Severe thunderstorm warning

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Severe thunderstorm with a clear slot near main updraft core. Typically a tornado, if present, will form in this area. Severe thunderstorm - NOAA.jpg
Severe thunderstorm with a clear slot near main updraft core. Typically a tornado, if present, will form in this area.
Clouds from a dissipating severe thunderstorm. December312020SevereThunderstorm.jpg
Clouds from a dissipating severe thunderstorm.

A severe thunderstorm warning (SAME code: SVR) is a type of public warning for severe weather that is issued by weather forecasting agencies worldwide when one or more severe thunderstorms have been detected by Doppler weather radar, observed by weather spotters, or reported by an emergency management agency, law enforcement, or the general public. Unlike a watch, a warning is issued to areas in the direct path of active severe thunderstorms, that are expecting a direct impact typically within an hour. Severe thunderstorms can cause property damage and injury due to large hail, high winds, and flooding due to torrential rainfall. The exact criteria to issue a warning varies from country to country.

Contents

In the United States, the National Weather Service issues a warning when an observed thunderstorm is producing wind gusts of at least 58 miles per hour (93 km/h), or hail of at least 1 inch (2.5 cm) in diameter. Most forecasting agencies have similar criteria, but some agencies, such as Environment Canada, also include high rainfall rate. Others may instead issue a flood advisory or in the case of the National Weather Service, a flash flood warning. [1]

Definition

A severe thunderstorm warning indicates the warned area is in impending danger from hail or wind speeds meeting warning criteria as well as from lightning and hydrological impacts associated with the storm cell. Severe thunderstorms can and occasionally do produce tornadoes without warning. [2] While not all severe thunderstorms produce tornadoes, they can produce serious straight line wind damage as severe as a lower-category tornado or hurricane, and can actually cover a much wider area than that exceeded by a tornado's comparatively narrow path width. [3]

If a tornado is detected on radar or is sighted visually, a tornado warning will be issued either in replacement of or concurrently to the existing severe thunderstorm warning. [4] Generally, but not always, a severe thunderstorm watch or tornado watch (or a regional equivalent thereof) will precede a warning. If a tornado warning is issued, based on Doppler weather radar, it means strong rotation has been detected within a thunderstorm. Usually, if a thunderstorm is producing only weak rotation, it will only yield hazardous weather warranting a severe thunderstorm warning. However, the public will usually be advised this type of rotation has been detected and that the storm in question should be watched closely in the near future for further intensification.

Regional basis and criteria

United States

In the United States, the National Weather Service (NWS) defines a severe thunderstorm as having large hail of one inch (2.5 cm) in diameter or larger, surface wind speeds of 58 mph (50 kn; 93 km/h) or greater, and/or a tornado. [5] [6] Prior to January 2010, the hail size for which a thunderstorm would be considered severe was 0.75 inches (1.9 cm); public complacency due to overly frequent issuances of severe thunderstorm warnings and recent studies stating hail did not produce significant damage on the ground until it reached one inch in diameter caused the upgrade in hail criteria. [7] Severe thunderstorm warnings are issued by the National Weather Service through the agency's local Weather Forecast Offices, which utilize WarnGen software integrated into the Advance Weather Interactive Processing System (AWIPS) to generate the warning statement; it is then disseminated through various communication routes accessed by the media and various agencies, on the internet, to NOAA satellites, over NOAA Weather Radio and, depending on the storm's severity and at the office's discretion, via activation of the Emergency Alert System to local broadcast media and Wireless Emergency Alerts for cellular phones.

Local NWS forecast offices outline warnings for tornadoes and severe thunderstorms in polygonal shapes for map-based weather hazard products distributed to the main agency, individual forecast office websites and the Storm Prediction Center (including open-source APIs available for free use to public weather websites and mobile apps), based on the storm's projected path as determined by Doppler weather radar at the time of the warning's issuance. In NWS text products, warnings are usually illustrated by individual counties, parishes or other county-equivalent jurisdictions (sections or the entirety thereof, and in list format if it covers more than one jurisdiction), particularly dependent on the jurisdiction's total land area. Prior to October 2007, warnings were issued by the National Weather Service on a per-county basis. [8] SPC and NWS products, as well as severe weather alert displays used by some television stations, typically highlight severe thunderstorm warnings with a yellow or orange polygon or filled county/parish/equivalent jurisdiction outline.

The NWS has the option of adding enhanced wording to severe thunderstorm warnings and update statements issued as a Severe Weather Statement (SVS)—"particularly dangerous situation" (PDS), "severe thunderstorm emergency", or, as used by some Central and Southern Region offices as indicative PDS wording, "this is a very dangerous storm"—when an extremely intense severe thunderstorm expected to impact a densely populated area contains very large hailstones and/or intense straight-line winds capable of causing major structural damage (especially to roofs, windows, siding and structures of poor construction such as outbuildings and mobile homes), and severe injury if not death to people and animals exposed outdoors (from either repeated hail-induced blunt trauma or wind-generated debris). Although it is an unofficial alert product, a "severe thunderstorm emergency" statement—an extension of the tornado emergency statements issued to warn of a violent tornado impacting populated areas—is the highest and most urgent level relating to non-tornadic severe thunderstorms. When a threat of tornadic activity exists (especially if a tornado watch is in effect), local NWS forecast offices, particularly those in the Great Plains or Southeastern U.S., will sometimes include a safety precaution action statement indicating "Severe thunderstorms can produce tornadoes with no advance warning..." or similar wording in their severe thunderstorm warnings to advise the public to keep abreast of possible tornado development and any tornado warnings that may be issued.

As part of the agency’s March 2012 implementation of a multi-tier Impact Based Warning (IBW) system to notify the public and emergency management officials of the severity of specific severe weather phenomena, National Weather Service-issued severe thunderstorm warnings and associated Severe Weather Statements providing updated storm information include event tags at the bottom of the product text providing summarical estimates of straight-line wind speeds (sustained or gusts) and hail size and, when applicable, an indication of possible tornadic development. The product text will also provide a summary of impacts to life and property that may be caused by the hailstones and winds being produced by the parent thunderstorm. Initially implemented at six NWS offices in Kansas and Missouri, the categorical threat and damage indicator text—which are applicable to all of the agency’s Weather Forecast Offices, primarily those operating within the agency's Central and Southern Region divisions—were expanded to 33 additional Central Region WFOs in March 2013; eight additional offices operating within the Eastern, Southern and Western Region divisions began using the IBW indicators in March 2014. The entire agency began using the format in 2016. The threat indicators consist of three coded taglines, ascending by observational level: [9] [10]

  • Tornado – indicates the mesocyclone of the parent severe thunderstorm is producing circulation at or near the cloud base, which may warrant the issuance of a tornado warning if base-level rotation strengthens. [11] When incorporated into the storm impact summary, the tornado tag (appearing in applicable severe thunderstorm warning products as “TORNADO...POSSIBLE”) will precede the wind and hail tags.
  • Hail – indicates the estimated size of hail (measured in inches) being produced by the parent severe thunderstorm (e.g., “HAIL...1.25IN”). When included, the “Impact” section of the warning text will describe potential damage impacts from the hailstones, with the impact message varying in severity depending on radar estimated or observed reports of measured large hail (e.g., “Hail damage to vehicles is expected.”) and the “Hazard” section will provide a comparison of the size of hailstones to objects of similar size (e.g., “baseball size hail” for hailstones measuring 2.75"). (If the tag lists either “HAIL...0.00IN”, indicating no hail is accompanying the storm, or “HAIL...<.75IN”, indicating hailstones below severe criteria that may range in equivalent size from peas [.25"] to pennies [.75"], no hail size will be indicated in the “Hazard” row nor will a description of damage risk be included in the “Impact” section.)
  • Wind – indicates estimated speed (in miles per hour) of wind gusts produced by the parent thunderstorm (e.g., “WIND...70MPH”). When included, the “Impact” section of the warning text will describe potential damage impacts from the straight-line winds, varying in severity depending on wind strength (e.g., “Expect considerable tree damage. Wind damage is also likely to mobile homes, roofs, and outbuildings.”).

Since July 28, 2021 (or as late as August 2 in certain County Warning Areas), the NWS has incorporated categorical damage threat indicators for higher-end hail and/or wind events at the bottom of text products for severe thunderstorm warnings (including update statements to existing warnings issued as Severe Weather Statements): [12] [13]

  • Considerable – to be used when hail of 1.75 inches (4.4 cm) or larger and/or winds at or above 70 miles per hour (110 km/h) is indicated by radar or observed.
  • Destructive – to be used when hail of 2.75 inches (7.0 cm) or larger and/or winds at or above 80 miles per hour (130 km/h) is indicated by radar or observed. (Warnings assigned this indicator incorporate the notation "THIS IS A DESTRUCTIVE STORM FOR[...]"—which superseded the boilerplate "this is a particularly dangerous situation" wording—between the storm summary and hazard information in the product text to indicate certain areas under greatest threat from the specified wind speeds and/or hail size.)

Similar to the indicators used for tornado warnings since the 2013 implementation of its Impact Based Warning system, the categorical criteria—which will be applicable to all NWS Weather Forecast Offices—was introduced to further explain to the public of the dangers of some thunderstorms, especially those that occur in the Great Plains, that can produce massive hailstones of baseball size (2.75 inches [7.0 cm]) or larger that may fall fast enough to severely injure if not kill a person by repeated blunt trauma, and winds that can cause damage equivalent to hurricanes and tornadoes (especially to roofs and weaker structures such as outbuildings and mobile homes). When deemed necessary, initial warnings and Severe Weather Statement updates containing the "destructive" tag will be disseminated into the Wireless Emergency Alerts system as well. [13]

Canada

In Canada, a severe thunderstorm is defined as having wind gusts of greater than 90 km/h (56 mph), hail with a diameter of greater than two centimetres (0.79 in), rainfall rates of greater than 50 millimetres (2.0 in) in one hour or greater than 75 millimetres (3.0 in) in three hours, or tornadoes. [14] Environment and Climate Change Canada issues severe thunderstorm warnings through regional offices of the Meteorological Service of Canada based in Vancouver, Edmonton, Winnipeg, Toronto, Montreal and Dartmouth for specified municipalities and census subdivisions, sometimes including areas adjacent to a particular warned thunderstorm that are not in the immediate approximate path but may experience severe weather from adjacent thunderstorms during the warning timeframe. [14] Warnings are disseminated to the public through broadcast and online media outlets, and Weatheradio Canada; depending on storm severity and regional office discretion, the warning may require activation of the National Public Alerting System (Alert Ready) (French : Système national d'alertes à la population [En Alerte]) and feeding provincial alerting systems (such as Alberta Emergency Alert and SaskAlert) to distribute the alert to local broadcast media and cellular phones.

United Kingdom

In United Kingdom, a severe thunderstorm is defined as having hail in excess of two centimetres (0.79 in) and straight-line winds in excess of 89 km/h (48 kn; 55 mph). The Met Office issues de facto severe thunderstorm warnings through general-purpose weather warning products disseminated by the National Severe Weather Warning Service (classified as yellow, amber or red, depending on storm severity and proximity to the time of expected onset of storm impacts). [15]

Australia

In Australia, a severe thunderstorm is defined as having damaging winds in excess of 90 km/h (49 kn; 56 mph), large hail of two centimetres (0.79 in) or larger, heavy rainfall, and flash flooding. Severe thunderstorm warnings are issued by regional offices of the Bureau of Meteorology (BOM) based in Melbourne Docklands, Adelaide, Darwin, Perth and Brisbane. [16] BOM-issued severe thunderstorm warnings are outlined as either a broad-based warning, covering expected impacts within a weather reporting area, or as a detailed warning, when a thunderstorm is within weather-watch radar range and includes a map depicting any existing thunderstorms and the forecast direction of movement for up to 60 minutes. [16] [17]

New Zealand

In New Zealand, a severe thunderstorm is defined by the Meteorological Service of New Zealand (MetService) (Māori : Te Ratonga Tirorangi) as having large hail of 20 millimetres (2.0 cm; 0.79 in), damaging winds of 110 km/h (59 kn; 68 mph), rainfall rates of at least 25 millimetres (0.98 in) per hour and/or tornadoes producing winds above 116 km/h (63 kn; 72 mph) (rated F1 or stronger on the Fujita Scale). [18] MetService issues severe thunderstorm warnings to alert regions expected to experience severe weather phenomena meeting regional criteria and utilize the Common Alerting Protocol (CAP) to generate the warning statement. [19] The warning is then disseminated to the public through terrestrial television and radio stations, online media, mobile app and SMS messaging through Emergency Mobile Alert (EMA); if a tornado has been sighted or indicated by radar within the warned area during the severe thunderstorm warning's duration, civil defense sirens, if present, are usually activated within the region to be affected to inform people who are present outdoors of the approaching tornado threat. [19]

Philippines

In the Philippines, a severe thunderstorm is defined by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) as having strong winds, large hail, torrential rainfall, tornadoes, flash flooding and/or landslides. PAGASA, through its regional services divisions, issue thunderstorm advisories to alert regions and/or provinces expected to experience severe weather phenomena meeting regional criteria within a period of two hours. [20] Warnings are disseminated to the public through terrestrial television and radio outlets, [21] online media, and via SMS messages through the National Disaster Risk Reduction and Management Council's Emergency Cell Broadcast System. [20]

Criteria in various countries

CountryTornadoMinimum hail sizeMinimum wind speedMinimum rainfall rate per hourSource
United StatesSee Tornado Warning 1 inch (25 mm)58 miles per hour (93 km/h)See Flash Flood Warning [6]
CanadaSee Tornado Warning 20 millimetres (0.79 in)90 kilometres per hour (56 mph)50 millimetres (2.0 in) [14]
AustraliaAll20 millimetres (0.79 in)90 kilometres per hour (56 mph)"Conducive to flash flooding" [22]
New Zealand F1 or stronger20 millimetres (0.79 in)110 kilometres per hour (68 mph)25 millimetres (0.98 in) [23]
GermanyAll15 millimetres (0.59 in)105 kilometres per hour (65 mph)20 millimetres (0.79 in) [24]
MexicoAll5 millimetres (0.20 in)89 kilometres per hour (55 mph)20 millimetres (0.79 in) [25] [26] [27]
United KingdomAll20 millimetres (0.79 in)55 miles per hour (89 km/h)"Conducive to flash flooding" [15]

Examples of severe thunderstorm warnings

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Severe Thunderstorm Warning for Northern Minnesota using the Old Tom Voice
An example of a severe thunderstorm warning using the old Console Replacement System (CRS) Tom Voice, this one being issued in Northern Minnesota
Problems playing this file? See media help.
Gnome-mime-sound-openclipart.svg
Severe Thunderstorm Warning for Southern Wisconsin using the New Paul Voice
An example of a severe thunderstorm warning using the new Broadcast Message Handler (BMH) Paul Voice, this one being issued in Marathon, WI, and Portage, WI, on August 1, 2024 at 4:22 PM CST; and being aired on WSPT.
Problems playing this file? See media help.

Here is an example of a Severe Thunderstorm Warning issued by the National Weather Service in San Angelo, Texas.

Severe Thunderstorm Warning VAC059-153-600-683-685-140130- /O.NEW.KLWX.SV.W.0529.190814T0058Z-190814T0130Z/ Severe Thunderstorm Warning TXC151-253-042245- /O.NEW.KSJT.SV.W.0017.220404T2223Z-220404T2245Zny  BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service San Angelo TX 523 PM CDT Mon Apr 4 2022  The National Weather Service in San Angelo has issued a  * Severe Thunderstorm Warning for...   Western Jones County in west central Texas...   East central Fisher County in west central Texas...  * Until 545 PM CDT.  * At 521 PM CDT, a severe thunderstorm was located near Neinda,   moving east at 40 mph.    HAZARD...60 mph wind gusts and quarter size hail.    SOURCE...Radar indicated.    IMPACT...Hail damage to vehicles is expected. Expect wind damage            to roofs, siding, and trees.  * This severe thunderstorm will be near...   Neinda around 525 PM CDT.   Anson around 540 PM CDT.  Other locations impacted by this severe thunderstorm include Truby and The Intersection Of Us-180 And Ranch Road 126.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  For your protection move to an interior room on the lowest floor of a building.  To report severe weather, contact your nearest law enforcement agency. They will send your report to the National Weather Service office in San Angelo.  Large hail and damaging winds and continuous cloud to ground lightning is occurring with this storm. Move indoors immediately. Lightning is one of nature`s leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning.  Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways.  &&  LAT...LON 3261 10025 3276 10031 3294 9990 3263 9981 TIME...MOT...LOC 2221Z 258DEG 33KT 3271 10012  HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...1.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH  $$  TP

This is a Severe Thunderstorm Warning issued for a cluster of severe thunderstorms.

Severe Thunderstorm Warning ALC003-FLC033-113-130200- /O.NEW.KMOB.SV.W.0225.200713T0114Z-200713T0200Z/  BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Mobile AL 814 PM CDT Sun Jul 12 2020  The National Weather Service in Mobile has issued a  * Severe Thunderstorm Warning for...   Southeastern Baldwin County in southwestern Alabama...   West central Santa Rosa County in northwestern Florida...   Escambia County in northwestern Florida...  * Until 900 PM CDT.  * At 813 PM CDT, a cluster of severe thunderstorms was located near   Bay Minette, moving southeast at 35 mph.    HAZARD...60 mph wind gusts.    SOURCE...Radar indicated.    IMPACT...Expect damage to roofs, siding, and trees.  * Locations impacted include...   Ensley, Gonzalez, Bay Minette, Pace, Lillian, Molino and Perdido   Beach.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  For your protection move to an interior room on the lowest floor of a building.  Damaging winds and continuous cloud to ground lightning is occurring with this storm. Move indoors immediately. Lightning is one of nature's leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning.  Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways.  &&  LAT...LON 3022 8750 3092 8781 3099 8770 3070 8706 TIME...MOT...LOC 0113Z 301DEG 31KT 3084 8779  HAIL...<.75IN WIND...60MPH  $$  CGAL

This is a Severe Thunderstorm Warning for winds associated with a strong outflow boundary, as opposed to a traditional thunderstorm. [28] 

287  WUUS53 KLOT 162204 SVRLOT ILC031-043-063-093-097-111-197-162245- /O.NEW.KLOT.SV.W.0073.240616T2204Z-240616T2245Z/  BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Chicago/Romeoville 504 PM CDT Sun Jun 16 2024  The National Weather Service in Chicago has issued a  * Severe Thunderstorm Warning for...   Southeastern Kendall County in northeastern Illinois...   Lake County in northeastern Illinois...   Will County in northeastern Illinois...   Northeastern Grundy County in northeastern Illinois...   Northeastern McHenry County in northeastern Illinois...   DuPage County in northeastern Illinois...   Cook County in northeastern Illinois...  * Until 545 PM CDT.  * At 502 PM CDT, severe outflow winds from thunderstorms were    located along a line extending from Channel Lake to Elk Grove    Village to near Romeoville to near Morris, moving east at 35 mph.    This strong surge of outflow winds from weakening thunderstorms    will produce wind gusts of 50 to locally 60 mph, strong enough to    down some trees and powerlines. These strong winds will be    accompanied by little or no rain.    HAZARD...60 mph wind gusts.    SOURCE...Radar indicated.    IMPACT...Expect damage to roofs, siding, and trees.  * Severe thunderstorms will be near...   Chicago, Joliet, Waukegan, Arlington Heights, Bolingbrook, Des    Plaines, Mount Prospect, Downers Grove, Glenview, and Elmhurst    around 510 PM CDT.   Skokie, Orland Park, Berwyn, Oak Park, Austin, Highland Park,    Wilmette, Zion, Brookfield, and Justice around 515 PM CDT.   Cicero, Evanston, Oak Lawn, Irving Park, West Ridge, Burbank,    Mokena, Palos Hills, Logan Square, and Humboldt Park around 520 PM    CDT.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  For your protection move to an interior room on the lowest floor of a building.  Wind damage with these storms will occur before any rain or lightning. Do not wait for the sound of thunder before taking cover. SEEK SHELTER IMMEDIATELY inside a sturdy structure and stay away from windows.  &&  LAT...LON 4249 8780 4227 8783 4213 8774 4206 8767       4190 8761 4190 8760 4188 8762 4185 8761       4178 8756 4173 8757 4129 8793 4129 8801       4128 8802 4128 8847 4160 8822 4199 8809       4250 8825 TIME...MOT...LOC 2202Z 258DEG 32KT 4247 8815 4201 8801 4162 8813 4136 8833  HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH  $$  Izzi

This is a Severe Thunderstorm Warning with a "considerable" tag to denote that 70 mph wind gusts were possible.

� 664 WUUS53 KLBF 052239 SVRLBF NEC017-031-052300- /O.NEW.KLBF.SV.W.0108.210805T2239Z-210805T2300Z/  BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service North Platte NE 539 PM CDT Thu Aug 5 2021  The National Weather Service in North Platte has issued a  * Severe Thunderstorm Warning for...   East central Cherry County in north central Nebraska...   Southwestern Brown County in north central Nebraska...  * Until 600 PM CDT.  * At 539 PM CDT, a severe thunderstorm was located 12 miles southwest   of Johnstown, or 18 miles southwest of Ainsworth, moving southeast   at 30 mph.    HAZARD...70 mph wind gusts and quarter size hail.    SOURCE...Radar indicated.    IMPACT...Hail damage to vehicles is expected. Expect considerable            tree damage. Wind damage is also likely to mobile homes,            roofs, and outbuildings.  * Locations impacted include...   Moon Lake, Willow Lake State Wildlife Management Area and Long Lake   State Wildlife Management Area.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  For your protection move to an interior room on the lowest floor of a building.  &&  LAT...LON 4244 10033 4249 10019 4227 9991 4219 10022 TIME...MOT...LOC 2239Z 327DEG 26KT 4242 10018  THUNDERSTORM DAMAGE THREAT...CONSIDERABLE HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...1.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...70 MPH  $$  Sporer


This is a Severe Thunderstorm Warning with "destructive" wording to denote that three-inch hail was possible with this storm, with a request for activation of Wireless Emergency Alerts (as indicated by the wording "BULLETIN - EAS ACTIVATION REQUESTED" at the top of the warning).

� 115 WUUS53 KLBF 052249 SVRLBF NEC089-149-052330- /O.NEW.KLBF.SV.W.0109.210805T2249Z-210805T2330Z/  BULLETIN - EAS ACTIVATION REQUESTED Severe Thunderstorm Warning National Weather Service North Platte NE 549 PM CDT Thu Aug 5 2021  The National Weather Service in North Platte has issued a  * Severe Thunderstorm Warning for...   Northeastern Rock County in north central Nebraska...   Southwestern Holt County in north central Nebraska...  * Until 630 PM CDT.  * At 548 PM CDT, a severe thunderstorm was located near Newport, or   15 miles east of Bassett, moving southeast at 40 mph.    THIS IS A DESTRUCTIVE STORM APPROACHING STUART!    HAZARD...Three inch hail and 70 mph wind gusts.    SOURCE...Radar indicated.    IMPACT...People and animals outdoors will be severely injured.            Expect shattered windows, extensive damage to roofs,            siding, and vehicles.  * Locations impacted include...   O'neill, O'Neill, Atkinson, Stuart, Newport and Emmet.  This includes the following highways...  Highway 20 between mile markers 265 and 308.  Highway 281 between mile markers 183 and 189.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  For your protection move to an interior room on the lowest floor of a building.  Prepare immediately for large hail and damaging winds. People outside should move immediately to shelter inside a strong building. Stay away from windows.  This is a dangerous storm. Prepare immediately for large destructive hail capable of producing significant damage. People outside should move to shelter inside a strong building,  and stay away from windows.  &&  LAT...LON 4256 9946 4274 9928 4252 9857 4224 9884 TIME...MOT...LOC 2248Z 300DEG 33KT 4262 9924  THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...3.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...70 MPH  $$  Sporer

On August 16, 2019 at 1:31 a.m. MDT, the National Weather Service in Cheyenne, Wyoming incorporated the "emergency" wording into a Severe Thunderstorm Warning. In this instance, the "severe thunderstorm emergency" statement was included to denote that three-inch (7.6 cm) diameter hail (as confirmed by storm spotter reports) was imminent in portions of Scotts Bluff, Banner and Sioux Counties in Nebraska, specifically areas around the towns of Scottsbluff and Gering. [29] 

� 187  WWUS55 KCYS 160731 SVSCYS  Severe Weather Statement National Weather Service Cheyenne WY 131 AM MDT Fri Aug 16 2019  NEC007-157-165-160815- /O.CON.KCYS.SV.W.0342.000000T0000Z-190816T0815Z/ Scotts Bluff NE-Banner NE-Sioux NE- 131 AM MDT Fri Aug 16 2019  ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 215 AM MDT FOR SCOTTS BLUFF...NORTHEASTERN BANNER AND SOUTHEASTERN SIOUX COUNTIES...  ...THIS IS A SEVERE THUNDERSTORM EMERGENCY FOR SCOTTSBLUFF AND  GERING!...  At 129 AM MDT, a severe thunderstorm was located near Scotts Bluff  National Monument, or near Scottsbluff, moving east at 40 mph. 3  INCH DIAMETER HAIL IS IMMINENT! PREPARE NOW FOR DESTRUCTIVE HAIL!  This is a very dangerous storm!  HAZARD...Three inch hail and 60 mph wind gusts.  SOURCE...Trained weather spotters.  IMPACT...People and animals outdoors will be severely injured.           Expect shattered windows, extensive damage to roofs,           siding, and vehicles.  Locations impacted include... Scottsbluff, Gering, Mitchell, Terrytown, Minatare, Wildcat Hills State Recreation Area, Lake Minatare Campground, Wildcat Hills Campground, Scotts Bluff National Monument, Hubbard Hill, Scottsbluff Airport, Lake Minatare, Lake Alice, Melbeta and McGrew.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  For your protection move to an interior room on the lowest floor of a building.  This is a dangerous storm. Prepare immediately for large destructive hail capable of producing significant damage. People outside should move to a shelter, inside a strong building and away from windows.  &&  LAT...LON 4185 10394 4233 10379 4230 10344 4209 10345       4209 10340 4200 10340 4198 10336 4156 10337       4170 10388 TIME...MOT...LOC 0729Z 288DEG 34KT 4189 10374  HAIL...3.00IN WIND...60MPH   $$  Lyons

See also

Related Research Articles

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The Storm Prediction Center (SPC) is a US government agency that 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).

<span class="mw-page-title-main">Lubbock tornado</span> 1970 F5 tornado in Texas

Portions of Lubbock, Texas, were struck by a powerful multiple-vortex tornado after nightfall on May 11, 1970, resulting in 26 fatalities and an estimated $250 million in damage. It was in its time the costliest tornado in U.S. history, damaging nearly 9,000 homes and inflicting widespread damage to businesses, high-rise buildings, and public infrastructure. The tornado's damage was surveyed by meteorologist Ted Fujita in what researcher Thomas P. Grazulis described as "the most detailed mapping ever done, up to that time, of the path of a single tornado." Originally, the most severe damage was assigned a preliminary F6 rating on the Fujita scale, making it one of only two tornadoes to receive the rating, alongside the 1974 Xenia tornado. Later, it was downgraded to an F5 rating. The extremity of the damage and the force required to displace heavy objects as much as was observed indicated that winds produced by vortices within the tornado may have exceeded 290 mph (470 km/h).

This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS is a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch. It defines precise meanings for nearly all of its weather terms.

<span class="mw-page-title-main">Tornado outbreak of January 2, 2006</span> Weather event in the United States

The tornado outbreak of January 1–2, 2006, was one of the largest tornado outbreaks ever recorded in the month of January. The outbreak affected much of the Central and Southern United States and produced 20 tornadoes. The tornadoes caused considerable damage in the states of Kentucky and Georgia. There were no tornado related fatalities and only minor injuries were reported.

This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.

In weather forecasting in the United States, "particularly dangerous situation" (PDS) is enhanced wording used by the National Weather Service to convey special urgency in some watch or warning messages for unusually extreme and life-threatening severe weather events, above and beyond the average severity for the type of event. It is used in the format "This is a particularly dangerous situation..." at the discretion of the issuing forecaster. A watch or warning bearing the phrase is referred to as a PDS watch or PDS warning as shorthand jargon.

A tornado emergency is an enhanced version of a tornado warning, which is used by the National Weather Service (NWS) in the United States during imminent, significant tornado occurrences in highly populated areas. Although it is not a new warning type from the NWS, issued instead within a severe weather statement or in the initial tornado warning, a tornado emergency generally means that significant, widespread damage is expected to occur and a high likelihood of numerous fatalities is expected with a large, strong to violent tornado.

A significant weather advisory was a hazardous weather statement issued by certain Weather Forecast Offices (WFO) of the National Weather Service (NWS) in the United States to alert the public of thunderstorm activity that is below designated severe criteria for and/or is not expected to produce severe weather. The title assigned to the advisory — alternately titled "significant weather alert" or referenced by its originating product, "special weather statement" — varied by the issuing WFO.

<span class="mw-page-title-main">Corn Belt derecho</span> Weather event

The Corn Belt derecho was a progressive derecho which affected a large area of the central United States on June 29, 1998. In the morning, thunderstorms, including a supercell, developed over South Dakota and tracked into central Iowa. As the thunderstorms reached central Iowa, a strong rear-inflow jet developed which caused the thunderstorm to take on a different characteristic, becoming a derecho. It traveled more than 600 miles in about ten hours, causing more than $125 million worth of widespread damage destruction, especially to crops, and was responsible for power outages to nearly a half a million people.

<span class="mw-page-title-main">Convective storm detection</span> Meteorological observation

Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus congestus to cumulonimbus, the latter producing thunderstorms associated with lightning and thunder. Those two types of clouds can produce severe weather at the surface and aloft.

A Special Weather Statement is a form of weather advisory. Special Weather Statements are issued by the National Weather Service of the United States (NWS) and the Meteorological Service of Canada (MSC). There are no set criteria for special weather statements in either country.

From May 3 to May 11, 2003, a prolonged and destructive series of tornado outbreaks affected much of the Great Plains and Eastern United States. Most of the severe activity was concentrated between May 4 and May 10, which saw more tornadoes than any other week-long span in recorded history; 335 tornadoes occurred during this period, concentrated in the Ozarks and central Mississippi River Valley. Additional tornadoes were produced by the same storm systems from May 3 to May 11, producing 363 tornadoes overall, of which 62 were significant. Six of the tornadoes were rated F4, and of these four occurred on May 4, the most prolific day of the tornado outbreak sequence; these were the outbreak's strongest tornadoes. Damage caused by the severe weather and associated flooding amounted to US$4.1 billion, making it the costliest U.S. tornado outbreak of the 2000s. A total of 50 deaths and 713 injuries were caused by the severe weather, with a majority caused by tornadoes; the deadliest tornado was an F4 that struck Madison and Henderson counties in Tennessee, killing 11. In 2023, tornado expert Thomas P. Grazulis created the outbreak intensity score (OIS) as a way to rank various tornado outbreaks. The tornado outbreak sequence of May 2003 received an OIS of 232, making it the fourth worst tornado outbreak in recorded history.

<span class="mw-page-title-main">1999 Bridge Creek–Moore tornado</span> 1999 tornado in Oklahoma, US

The 1999 Bridge Creek–Moore tornado was a large, long-lived and exceptionally powerful F5 tornado in which the highest wind speeds ever measured globally was recorded at 321 miles per hour (517 km/h) by a Doppler on Wheels (DOW) radar. Considered the strongest tornado ever recorded to have affected the metropolitan area, the tornado devastated southern portions of Oklahoma City, Oklahoma, United States while near peak intensity, along with surrounding suburbs and towns to the south and southwest of the city during the early evening of Monday, May 3, 1999. Parts of Bridge Creek were rendered unrecognizable. The tornado covered 38 miles (61 km) during its 85-minute existence, destroying thousands of homes, killing 36 people, and leaving US$1 billion in damage, ranking it as the fifth-costliest on record not accounting for inflation. Its severity prompted the first-ever use of the tornado emergency statement by the National Weather Service.

<span class="mw-page-title-main">Tornado outbreak of May 18–21, 2013</span> Tornado outbreak that struck the Midwestern United States on May 18–21, 2013

A significant and destructive tornado outbreak that affected parts of the Midwestern United States and lower Great Plains in mid-May 2013. This event occurred just days after a deadly outbreak struck Texas and surrounding southern states on May 15. On May 16, a slow moving trough crossed the Rockies and traversed the western Great Plains. Initially, activity was limited to scattered severe storms; however, by May 18, the threat for organized severe thunderstorms and tornadoes greatly increased. A few tornadoes touched down that day in Kansas and Nebraska, including an EF4 tornado near Rozel, Kansas. Maintaining its slow eastward movement, the system produced another round of severe weather nearby. Activity significantly increased on May 19, with tornadoes confirmed in Oklahoma, Kansas, Iowa, Missouri, and Illinois. In Oklahoma, two strong tornadoes, one rated EF4, caused significant damage in rural areas of the eastern Oklahoma City metropolitan area; two people lost their lives near Shawnee. The most dramatic events unfolded on May 20 as a large EF5 tornado devastated parts of Moore, Oklahoma, killing 24 people. Thousands of structures were destroyed, with many being completely flattened. Several other tornadoes occurred during the day in areas further eastward, though the majority were weak and caused little damage.

<span class="mw-page-title-main">National Weather Service Norman, Oklahoma</span> Weather Forecast Office of the National Weather Service

National Weather Service - Norman, Oklahoma is a Weather Forecast Office (WFO) of the National Weather Service based in Norman, Oklahoma, which is responsible for forecasts and the dissemination of weather warnings and advisories for central and most of western Oklahoma, and western portions of north Texas. It is located in the National Weather Center on the University of Oklahoma campus, where it acts as one of the NOAA Weather Partners, a group of close-together weather-related agencies of the National Oceanic and Atmospheric Administration. NWS Norman is currently overseen by Mark Fox, who serves as the Meteorologist In Charge of the office.

<span class="mw-page-title-main">2021 Naperville–Woodridge tornado</span> 2021 tornado in Illinois, U.S.

In the evening hours of June 20, 2021, an intense tornado affected the Chicago suburbs of Naperville, Woodridge, Darien, Burr Ridge, and Willow Springs in DuPage and Cook Counties in Illinois. It was the strongest tornado spawned by a surface low over Wisconsin, which spawned a total of four tornadoes across Illinois and Indiana. The tornado, striking well after dark, had a path length of 14.8 mi (23.8 km) and reached a width of 600 yd (550 m), while causing 11 injuries, downing thousands of trees, and inflicting widespread property damage primarily across Naperville and Woodridge.

References

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  5. ↑ "Storm Prediction Center Frequently Asked Questions (FAQ)". www.spc.noaa.gov. Retrieved 2018-09-09.
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