Severe thunderstorm warning
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The examples and perspective in this article may not represent a worldwide view of the subject. (December 2010) |
A severe thunderstorm warning (SAME code: SVR) is issued when trained storm spotters or a Doppler weather radar indicate a strong thunderstorm is producing dangerously large hail or high winds, capable of causing significant damage.[1] In the United States, it does not account for lightning, a significant hazard in any thunderstorm, or flooding caused by a severe thunderstorm's extreme rainfall. (a Flood advisory or Flash flood warning is issued in this case).[1] A similar warning is issued by Environment Canada's Meteorological Service of Canada from their offices in Vancouver, Edmonton, Toronto, Montreal and Dartmouth.[2] Skywarn issues the warnings for the United Kingdom.[3]
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[edit] Definition
In the U.S., the National Weather Service defines a severe thunderstorm as having large hail of at least 1 inch (2.5 cm), severe (storm-force) winds of 58 miles per hour (93 km/h) or greater, 1 or more tornadoes (though this would result in a tornado warning), or any combination of the three.[4] Prior to January 2010, the size in which hail in a severe thunderstorm would be considered severe was ¾ of an inch; public complacency due to overly frequent issuances of severe thunderstorm warnings and recent studies stating that hail does not produce damage until it reaches one inch in diameter caused the upgrade.[5] In Canada, a severe thunderstorm has wind gusts of >90 km/h (56 mph), hail with a diameter of >20 mm (0.8 inch), rainfall of >50 mm (2 inches) in an hour or >75 mm (3 inches) in three hours, or tornadoes.[2]
A severe thunderstorm warning means there is significant danger for the warned area. Occasionally, severe thunderstorms can and do produce a tornado without warning.[6] While not all severe thunderstorms produce tornadoes, they can produce serious straight line wind damage as severe as a tornado (and can actually cover a much wider area than a tornado).[7] If a tornado is detected on radar or sighted, a tornado warning will be issued either in replacement of or concurrently to the existing severe thunderstorm warning.[8] Generally, but not always, a severe thunderstorm watch or tornado watch will precede a warning.
If a Tornado Warning is issued, based on Doppler weather radar, it means strong rotation has been detected. Usually if a severe thunderstorm is producing weak rotation, it will only be a Severe Thunderstorm Warning; however, the public will usually be advised that this rotation has been detected, and the storm should be watched closely.
In the United States, local National Weather Service forecast offices, particularly those in the Great Plains or Southeastern U.S., sometimes include the wording "Severe thunderstorms can produce tornadoes with no advance warning..." or a similar reference in their severe thunderstorm warning products, usually when there is a tornado threat or especially when a tornado watch is in effect, though sometimes the wording is included even if the threat of severe weather does not include a threat of tornadic activity.
Some storms, especially in the Great Plains, may produce massive hailstones the size of baseballs (2.75 inches (7.0 cm)) or larger, falling fast enough to potentially kill a person by repeated blunt trauma.
In the United States, the National Weather Service issues warnings for tornadoes and severe thunderstorms in polygon shapes. Warnings are usually delineated in text by county or by a section of a county.
[edit] Criteria in various countries
| Country | Tornado | Minimum hail size | Minimum wind speed | Minimum rainfall rate per hour | Source |
|---|---|---|---|---|---|
| United States | See Tornado warning | 1 inch (25 mm) | 58 miles per hour (93 km/h) | See Flash flood warning | [1] |
| Canada | See Tornado warning | 20 millimetres (0.79 in) | 90 kilometres per hour (56 mph) | 50 millimetres (2.0 in) | [2] |
| Australia | All | 20 millimetres (0.79 in) | 90 kilometres per hour (56 mph) | "Conducive to flash flooding" | [9] |
| New Zealand | F1 or stronger | 20 millimetres (0.79 in) | 110 kilometres per hour (68 mph) | 25 millimetres (0.98 in) | [10] |
| Germany | All | 15 millimetres (0.59 in) | 105 kilometres per hour (65 mph) | 20 millimetres (0.79 in) | [11] |
| Mexico | All | 5 millimetres (0.20 in) | 89 kilometres per hour (55 mph) | 20 millimetres (0.79 in) | [12][13][14] |
| United Kingdom | All | 20 millimetres (0.79 in) | 55 miles per hour (89 km/h) | "Conducive to flash flooding" | [3] |
[edit] Examples of a Severe Thunderstorm Warning
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An example of a severe thunderstorm warning, this one being issued in Minnesota
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Examples of a Severe Thunderstorm Warnings issued by the National Weather Service in the United States.[15]
WUUS53 KICT 020245
SVRICT
KSC053-105-169-020345-
/O.NEW.KICT.SV.W.0171.110602T0245Z-110602T0345Z/
BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE WICHITA KS
945 PM CDT WED JUN 1 2011
THE NATIONAL WEATHER SERVICE IN WICHITA HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR...
EASTERN ELLSWORTH COUNTY IN CENTRAL KANSAS...
SOUTHEASTERN LINCOLN COUNTY IN CENTRAL KANSAS...
SALINE COUNTY IN CENTRAL KANSAS...
* UNTIL 1045 PM CDT
* AT 941 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND EXTREME DAMAGING WINDS IN EXCESS OF 100 MPH. THIS STORM
WAS LOCATED NEAR WESTFALL...OR 12 MILES SOUTHEAST OF LINCOLN...AND
MOVING SOUTHEAST AT 35 MPH.
* LOCATIONS IMPACTED INCLUDE...
SALINA...BROOKVILLE...KANOPOLIS STATE PARK...NEW CAMBRIA...
SMOLAN...GLENDALE AND SALINA AIRPORT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
THIS IS AN EXTREMELY DANGEROUS SITUATION WITH TORNADO LIKE WIND
SPEEDS EXPECTED. MOBILE HOMES AND HIGH PROFILE VEHICLES ARE
ESPECIALLY SUSCEPTIBLE TO WINDS OF THIS MAGNITUDE AND MAY BE
OVERTURNED. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE
LOWEST FLOOR OF YOUR HOME OR BUSINESS. THIS STORM HAS THE POTENTIAL
TO CAUSE SERIOUS INJURY AND SIGNIFICANT DAMAGE TO PROPERTY.
&&
A TORNADO WATCH REMAINS IN EFFECT UNTIL MIDNIGHT CDT THURSDAY MORNING
FOR EAST CENTRAL KANSAS.
LAT...LON 3908 9792 3896 9792 3896 9737 3880 9737
3858 9805 3892 9833 3910 9803
TIME...MOT...LOC 0246Z 322DEG 31KT 3885 9802
WIND...HAIL 100MPH 1.00IN
$$
MCGUIRE
SEVERE THUNDERSTORM WARNING NEC037-039-119-141-167-302230- /O.NEW.KOAX.SV.W.0024.120330T2144Z-120330T2230Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA 444 PM CDT FRI MAR 30 2012 THE NATIONAL WEATHER SERVICE IN OMAHA HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... COLFAX COUNTY IN EAST CENTRAL NEBRASKA... EXTREME SOUTHWESTERN CUMING COUNTY IN EASTERN NEBRASKA... EXTREME SOUTHEASTERN MADISON COUNTY IN EASTERN NEBRASKA... NORTHEASTERN PLATTE COUNTY IN EAST CENTRAL NEBRASKA... EXTREME SOUTHWESTERN STANTON COUNTY IN EASTERN NEBRASKA... * UNTIL 530 PM CDT * AT 441 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A SEVERE THUNDERSTORM PRODUCING QUARTER SIZE HAIL. THIS STORM WAS LOCATED NEAR CRESTON...OR 19 MILES NORTH OF COLUMBUS...AND MOVING EAST AT 30 MPH. * LOCATIONS IMPACTED INCLUDE... CLARKSON...HOWELLS...LEIGH...CRESTON AND HUMPHREY. PRECAUTIONARY/PREPAREDNESS ACTIONS... SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS IN EXCESS OF 60 MPH... DESTRUCTIVE HAIL...DEADLY LIGHTNING AND VERY HEAVY RAIN. FOR YOUR PROTECTION...MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE ROAD. && LAT...LON 4179 9748 4173 9691 4145 9702 4163 9753 TIME...MOT...LOC 2141Z 285DEG 24KT 4171 9743 WIND...HAIL <50MPH 1.00IN $$ KERN
[edit] See also
[edit] References
- ^ a b c "Severe Thunderstorm Warning". NOAA National Weather Service Glossary. http://www.nws.noaa.gov/glossary/index.php?word=Severe+Thunderstorm+Warning. Retrieved 2010-01-10.
- ^ a b c Environment Canada. "Severe Thunderstorm Warning". Prairie and Northern Region Weather Watch and Weather Warning Criteria. http://www.pnr-rpn.ec.gc.ca/air/severewthr/warning.en.html. Retrieved 2010-01-10.
- ^ a b "SkyWarn UK Warning criteria". SkyWarn UK. http://beta.skywarn.org.uk/criteria.html. Retrieved 21 December 2011.
- ^ http://www.crh.noaa.gov/dvn/?n=oneinchhail
- ^ McClure, Mike (2009-05-26). "New One Inch Hail Criteria for Severe Thunderstorm Warnings". Weather Home Companion. National Weather Service Quad Cities, IA/IL. http://www.webcitation.org/5uzxK9Etn. Retrieved 2010-12-15.
- ^ Howerton, Paul (2008-06-12). "Severe Thunderstorm Warning". Iowa Environmental Mesonet NWS Product Archive. http://mesonet.agron.iastate.edu/vtec/#2008-O-NEW-KICT-SV-W-0294. Retrieved 2010-01-10.
- ^ "Severe Thunderstorm". NOAA National Weather Service Glossary. http://www.nws.noaa.gov/glossary/index.php?word=Severe+thunderstorm. Retrieved 2010-01-10.
- ^ Howerton, Paul (2008-06-12). "Severe Thunderstorm Warning". Iowa Environmental Mesonet NWS Product Archive. http://mesonet.agron.iastate.edu/vtec/#2008-O-NEW-KICT-TO-W-0049. Retrieved 2010-01-10.
- ^ Bureau of Meteorology (2004-10). "Bureau of Meteorology: Severe Weather Warning Education". Severe Weather Warning Education. http://reg.bom.gov.au/catalogue/warnings/WarningsInformation_SW_Ed.shtml. Retrieved 2010-02-06.
- ^ Meteorological Service of New Zealand Ltd.. "Severe Thunderstorm Warnings and other NZ Weather Warnings from MetService.com". Severe Thunderstorm Criteria. http://www.metservice.com/national/warnings/severe-thunderstorm-warnings. Retrieved 2010-02-06.
- ^ Deutscher Wetterdienst. "Wetter und Klima - Deutscher Wetterdienst -- Warnungen" (in German). Unwetterkriterien. http://www.dwd.de/bvbw/appmanager/bvbw/dwdwwwDesktop?_nfpb=true&_pageLabel=_dwdwww_wetter_warnungen_warnungen&T169600781711254206874155gsbDocumentPath=Navigation%2FOeffentlichkeit%2FWetter__Warnungen%2FWarnungen%2FAmtliche__Warnungen%2FKriterien__Unwetterkriterien__node.html__nnn%3Dtrue. Retrieved 2010-02-06.
- ^ Servicio Meteorológico Nacional (2010-01-30). "Granizo" (in Spanish). Servicio Meteorologico Nacional - Mexico - Glosario G. http://smn.conagua.gob.mx/glosario/glos-g.html. Retrieved 2010-02-06.
- ^ Servicio Meteorológico Nacional (2010-02-05). "Escalas empleadas" (in Spanish). http://smn.conagua.gob.mx/boletin/avisos/nortes/nortes.html. Retrieved 2010-02-06.
- ^ Servicio Meteorológico Nacional (2010-02-05). "Aviso de Tormentas Intensas y Granizo" (in Spanish). http://smn.conagua.gob.mx/boletin/avisos/tormentas/tormenta.html. Retrieved 2010-02-06.
- ^ McGuire, Mick (2011-06-02). "NWS Wichita 2011 Severe Thunderstorm Warning #171". National Weather Service Wichita, KS. http://mesonet.agron.iastate.edu/vtec/#2011-O-NEW-KICT-SV-W-0171. Retrieved 2012-02-03.
[edit] External links
- Bureau of Meteorology: Severe Thunderstorm Warnings
- Meteorological Service of Canada
- United States National Weather Service
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