The Full Wiki

More info on Tornado warning

Tornado warning: Map

Advertisements
  
  

Wikipedia article:

Map showing all locations mentioned on Wikipedia article:

A tornado warning (SAME code: TOR) is an alert issued by government weather services to warn an area that a tornado may be imminent. It can be issued after either a tornado or funnel cloud has already been spotted, or if there are radar indications that a tornado may be possible. When this happens, the tornado siren may start going off in that area, letting people know that a tornado was seen or is forming nearby.

Early History

The first official tornado forecast (and tornado warning) was made by United States Air Force Capt. (later Col.) Robert C. Miller and Major Ernest Fawbush, on March 25, 1948. The USAF pioneered tornado forecasting and tornado warnings, mainly due to the Weather Bureau's strong discouragement/ban on the use of the word "tornado" in forecasts or statements, fearing that it would cause the public to panic if they predicted tornadoes. In 1950, the Weather Bureau revoked their ban on the word "tornado", thus allowing public tornado warnings.

Tornado Alert

For many years up until the early 1980s an intermediate type of tornado advisory known as a Tornado Alert was defined by the National Weather Service and issued by local offices thereof. A Tornado Alert indicated that tornado formation was imminent and in theory covered situations such as visible rotation in clouds and some other phenomena which are portents of funnel formation. The use of this advisory began to decline after 1974 but was still listed on public information materials issued by various media outlets, local NWS offices, &c. for another decade or so.

The kinds of situations which called for Tornado Alerts in the past now generally result in a Tornado Warning with clarifying verbiage specifying that the warning was issued because rotation was detected in one way or another, that a wall cloud has formed, and so on.

The Tornado Alert was eliminated both because it was made largely obsolete by the advent of Doppler weather radar which can detect tornado formation earlier -- often before it is visible to the naked eye of trained spotters and other members of the public -- and with fewer false-positives and also it was also eliminated to reduce confusion amongst the public, with the last mentioned issue first discussed in earnest following the 3-4 April 1974 Super Outbreak. The preferred response to both the Tornado Alert and Warning is to take shelter immediately, so it could be seen as splitting hairs especially since prediction has improved.

Criteria

A tornado warning is issued when:



It is also sometimes issued when, depending on the circumstances:



A tornado warning means there is immediate danger for the warned and immediately surrounding area -- if not from the relatively narrow tornado itself, from the severe thunderstorm producing (or likely to produce) it. All in the path of such a storm are urged to take cover immediately, as it is a life-threatening situation. A warning should not be confused with a tornado watch (issued by a national guidance center, the Storm Prediction Center) which only indicates that conditions are favorable for the formation of tornadoes.

Generally (but not always), a tornado warning also indicates that the potential is there for severe straight-line winds and large hail from the thunderstorm. A severe thunderstorm warning can be upgraded suddenly to a tornado warning should conditions warrant.

In the United Statesmarker, local offices of the National Weather Service issue warnings for tornadoes and severe thunderstorms based on the path of a storm, although entire counties are sometimes included, especially if they are small. Warnings were issued on a per-county basis before October 2007.

In Canadamarker, similar criteria are used and warnings are issued by regional offices of the Meteorological Service of Canada of Environment Canada in Vancouvermarker, Edmontonmarker, Torontomarker, Montrealmarker and Halifaxmarker.

Tornado warnings are generated via computer then disseminated through various communication routes accessed by the media and various agencies, on the internet, to NOAA satellites, and on NOAA Weather Radio. Civil defense sirens are also activated for the affected areas if present.

Advances in technology, both in identifying conditions and in distributing warnings effectively, have been credited with reducing the death toll from tornadoes. The average warning times have increased substantially to about 15 minutes; and in some cases to more than a one hour's warning of impending tornadoes. The U.S. tornado death rate has declined from 1.8 deaths per million people per year in 1925 to only 0.11 per million in 2000. Much of this change is credited to improvements in the tornado warning system.

Recognition

The SKYWARN program, which teaches lay people how to spot tornadoes, funnel clouds, wall clouds, and other weather phenomena, is offered by the National Weather Service. In tandem with Doppler radar information, eye witness reports can be very helpful for warning the public of an impending tornado, especially when used for ground truthing.

Other Spotter Networks and private spotters relay information to the National Weather Service for public safety.

Tornado Emergency

When a large, extremely violent tornado is about to impact a densely populated area, the Weather Service has the option of issuing a severe weather statement with enhanced wording; this is called a tornado emergency. This category of weather statement is the highest and most urgent level relating to tornadoes; the ladder is as follows: relevant verbiage in the current day's Convective Outlook, Public Severe Weather Outlook mentioning tornado potential (not all outlooks do -- they are issued when derecho (q.v.) formation is forecast, which can reduce the likelihood of tornadoes after a certain severity level), Tornado Watch, Particularly Dangerous Situation Tornado Watch, Tornado Alert (formerly), Tornado Warning, and the Tornado Emergency variant. Tornado warnings can also be intensified by added wording mentioning that the storm is life-threatening, it is an extremely dangerous situation, a large, violent and/or destructive tornado is on the ground, &c.

Examples



BULLETIN - EAS ACTIVATION REQUESTEDTORNADO WARNINGNATIONAL WEATHER SERVICE WICHITA KS837 PM CDT WED JUN 11 2008

THE NATIONAL WEATHER SERVICE IN WICHITA HAS ISSUED A

  • TORNADO WARNING FOR...

 SALINE COUNTY IN CENTRAL KANSAS.



  • UNTIL 930 PM CDT.



  • AT 835 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED

 A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS
 DANGEROUS STORM WAS LOCATED 10 MILES SOUTHWEST OF BROOKVILLE...OR
 11 MILES EAST OF ELLSWORTH...MOVING EAST AT 45 MPH.



  • LOCATIONS WITHIN THE WARNING INCLUDE...

 ASSARIA...BRIDGEPORT...BROOKVILLE...GLENDALE...GYPSUM...NEW
 CAMBRIA...SALINA...SMOLAN...SALINA AIRPORT.



THIS IS A DANGEROUS STORM. MOVE INTO YOUR TORNADO SHELTER NOW! IF NOUNDERGROUND SHELTER IS AVAILABLE...MOVE INTO AN INTERIOR ROOM ON THELOWEST FLOOR OF A STURDY STRUCTURE.

LARGE HAIL AND DAMAGING THUNDERSTORM WINDS ARE ALSO EXPECTED WITHTHIS STORM.

HEAVY RAINFALL FROM THE STORM MAY PRODUCE LOCALIZED FLOODING. DO NOTDRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEYWILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE.

LAT...LON 3860 9735 3860 9793 3862 9794 3889 9793
     3896 9735

TIME...MOT...LOC 0137Z 260DEG 39KT 3870 9800

$$

HOWERTON



See also



References


Embed code:
Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message