deadly. Few parts of affected buildings are left standing; well-built structures lose all outer and some inner walls. Unanchored homes are swept away, and homes with poor anchoring may collapse entirely. Small vehicles and similarly sized objects are lifted off the ground and tossed as projectiles. Wooded areas will suffer almost total loss of vegetation, and some tree debarking may occur. Statistically speaking, EF3 is the maximum level that allows for reasonably effective residential sheltering in place in a first floor interior room, closest to the center of the house (the most widespread tornado sheltering procedure in America for those with no basement).
Violent tornadoes
EF4 (T8-T9) damage typically results in a total loss of the affected structure. Well-built homes are reduced to a short pile of medium-sized debris on the foundation. Homes with poor or no anchoring will be swept completely away. Large, heavy vehicles, including airplanes, trains, and large trucks, can be pushed over, flipped repeatedly or picked up and thrown. Large, healthy trees are entirely debarked and snapped off close to the ground or uprooted altogether and turned into flying projectiles. Passenger cars and similarly sized objects can be picked up and flung for considerable distances. EF4 damage can be expected to level even the most robustly built homes, making the common practice of sheltering in an interior room on the ground floor of a residence insufficient to ensure survival. A storm shelter, reinforced basement or other subterranean shelter is considered necessary to provide any reasonable expectation of safety against EF4 damage.
EF5 (T10+) damage represents the upper limit of tornado power, and destruction is almost always total. An EF5 tornado pulls well-built, well-anchored homes off their foundations and into the air before obliterating them, flinging the wreckage for miles and sweeping the foundation clean. Large, steel reinforced structures such as schools are completely leveled. Tornadoes of this intensity tend to shred and scour low-lying grass and vegetation from the ground. Very little recognizable structural debris is generated by EF5 damage, with most materials reduced to a coarse mix of small, granular particles and dispersed evenly across the tornado's damage path. Large, multi-ton steel frame vehicles and farm equipment are often mangled beyond recognition and deposited miles away or reduced entirely to unrecognizable component parts. The official description of this damage highlights the extreme nature of the destruction, noting that "incredible phenomena will occur"; historically, this has included such awesome displays of power as twisting skyscrapers, levelling entire communities, and stripping asphalt from roadbeds. Despite their relative rarity, the damage caused by EF5 tornadoes represents a disproportionately extreme hazard to life and limb— since 1950 in the United States, only 58 tornadoes (0.1% of all reports) have been designated F5 or EF5, and yet these have been responsible for more than 1300 deaths and 14,000 injuries (21.5% and 13.6%, respectively).[10][16]
See also[edit]
Tornado
Tornado records
Wind engineering
References[edit]
1.Jump up ^ Brooks, Harold E. (2004-04-01). "On the Relationship of Tornado Path Length and Width to Intensity". Weather and Forecasting: Vol. 19, No. 2. pp. 310–319. Retrieved 2007-04-06.
2.^ Jump up to: a b Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991. St. Johnsbury, VT: The Tornado Project of Environmental Films. ISBN 1-879362-03-1.
3.^ Jump up to: a b Edwards, Moller, Purpura et al. (2005). "Basic Spotters’ Field Guide" (PDF). US Department of Commerce, National Weather Service. Retrieved 2006-11-01.
4.Jump up ^ Meaden, Dr. Terence (1985). "A Brief History of TORRO (to 1985)". Tornado and Storm Research Organisation (TORRO). Retrieved 2006-11-01.
5.Jump up ^ Various. "British Weather Extremes Summary". TORRO. Retrieved 2006-11-02.
6.Jump up ^ Edwards, Roger (2006-04-04). "The Online Tornado FAQ". Storm Prediction Center. Retrieved 2006-09-08.
7.Jump up ^ Center for Severe Weather Research (2006). "Doppler On Wheels". Retrieved 2006-12-29.
8.Jump up ^ Lyons, Walter A. The Handy Weather Answer Book. Detroit, MI: Visible Ink Press, 1997.
9.Jump up ^ Chasing Tornadoes @ National Geographic Magazine
10.^ Jump up to: a b c Data from the Storm Prediction Center archives, which are accessible through SvrPlot, free software created and maintained by John Hart, lead forecaster for the SPC.
11.Jump up ^ The Fujita Scale of Tornado Intensity
12.Jump up ^ Severe Thunderstorm Climatology
13.Jump up ^ WW2010 Project. "Tornadoes". University of Illinois at Urbana-Champaign Department of Atmospheric Sciences. Retrieved 2006-11-01.
14.Jump up ^ Wolf, Richard (1997-11-28). "Twister's wounds run deep". USA Today. Retrieved 2006-11-01.
15.Jump up ^ "Climatological or Past Storm Information and Archived Data." Storm Prediction Center. 2006.
16.Jump up ^ http://www.norman.noaa.gov/nsww/wp-content/uploads/2012/03/LaDue_NSWW2012.pdf
Edwards, Roger; J. G. LaDue; J. T. Ferree; K. Scharfenberg; C. Maier; W. L. Coulbourne (2013). "Tornado Intensity Estimation: Past, Present, and Future". Bull. Amer. Meteor. Soc. 94 (5): 641–53. doi:10.1175/BAMS-D-11-00006.1.
Agee, Ernest; S. Childs (2014). "Adjustments in Tornado Counts, F-Scale Intensity, and Path Width for Assessing Significant Tornado Destruction". J. Appl. Meteor. Climatol. 53 (6): 1494–505. doi:10.1175/JAMC-D-13-0235.1.
Further reading[edit]
Feuerstein, Bernold; P. Groenemeijer, E. Dirksen, M. Hubrig, A.M. Holzer, N. Dotzek (Jun 2011). "Towards an improved wind speed scale and damage description adapted for Central Europe". Atmos. Res. 100 (4): 547–64. doi:10.1016/j.atmosres.2010.12.026.
 


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Tornado
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This article is about the weather phenomenon. For other uses, see Tornado (disambiguation).
For the current tornado season, see Tornadoes of 2014.
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Tornado
A tornado on the ground in Chickasha, Oklahoma.
A tornado on the ground in Chickasha, Oklahoma.

Symbol
A large twirling funnel.
Type
Extreme
Comes from what cloud?
Cumulonimbus, Wall, or Funnel.
Effect
Death, injury, damage and destruction of property.



 A tornado near Anadarko, Oklahoma. The funnel is the thin tube reaching from the cloud to the ground. The lower part of this tornado is surrounded by a translucent dust cloud, kicked up by the tornado's strong winds at the surface. The wind of the tornado has a much wider radius than the funnel itself.
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A tornado is a violently rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as twisters or cyclones,[1] although the word cyclone is used in meteorology, in a wider sense, to name any closed low pressure circulation. Tornadoes come in many shapes and sizes, but they are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds less than 110 miles per hour (177 km/h), are about 250 feet (76 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (483 km/h), stretch more than two miles (3.2 km) across, and stay on the ground for dozens of miles (more than 100 km).[2][3][4]
Various types of tornadoes include the landspout, multiple vortex tornado, and waterspout. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud. They are generally classified as non-supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes. These spiraling columns of air frequently develop in tropical areas close to the equator, and are less common at high latitudes.[5] Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirls, and steam devil; downbursts are frequently confused with tornadoes, though their action is dissimilar.
Tornadoes have been observed on every continent except Antarctica. However, the vast majority of tornadoes occur in the Tornado Alley region of the United States, although they can occur nearly anywhere in North America.[6] They also occasionally occur in south-central and eastern Asia, northern and east-central South America, Southern Africa, northwestern and southeast Europe, western and southeastern Australia, and New Zealand.[7] Tornadoes can be detected before or as they occur through the use of Pulse-Doppler radar by recognizing patterns in velocity and reflectivity data, such as hook echoes or debris balls, as well as through the efforts of storm spotters.
There are several scales for rating the strength of tornadoes. The Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale. An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes.[8] Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and assign a rating.[9][10]


Contents  [hide]
1 Etymology
2 Definitions 2.1 Funnel cloud
2.2 Outbreaks and families
3 Characteristics 3.1 Size and shape
3.2 Appearance
3.3 Rotation
3.4 Sound and seismology
3.5 Electromagnetic, lightning, and other effects
4 Life cycle 4.1 Supercell relationship
4.2 Formation
4.3 Maturity
4.4 Dissipation
5 Types 5.1 Multiple vortex
5.2 Waterspout
5.3 Landspout
5.4 Similar circulations 5.4.1 Gustnado
5.4.2 Dust devil
5.4.3 Fire whirls and steam devils

6 Intensity and damage
7 Climatology 7.1 Associations with climate and climate change
8 Detection 8.1 Radar
8.2 Storm spotting
8.3 Visual evidence
9 Extremes
10 Safety
11 Myths and misconceptions
12 Ongoing research
13 Gallery
14 See also
15 References
16 Further reading
17 External links

Etymology
The word tornado is an altered form of the Spanish word tronada, which means "thunderstorm". This in turn was taken from the Latin tonare, meaning "to thunder". It most likely reached its present form through a combination of the Spanish tronada and tornar ("to turn"); however, this may be a folk etymology.[11][12] A tornado is also commonly referred to as a "twister", and is also sometimes referred to by the old-fashioned colloquial term cyclone.[13][14] The term "cyclone" is used as a synonym for "tornado" in the often-aired 1939 film The Wizard of Oz. The term "twister" is also used in that film, along with being the title of the 1996 tornado-related film Twister.
Definitions



 A tornado near Seymour, Texas
A tornado is "a violently rotating column of air, in contact with the ground, either pendant from a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud".[15] For a vortex to be classified as a tornado, it must be in contact with both the ground and the cloud base. Scientists have not yet created a complete definition of the word; for example, there is disagreement as to whether separate touchdowns of the same funnel constitute separate tornadoes.[4] Tornado refers to the vortex of wind, not the condensation cloud.[16][17]
Funnel cloud
Main article: Funnel cloud



 This tornado has no funnel cloud; however, the rotating dust cloud indicates that strong winds are occurring at the surface, and thus it is a true tornado.
A tornado is not necessarily visible; however, the intense low pressure caused by the high wind speeds (as described by Bernoulli's principle) and rapid rotation (due to cyclostrophic balance) usually causes water vapor in the air to condense into cloud droplets due to adiabatic cooling. This results in the formation of a visible funnel cloud or condensation funnel.[18]
There is some disagreement over the definition of funnel cloud and condensation funnel. According to the Glossary of Meteorology, a funnel cloud is any rotating cloud pendant from a cumulus or cumulonimbus, and thus most tornadoes are included under this definition.[19] Among many meteorologists, the funnel cloud term is strictly defined as a rotating cloud which is not associated with strong winds at the surface, and condensation funnel is a broad term for any rotating cloud below a cumuliform cloud.[4]
Tornadoes often begin as funnel clouds with no associated strong winds at the surface, and not all funnel clouds evolve into tornadoes. Most tornadoes produce strong winds at the surface while the visible funnel is still above the ground, so it is difficult to discern the difference between a funnel cloud and a tornado from a distance.[4]
Outbreaks and families
Main articles: Tornado family, tornado outbreak and tornado outbreak sequence
Occasionally, a single storm will produce more than one tornado, either simultaneously or in succession. Multiple tornadoes produced by the same storm cell are referred to as a "tornado family".[20] Several tornadoes are sometimes spawned from the same large-scale storm system. If there is no break in activity, this is considered a tornado outbreak (although the term "tornado outbreak" has various definitions). A period of several successive days with tornado outbreaks in the same general area (spawned by multiple weather systems) is a tornado outbreak sequence, occasionally called an extended tornado outbreak.[15][21][22]
Characteristics
Size and shape



 A wedge tornado, nearly a mile wide, which hit Binger, Oklahoma in 1981
Most tornadoes take on the appearance of a narrow funnel, a few hundred yards (meters) across, with a small cloud of debris near the ground. Tornadoes may be obscured completely by rain or dust. These tornadoes are especially dangerous, as even experienced meteorologists might not see them.[23] Tornadoes can appear in many shapes and sizes.
Small, relatively weak landspouts may be visible only as a small swirl of dust on the ground. Although the condensation funnel may not extend all the way to the ground, if associated surface winds are greater than 40 mph (64 km/h), the circulation is considered a tornado.[16] A tornado with a nearly cylindrical profile and relative low height is sometimes referred to as a "stovepipe" tornado. Large single-vortex tornadoes can look like large wedges stuck into the ground, and so are known as "wedge tornadoes" or "wedges". The "stovepipe" classification is also used for this type of tornado, if it otherwise fits that profile. A wedge can be so wide that it appears to be a block of dark clouds, wider than the distance from the cloud base to the ground. Even experienced storm observers may not be able to tell the difference between a low-hanging cloud and a wedge tornado from a distance. Many, but not all major tornadoes are wedges.[24]



 A rope tornado in its dissipating stage, Tecumseh, Oklahoma.
Tornadoes in the dissipating stage can resemble narrow tubes or ropes, and often curl or twist into complex shapes. These tornadoes are said to be "roping out", or becoming a "rope tornado". When they rope out, the length of their funnel increases, which forces the winds within the funnel to weaken due to conservation of angular momentum.[25] Multiple-vortex tornadoes can appear as a family of swirls circling a common center, or they may be completely obscured by condensation, dust, and debris, appearing to be a single funnel.[26]
In the United States, tornadoes are around 500 feet (150 m) across on average and travel on the ground for 5 miles (8.0 km).[23] However, there is a wide range of tornado sizes. Weak tornadoes, or strong yet dissipating tornadoes, can be exceedingly narrow, sometimes only a few feet or couple meters across. One tornado was reported to have a damage path only 7 feet (2 m) long.[23] On the other end of the spectrum, wedge tornadoes can have a damage path a mile (1.6 km) wide or more. A tornado that affected Hallam, Nebraska on May 22, 2004, was up to 2.5 miles (4.0 km) wide at the ground.[3]
In terms of path length, the Tri-State Tornado, which affected parts of Missouri, Illinois, and Indiana on March 18, 1925, was on the ground continuously for 219 miles (352 km). Many tornadoes which appear to have path lengths of 100 miles (160 km) or longer are composed of a family of tornadoes which have formed in quick succession; however, there is no substantial evidence that this occurred in the case of the Tri-State Tornado.[21] In fact, modern reanalysis of the path suggests that the tornado may have begun 15 miles (24 km) further west than previously thought.[27]
Appearance
Tornadoes can have a wide range of colors, depending on the environment in which they form. Those that form in dry environments can be nearly invisible, marked only by swirling debris at the base of the funnel. Condensation funnels that pick up little or no debris can be gray to white. While traveling over a body of water (as a waterspout), tornadoes can turn very white or even blue. Slow-moving funnels, which ingest a considerable amount of debris and dirt, are usually darker, taking on the color of debris. Tornadoes in the Great Plains can turn red because of the reddish tint of the soil, and tornadoes in mountainous areas can travel over snow-covered ground, turning white.[23]



 Photographs of the Waurika, Oklahoma tornado of May 30, 1976, taken at nearly the same time by two photographers. In the top picture, the tornado is lit with the sunlight focused from behind the camera, thus the funnel appears bluish. In the lower image, where the camera is facing the opposite direction, the sun is behind the tornado, giving it a dark appearance.[28]
Lighting conditions are a major factor in the appearance of a tornado. A tornado which is "back-lit" (viewed with the sun behind it) appears very dark. The same tornado, viewed with the sun at the observer's back, may appear gray or brilliant white. Tornadoes which occur near the time of sunset can be many different colors, appearing in hues of yellow, orange, and pink.[13][29]
Dust kicked up by the winds of the parent thunderstorm, heavy rain and hail, and the darkness of night are all factors which can reduce the visibility of tornadoes. Tornadoes occurring in these conditions are especially dangerous, since only weather radar observations, or possibly the sound of an approaching tornado, serve as any warning to those in the storm's path. Most significant tornadoes form under the storm's updraft base, which is rain-free,[30] making them visible.[31] Also, most tornadoes occur in the late afternoon, when the bright sun can penetrate even the thickest clouds.[21] Night-time tornadoes are often illuminated by frequent lightning.
There is mounting evidence, including Doppler On Wheels mobile radar images and eyewitness accounts, that most tornadoes have a clear, calm center with extremely low pressure, akin to the eye of tropical cyclones. Lightning is said to be the source of illumination for those who claim to have seen the interior of a tornado.[32][33][34]
Rotation
Tornadoes normally rotate cyclonically (when viewed from above, this is counterclockwise in the northern hemisphere and clockwise in the southern). While large-scale storms always rotate cyclonically due to the Coriolis effect, thunderstorms and tornadoes are so small that the direct influence of the Coriolis effect is unimportant, as indicated by their large Rossby numbers. Supercells and tornadoes rotate cyclonically in numerical simulations even when the Coriolis effect is neglected.[35][36] Low-level mesocyclones and tornadoes owe their rotation to complex processes within the supercell and ambient environment.[37]
Approximately 1 percent of tornadoes rotate in an anticyclonic direction in the northern hemisphere. Typically, systems as weak as landspouts and gustnadoes can rotate anticyclonically, and usually only those which form on the anticyclonic shear side of the descending rear flank downdraft (RFD) in a cyclonic supercell.[38] On rare occasions, anticyclonic tornadoes form in association with the mesoanticyclone of an anticyclonic supercell, in the same manner as the typical cyclonic tornado, or as a companion tornado either as a satellite tornado or associated with anticyclonic eddies within a supercell.[39]
Sound and seismology
Tornadoes emit widely on the acoustics spectrum and the sounds are caused by multiple mechanisms. Various sounds of tornadoes have been reported, mostly related to familiar sounds for the witness and generally some variation of a whooshing roar. Popularly reported sounds include a freight train, rushing rapids or waterfall, a nearby jet engine, or combinations of these. Many tornadoes are not audible from much distance; the nature and propagation distance of the audible sound depends on atmospheric conditions and topography.
The winds of the tornado vortex and of constituent turbulent eddies, as well as airflow interaction with the surface and debris, contribute to the sounds. Funnel clouds also produce sounds. Funnel clouds and small tornadoes are reported as whistling, whining, humming, or the buzzing of innumerable bees or electricity, or more or less harmonic, whereas many tornadoes are reported as a continuous, deep rumbling, or an irregular sound of "noise".[40]
Since many tornadoes are audible only when very near, sound is not reliable warning of a tornado. Tornadoes are also not the only source of such sounds in severe thunderstorms; any strong, damaging wind, a severe hail volley, or continuous thunder in a thunderstorm may produce a roaring sound.[41]



 An illustration of generation of infrasound in tornadoes by the Earth System Research Laboratory's Infrasound Program
Tornadoes also produce identifiable inaudible infrasonic signatures.[42]
Unlike audible signatures, tornadic signatures have been isolated; due to the long distance propagation of low-frequency sound, efforts are ongoing to develop tornado prediction and detection devices with additional value in understanding tornado morphology, dynamics, and creation.[43] Tornadoes also produce a detectable seismic signature, and research continues on isolating it and understanding the process.[44]
Electromagnetic, lightning, and other effects
Tornadoes emit on the electromagnetic spectrum, with sferics and E-field effects detected.[43][45][46] There are observed correlations between tornadoes and patterns of lightning. Tornadic storms do not contain more lightning than other storms and some tornadic cells never produce lightning. More often than not, overall cloud-to-ground (CG) lightning activity decreases as a tornado reaches the surface and returns to the baseline level when the tornado lifts. In many cases, intense tornadoes and thunderstorms exhibit an increased and anomalous dominance of positive polarity CG discharges.[47] Electromagnetics and lightning have little or nothing to do directly with what drives tornadoes (tornadoes are basically a thermodynamic phenomenon), although there are likely connections with the storm and environment affecting both phenomena.
Luminosity has been reported in the past and is probably due to misidentification of external light sources such as lightning, city lights, and power flashes from broken lines, as internal sources are now uncommonly reported and are not known to ever have been recorded. In addition to winds, tornadoes also exhibit changes in atmospheric variables such as temperature, moisture, and pressure. For example, on June 24, 2003 near Manchester, South Dakota, a probe measured a 100 mbar (hPa) (2.95 inHg) pressure decrease. The pressure dropped gradually as the vortex approached then dropped extremely rapidly to 850 mbar (hPa) (25.10 inHg) in the core of the violent tornado before rising rapidly as the vortex moved away, resulting in a V-shape pressure trace. Temperature tends to decrease and moisture content to increase in the immediate vicinity of a tornado.[48]
Life cycle



 A sequence of images showing the birth of a tornado. First, the rotating cloud base lowers. This lowering becomes a funnel, which continues descending while winds build near the surface, kicking up dust and other debris. Finally, the visible funnel extends to the ground, and the tornado begins causing major damage. This tornado, near Dimmitt, Texas, was one of the best-observed violent tornadoes in history.
Further information: Tornadogenesis
Supercell relationship
See also: Supercell
Tornadoes often develop from a class of thunderstorms known as supercells. Supercells contain mesocyclones, an area of organized rotation a few miles up in the atmosphere, usually 1–6 miles (2–10 km) across. Most intense tornadoes (EF3 to EF5 on the Enhanced Fujita Scale) develop from supercells. In addition to tornadoes, very heavy rain, frequent lightning, strong wind gusts, and hail are common in such storms.
Most tornadoes from supercells follow a recognizable life cycle. That begins when increasing rainfall drags with it an area of quickly descending air known as the rear flank downdraft (RFD). This downdraft accelerates as it approaches the ground, and drags the supercell's rotating mesocyclone towards the ground with it.[16]
Formation
As the mesocyclone lowers below the cloud base, it begins to take in cool, moist air from the downdraft region of the storm. This convergence of warm air in the updraft, and this cool air, causes a rotating wall cloud to form. The RFD also focuses the mesocyclone's base, causing it to siphon air from a smaller and smaller area on the ground. As the updraft intensifies, it creates an area of low pressure at the surface. This pulls the focused mesocyclone down, in the form of a visible condensation funnel. As the funnel descends, the RFD also reaches the ground, creating a gust front that can cause severe damage a good distance from the tornado. Usually, the funnel cloud begins causing damage on the ground (becoming a tornado) within a few minutes of the RFD reaching the ground.[16]
Maturity
Initially, the tornado has a good source of warm, moist inflow to power it, so it grows until it reaches the "mature stage". This can last anywhere from a few minutes to more than an hour, and during that time a tornado often causes the most damage, and in rare cases can be more than one mile (1.6 km) across. Meanwhile, the RFD, now an area of cool surface winds, begins to wrap around the tornado, cutting off the inflow of warm air which feeds the tornado.[16]
Dissipation
As the RFD completely wraps around and chokes off the tornado's air supply, the vortex begins to weaken, and become thin and rope-like. This is the "dissipating stage", often lasting no more than a few minutes, after which the tornado fizzles. During this stage the shape of the tornado becomes highly influenced by the winds of the parent storm, and can be blown into fantastic patterns.[21][28][29] Even though the tornado is dissipating, it is still capable of causing damage. The storm is contracting into a rope-like tube and, like the ice skater who pulls her arms in to spin faster, winds can increase at this point.[25]
As the tornado enters the dissipating stage, its associated mesocyclone often weakens as well, as the rear flank downdraft cuts off the inflow powering it. Sometimes, in intense supercells, tornadoes can develop cyclically. As the first mesocyclone and associated tornado dissipate, the storm's inflow may be concentrated into a new area closer to the center of the storm. If a new mesocyclone develops, the cycle may start again, producing one or more new tornadoes. Occasionally, the old (occluded) mesocyclone and the new mesocyclone produce a tornado at the same time.
Although this is a widely accepted theory for how most tornadoes form, live, and die, it does not explain the formation of smaller tornadoes, such as landspouts, long-lived tornadoes, or tornadoes with multiple vortices. These each have different mechanisms which influence their development—however, most tornadoes follow a pattern similar to this one.[49]
Types
Multiple vortex
Main article: Multiple-vortex tornado



 A multiple-vortex tornado outside Dallas, Texas on April 2, 1957.
A multiple-vortex tornado is a type of tornado in which two or more columns of spinning air rotate around a common center. A multi-vortex structure can occur in almost any circulation, but is very often observed in intense tornadoes. These vortices often create small areas of heavier damage along the main tornado path.[4][16] This is a distinct phenomenon from a satellite tornado, which is a smaller tornado which forms very near a large, strong tornado contained within the same mesocyclone. The satellite tornado may appear to "orbit" the larger tornado (hence the name), giving the appearance of one, large multi-vortex tornado. However, a satellite tornado is a distinct circulation, and is much smaller than the main funnel.[4]
Waterspout
Main article: waterspout



 A waterspout near the Florida Keys in 1969.
A waterspout is defined by the National Weather Service as a tornado over water. However, researchers typically distinguish "fair weather" waterspouts from tornadic waterspouts. Fair weather waterspouts are less severe but far more common, and are similar to dust devils and landspouts. They form at the bases of cumulus congestus clouds over tropical and subtropical waters. They have relatively weak winds, smooth laminar walls, and typically travel very slowly. They occur most commonly in the Florida Keys and in the northern Adriatic Sea.[50][51][52] In contrast, tornadic waterspouts are stronger tornadoes over water. They form over water similarly to mesocyclonic tornadoes, or are stronger tornadoes which cross over water. Since they form from severe thunderstorms and can be far more intense, faster, and longer-lived than fair weather waterspouts, they are more dangerous.[53] In official tornado statistics, waterspouts are generally not counted unless they affect land, though some European weather agencies count waterspouts and tornadoes together.[4][54]
Landspout
Main article: landspout
A landspout, or dust-tube tornado, is a tornado not associated with a mesocyclone. The name stems from their characterization as a "fair weather waterspout on land". Waterspouts and landspouts share many defining characteristics, including relative weakness, short lifespan, and a small, smooth condensation funnel which often does not reach the surface. Landspouts also create a distinctively laminar cloud of dust when they make contact with the ground, due to their differing mechanics from true mesoform tornadoes. Though usually weaker than classic tornadoes, they can produce strong winds which could cause serious damage.[4][16]
Similar circulations
Gustnado
Main article: gustnado



 A dust devil in Arizona
A gustnado, or gust front tornado, is a small, vertical swirl associated with a gust front or downburst. Because they are not connected with a cloud base, there is some debate as to whether or not gustnadoes are tornadoes. They are formed when fast moving cold, dry outflow air from a thunderstorm is blown through a mass of stationary, warm, moist air near the outflow boundary, resulting in a "rolling" effect (often exemplified through a roll cloud). If low level wind shear is strong enough, the rotation can be turned vertically or diagonally and make contact with the ground. The result is a gustnado.[4][55] They usually cause small areas of heavier rotational wind damage among areas of straight-line wind damage.
Dust devil
Main article: dust devil
A dust devil resembles a tornado in that it is a vertical swirling column of air. However, they form under clear skies and are no stronger than the weakest tornadoes. They form when a strong convective updraft is formed near the ground on a hot day. If there is enough low level wind shear, the column of hot, rising air can develop a small cyclonic motion that can be seen near the ground. They are not considered tornadoes because they form during fair weather and are not associated with any clouds. However, they can, on occasion, result in major damage in arid areas.[23][56]
Fire whirls and steam devils
Main articles: fire whirl and steam devil
Small-scale, tornado-like circulations can occur near any intense surface heat source. Those that occur near intense wildfires are called fire whirls. They are not considered tornadoes, except in the rare case where they connect to a pyrocumulus or other cumuliform cloud above. Fire whirls usually are not as strong as tornadoes associated with thunderstorms. They can, however, produce significant damage.[21] A steam devil is a rotating updraft that involves steam or smoke. Steam devils are very rare. They most often form from smoke issuing from a power plant's smokestack. Hot springs and deserts may also be suitable locations for a steam devil to form. The phenomenon can occur over water, when cold arctic air passes over relatively warm water.[23]

Intensity and damage
Main article: Tornado intensity and damage
See also: Enhanced Fujita scale, Fujita scale and TORRO scale
Tornado rating classifications[21][57]

F0
 EF0
F1
 EF1
F2
 EF2
F3
 EF3
F4
 EF4
F5
 EF5
Weak Strong Violent
 Significant
 Intense
The Fujita scale and the Enhanced Fujita Scale rate tornadoes by damage caused. The Enhanced Fujita (EF) Scale was an update to the older Fujita scale, by expert elicitation, using engineered wind estimates and better damage descriptions. The EF Scale was designed so that a tornado rated on the Fujita scale would receive the same numerical rating, and was implemented starting in the United States in 2007. An EF0 tornado will probably damage trees but not substantial structures, whereas an EF5 tornado can rip buildings off their foundations leaving them bare and even deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler weather radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating.[4][58][59]



 A house displaying EF1 damage. The roof and garage door have been damaged, but walls and supporting structures are still intact.
Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes. The association with track length and duration also varies, although longer track tornadoes tend to be stronger.[60] In the case of violent tornadoes, only a small portion of the path is of violent intensity, most of the higher intensity from subvortices.[21]
In the United States, 80% of tornadoes are EF0 and EF1 (T0 through T3) tornadoes. The rate of occurrence drops off quickly with increasing strength—less than 1% are violent tornadoes (EF4, T8 or stronger).[61] Outside Tornado Alley, and North America in general, violent tornadoes are extremely rare. This is apparently mostly due to the lesser number of tornadoes overall, as research shows that tornado intensity distributions are fairly similar worldwide. A few significant tornadoes occur annually in Europe, Asia, southern Africa, and southeastern South America, respectively.[62]

Climatology
Main article: Tornado climatology



 Areas worldwide where tornadoes are most likely, indicated by orange shading
The United States has the most tornadoes of any country, nearly four times more than estimated in all of Europe, excluding waterspouts.[63] This is mostly due to the unique geography of the continent. North America is a large continent that extends from the tropics north into arctic areas, and has no major east-west mountain range to block air flow between these two areas. In the middle latitudes, where most tornadoes of the world occur, the Rocky Mountains block moisture and buckle the atmospheric flow, forcing drier air at mid-levels of the troposphere due to downsloped winds, and causing the formation of a low pressure area downwind to the east of the mountains. Increased westerly flow off the Rockies force the formation of a dry line when the flow aloft is strong,[64] while the Gulf of Mexico fuels abundant low-level moisture in the southerly flow to its east. This unique topography allows for frequent collisions of warm and cold air, the conditions that breed strong, long-lived storms throughout the year. A large portion of these tornadoes form in an area of the central United States known as Tornado Alley.[6] This area extends into Canada, particularly Ontario and the Prairie Provinces, although southeast Quebec, the interior of British Columbia, and western New Brunswick are also tornado-prone.[65] Tornadoes also occur across northeastern Mexico.[4]
The United States averages about 1,200 tornadoes per year. The Netherlands has the highest average number of recorded tornadoes per area of any country (more than 20, or 0.0013 per sq mi (0.00048 per km2), annually), followed by the UK (around 33, or 0.00035 per sq mi (0.00013 per km2), per year),[66][67] but most are small and cause minor damage. In absolute number of events, ignoring area, the UK experiences more tornadoes than any other European country, excluding waterspouts.[63]



 Intense tornado activity in the United States. The darker-colored areas denote the area commonly referred to as Tornado Alley.
Tornadoes kill an average of 179 people per year in Bangladesh, the most in the world.[68] This is due to high population density, poor quality of construction and lack of tornado safety knowledge, as well as other factors.[68][69] Other areas of the world that have frequent tornadoes include South Africa, the La Plata Basin area, portions of Europe, Australia and New Zealand, and far eastern Asia.[7][70]
Tornadoes are most common in spring and least common in winter, but tornadoes can occur any time of year that favorable conditions occur.[21] Spring and fall experience peaks of activity as those are the seasons when stronger winds, wind shear, and atmospheric instability are present.[71] Tornadoes are focused in the right front quadrant of landfalling tropical cyclones, which tend to occur in the late summer and autumn. Tornadoes can also be spawned as a result of eyewall mesovortices, which persist until landfall.[72]
Tornado occurrence is highly dependent on the time of day, because of solar heating.[73] Worldwide, most tornadoes occur in the late afternoon, between 3 pm and 7 pm local time, with a peak near 5 pm.[74][75][76][77][78] Destructive tornadoes can occur at any time of day. The Gainesville Tornado of 1936, one of the deadliest tornadoes in history, occurred at 8:30 am local time.[21]
Associations with climate and climate change



 U. S. Annual January - December Tornado Count 1976-2011 from NOAA National Climatic Data Center
Associations with various climate and environmental trends exist. For example, an increase in the sea surface temperature of a source region (e.g. Gulf of Mexico and Mediterranean Sea) increases atmospheric moisture content. Increased moisture can fuel an increase in severe weather and tornado activity, particularly in the cool season.[79]
Some evidence does suggest that the Southern Oscillation is weakly correlated with changes in tornado activity, which vary by season and region, as well as whether the ENSO phase is that of El Niño or La Niña.[80]
Climatic shifts may affect tornadoes via teleconnections in shifting the jet stream and the larger weather patterns. The climate-tornado link is confounded by the forces affecting larger patterns and by the local, nuanced nature of tornadoes. Although it is reasonable to suspect that global warming may affect trends in tornado activity,[81] any such effect is not yet identifiable due to the complexity, local nature of the storms, and database quality issues. Any effect would vary by region.[82]
Detection



 Path of a tornado across Wisconsin on August 21, 1857
Main article: Convective storm detection
Rigorous attempts to warn of tornadoes began in the United States in the mid-20th century. Before the 1950s, the only method of detecting a tornado was by someone seeing it on the ground. Often, news of a tornado would reach a local weather office after the storm. However, with the advent of weather radar, areas near a local office could get advance warning of severe weather. The first public tornado warnings were issued in 1950 and the first tornado watches and convective outlooks in 1952. In 1953 it was confirmed that hook echoes are associated with tornadoes.[83] By recognizing these radar signatures, meteorologists could detect thunderstorms probably producing tornadoes from dozens of miles away.[84]
Radar
See also: Pulse-Doppler radar and weather radar
Today, most developed countries have a network of weather radars, which remains the main method of detecting signatures probably associated with tornadoes. In the United States and a few other countries, Doppler weather radar stations are used. These devices measure the velocity and radial direction (towards or away from the radar) of the winds in a storm, and so can spot evidence of rotation in storms from more than a hundred miles (160 km) away. When storms are distant from a radar, only areas high within the storm are observed and the important areas below are not sampled.[85] Data resolution also decreases with distance from the radar. Some meteorological situations leading to tornadogenesis are not readily detectable by radar and on occasion tornado development may occur more quickly than radar can complete a scan and send the batch of data. Also, most populated areas on Earth are now visible from the Geostationary Operational Environmental Satellites (GOES), which aid in the nowcasting of tornadic storms.[86]




 A Doppler on Wheels radar loop of a hook echo and associated mesocyclone in Goshen County, Wyoming on June 5, 2009. Strong mesocyclones show up as adjacent areas of yellow and blue (on other radars, bright red and bright green), and usually indicate an imminent or occurring tornado.
Storm spotting
In the mid-1970s, the U.S. National Weather Service (NWS) increased its efforts to train storm spotters to spot key features of storms which indicate severe hail, damaging winds, and tornadoes, as well as damage itself and flash flooding. The program was called Skywarn, and the spotters were local sheriff's deputies, state troopers, firefighters, ambulance drivers, amateur radio operators, civil defense (now emergency management) spotters, storm chasers, and ordinary citizens. When severe weather is anticipated, local weather service offices request that these spotters look out for severe weather, and report any tornadoes immediately, so that the office can warn of the hazard.
Usually spotters are trained by the NWS on behalf of their respective organizations, and report to them. The organizations activate public warning systems such as sirens and the Emergency Alert System (EAS), and forward the report to the NWS.[87] There are more than 230,000 trained Skywarn weather spotters across the United States.[88]
In Canada, a similar network of volunteer weather watchers, called Canwarn, helps spot severe weather, with more than 1,000 volunteers.[86] In Europe, several nations are organizing spotter networks under the auspices of Skywarn Europe[89] and the Tornado and Storm Research Organisation (TORRO) has maintained a network of spotters in the United Kingdom since 1974.[90]
Storm spotters are needed because radar systems such as NEXRAD do not detect a tornado; merely signatures which hint at the presence of tornadoes.[91] Radar may give a warning before there is any visual evidence of a tornado or imminent tornado, but ground truth from an observer can either verify the threat or determine that a tornado is not imminent.[92] The spotter's ability to see what radar cannot is especially important as distance from the radar site increases, because the radar beam becomes progressively higher in altitude further away from the radar, chiefly due to curvature of Earth, and the beam also spreads out.[85]
Visual evidence



 A rotating wall cloud with rear flank downdraft clear slot evident to its left rear
Storm spotters are trained to discern whether a storm seen from a distance is a supercell. They typically look to its rear, the main region of updraft and inflow. Under the updraft is a rain-free base, and the next step of tornadogenesis is the formation of a rotating wall cloud. The vast majority of intense tornadoes occur with a wall cloud on the backside of a supercell.[61]
Evidence of a supercell comes from the storm's shape and structure, and cloud tower features such as a hard and vigorous updraft tower, a persistent, large overshooting top, a hard anvil (especially when backsheared against strong upper level winds), and a corkscrew look or striations. Under the storm and closer to where most tornadoes are found, evidence of a supercell and likelihood of a tornado includes inflow bands (particularly when curved) such as a "beaver tail", and other clues such as strength of inflow, warmth and moistness of inflow air, how outflow- or inflow-dominant a storm appears, and how far is the front flank precipitation core from the wall cloud. Tornadogenesis is most likely at the interface of the updraft and rear flank downdraft, and requires a balance between the outflow and inflow.[16]
Only wall clouds that rotate spawn tornadoes, and usually precede the tornado by five to thirty minutes. Rotating wall clouds may be a visual manifestation of a low-level mesocyclone. Barring a low-level boundary, tornadogenesis is highly unlikely unless a rear flank downdraft occurs, which is usually visibly evidenced by evaporation of cloud adjacent to a corner of a wall cloud. A tornado often occurs as this happens or shortly after; first, a funnel cloud dips and in nearly all cases by the time it reaches halfway down, a surface swirl has already developed, signifying a tornado is on the ground before condensation connects the surface circulation to the storm. Tornadoes may also occur without wall clouds, under flanking lines, and on the leading edge. Spotters watch all areas of a storm, and the cloud base and surface.[93]
Extremes
Main article: Tornado records



 A map of the tornado paths in the Super Outbreak (April 3–4, 1974)
The most record-breaking tornado in recorded history was the Tri-State Tornado, which roared through parts of Missouri, Illinois, and Indiana on March 18, 1925. It was likely an F5, though tornadoes were not ranked on any scale in that era. It holds records for longest path length (219 miles, 352 km), longest duration (about 3.5 hours), and fastest forward speed for a significant tornado (73 mph, 117 km/h) anywhere on Earth. In addition, it is the deadliest single tornado in United States history (695 dead).[21] The tornado was also the costliest tornado in history at the time (unadjusted for inflation), but in the years since has been surpassed by several others if population changes over time are not considered. When costs are normalized for wealth and inflation, it ranks third today.[94]
The deadliest tornado in world history was the Daultipur-Salturia Tornado in Bangladesh on April 26, 1989, which killed approximately 1,300 people.[68] Bangladesh has had at least 19 tornadoes in its history kill more than 100 people, almost half of the total in the rest of the world.
The most extensive tornado outbreak on record was the April 25–28, 2011 tornado outbreak, which spawned 355 confirmed tornadoes over the southeastern United States - 211 of them within a single 24 hour period. The previous record was the Super Outbreak of 1974 which spawned nearly 148 tornadoes.
While direct measurement of the most violent tornado wind speeds is nearly impossible, since conventional anemometers would be destroyed by the intense winds and flying debris, some tornadoes have been scanned by mobile Doppler radar units, which can provide a good estimate of the tornado's winds. The highest wind speed ever measured in a tornado, which is also the highest wind speed ever recorded on the planet, is 301 ± 20 mph (484 ± 32 km/h) in the F5 Bridge Creek-Moore, Oklahoma, tornado which killed 36 people.[95] Though the reading was taken about 100 feet (30 m) above the ground, this is a testament to the power of the strongest tornadoes.[2]
Storms that produce tornadoes can feature intense updrafts, sometimes exceeding 150 mph (240 km/h). Debris from a tornado can be lofted into the parent storm and carried a very long distance. A tornado which affected Great Bend, Kansas, in November 1915, was an extreme case, where a "rain of debris" occurred 80 miles (130 km) from the town, a sack of flour was found 110 miles (180 km) away, and a cancelled check from the Great Bend bank was found in a field outside of Palmyra, Nebraska, 305 miles (491 km) to the northeast.[96] Waterspouts and tornadoes have been advanced as an explanation for instances of raining fish and other animals.[97]
Safety
Main article: Tornado preparedness
Though tornadoes can strike in an instant, there are precautions and preventative measures that people can take to increase the chances of surviving a tornado. Authorities such as the Storm Prediction Center advise having a pre-determined plan should a tornado warning be issued. When a warning is issued, going to a basement or an interior first-floor room of a sturdy building greatly increases chances of survival.[98] In tornado-prone areas, many buildings have storm cellars on the property. These underground refuges have saved thousands of lives.[99]
Some countries have meteorological agencies which distribute tornado forecasts and increase levels of alert of a possible tornado (such as tornado watches and warnings in the United States and Canada). Weather radios provide an alarm when a severe weather advisory is issued for the local area, though these are mainly available only in the United States. Unless the tornado is far away and highly visible, meteorologists advise that drivers park their vehicles far to the side of the road (so as not to block emergency traffic), and find a sturdy shelter. If no sturdy shelter is nearby, getting low in a ditch is the next best option. Highway overpasses are one of the worst places to take shelter during tornadoes, as the constricted space can be subject to increased wind speed and funneling of debris underneath the overpass.[100]
Myths and misconceptions
Main article: Tornado myths
See also: List of common misconceptions
Folklore often identifies a green sky with tornadoes, and though the phenomenon may be associated with severe weather, there is no evidence linking it specifically with tornadoes.[101] It is often thought that opening windows will lessen the damage caused by the tornado. While there is a large drop in atmospheric pressure inside a strong tornado, it is unlikely that the pressure drop would be enough to cause the house to explode. Some research indicates that opening windows may actually increase the severity of the tornado's damage.[citation needed] A violent tornado can destroy a house whether its windows are open or closed.[102][103]



 The 1999 Salt Lake City tornado disproved several misconceptions, including the idea that tornadoes cannot occur in areas like Utah or in cities.
Another commonly held misconception is that highway overpasses provide adequate shelter from tornadoes. This belief is partly inspired by widely circulated video captured during the 1991 tornado outbreak near Andover, Kansas, where a news crew and several other people take shelter under an overpass on the Kansas Turnpike and safely ride out a tornado as it passes by.[104] However, a highway overpass is a dangerous place during a tornado: the subjects of the video remained safe due to an unlikely combination of events: the storm in question was a weak tornado, did not directly strike the overpass, and the overpass itself was of a unique design.[104] Due to the Venturi effect, tornadic winds are accelerated in the confined space of an overpass.[105] Indeed, in the 1999 Oklahoma tornado outbreak of May 3, 1999, three highway overpasses were directly struck by tornadoes, and at all three locations there was a fatality, along with many life-threatening injuries.[106] By comparison, during the same tornado outbreak, more than 2000 homes were completely destroyed, with another 7000 damaged, and yet only a few dozen people died in their homes.[100]
An old belief is that the southwest corner of a basement provides the most protection during a tornado. The safest place is the side or corner of an underground room opposite the tornado's direction of approach (usually the northeast corner), or the central-most room on the lowest floor. Taking shelter in a basement, under a staircase, or under a sturdy piece of furniture such as a workbench further increases chances of survival.[102][103]
Finally, there are areas which people believe to be protected from tornadoes, whether by being in a city, near a major river, hill, or mountain, or even protected by supernatural forces.[107] Tornadoes have been known to cross major rivers, climb mountains,[108] affect valleys, and have damaged several city centers. As a general rule, no area is safe from tornadoes, though some areas are more susceptible than others.[23][102][103]
Ongoing research



 A Doppler on Wheels unit observing a tornado near Attica, Kansas
Meteorology is a relatively young science and the study of tornadoes is newer still. Although researched for about 140 years and intensively for around 60 years, there are still aspects of tornadoes which remain a mystery.[109] Scientists have a fairly good understanding of the development of thunderstorms and mesocyclones,[110][111] and the meteorological conditions conducive to their formation. However, the step from supercell (or other respective formative processes) to tornadogenesis and predicting tornadic vs. non-tornadic mesocyclones is not yet well known and is the focus of much research.[71]
Also under study are the low-level mesocyclone and the stretching of low-level vorticity which tightens into a tornado,[71] namely, what are the processes and what is the relationship of the environment and the convective storm. Intense tornadoes have been observed forming simultaneously with a mesocyclone aloft (rather than succeeding mesocyclogenesis) and some intense tornadoes have occurred without a mid-level mesocyclone.[112]
In particular, the role of downdrafts, particularly the rear-flank downdraft, and the role of baroclinic boundaries, are intense areas of study.[113]
Reliably predicting tornado intensity and longevity remains a problem, as do details affecting characteristics of a tornado during its life cycle and tornadolysis. Other rich areas of research are tornadoes associated with mesovortices within linear thunderstorm structures and within tropical cyclones.[114]
Scientists still do not know the exact mechanisms by which most tornadoes form, and occasional tornadoes still strike without a tornado warning being issued.[115] Analysis of observations including both stationary and mobile (surface and aerial) in-situ and remote sensing (passive and active) instruments generates new ideas and refines existing notions. Numerical modeling also provides new insights as observations and new discoveries are integrated into our physical understanding and then tested in computer simulations which validate new notions as well as produce entirely new theoretical findings, many of which are otherwise unattainable. Importantly, development of new observation technologies and installation of finer spatial and temporal resolution observation networks have aided increased understanding and better predictions.[116]
Research programs, including field projects such as the VORTEX projects (Verification of the Origins of Rotation in Tornadoes Experiment), deployment of TOTO (the TOtable Tornado Observatory), Doppler On Wheels (DOW), and dozens of other programs, hope to solve many questions that still plague meteorologists.[43] Universities, government agencies such as the National Severe Storms Laboratory, private-sector meteorologists, and the National Center for Atmospheric Research are some of the organizations very active in research; with various sources of funding, both private and public, a chief entity being the National Science Foundation.[91][117] The pace of research is partly constrained by the number of observations that can be taken; gaps in information about the wind, pressure, and moisture content throughout the local atmosphere; and the computing power available for simulation.[118]
Solar storms similar to tornadoes have been recorded, but it is unknown how closely related they are to their terrestrial counterparts.[119]
Gallery




A tornado that occurred at Seymour, Texas in April 1979




F4 Tornado in Roanoke, Illinois on July 13, 2004




The mature stage of a tornado that occurred in Union City, Oklahoma on May 24, 1973




A radar image of a violently tornadic classic supercell near Oklahoma City, Oklahoma on May 3, 1999




F5 Tornado approaching Elie, Manitoba on June 22, 2007




A tornado south of Anadarko, Oklahoma on May 3, 1999 during the 1999 Oklahoma tornado outbreak




A rare F0 Tornado in its final stages over the North Sea near Vrångö, Sweden on July 17, 2011

See also

Portal icon Weather portal
Cultural significance of tornadoes
Cyclone
Derecho
History of tropical cyclone-spawned tornadoes
Hurricane
List of tornadoes and tornado outbreaks
Secondary flow
Skipping tornado
Tornado drill
Tornadoes of 2014
Typhoon
Whirlwind
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Further reading
Howard B. Bluestein (1999). Tornado Alley: Monster Storms of the Great Plains. New York: Oxford University Press. ISBN 0-19-510552-4.
Marlene Bradford (2001). Scanning the Skies: A History of Tornado Forecasting. Norman, OK: University of Oklahoma Press. ISBN 0-8061-3302-3.
Thomas P. Grazulis (January 1997). Significant Tornadoes Update, 1992–1995. St. Johnsbury, VT: Environmental Films. ISBN 1-879362-04-X.
External links
Find more about tornado at Wikipedia's sister projects
 Definitions and translations from Wiktionary
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NOAA Storm Database 1950–Present[dead link]
European Severe Weather Database
Social & Economic Costs of Tornadoes
Tornado Detection and Warnings
Electronic Journal of Severe Storms Meteorology
NOAA Tornado Preparedness Guide
Tornado History Project - Maps and statistics from 1950-Present
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