Monday, March 25, 2013

Severe Weather Awareness Week in Nebraska: Weather Definitions


Advisory:  An advisory is issued when a hazardous weather is occurring, imminent or likely. Advisories are for less dangerous conditions than warnings that cause significant inconvenience.

Watch:      A watch means weather conditions are favorable for dangerous weather to occur.  A watch means the potential or conditions exist for a dangerous weather event.

Warning:  A weather warning means that a dangerous weather event is imminent. Immediate action must be taken to protect life and property. People need to take action as soon as possible.

  • Severe Thunderstorm Watch:  Conditions are favorable for the development of severe thunderstorms in and close to the watch area. A severe thunderstorm contains large damaging hail of 1 inch in diameter or larger, and/or damaging winds greater than 58 mph or greater. Isolated tornadoes are also possible but not expected to be the dominant severe weather event.
  • Severe Thunderstorm Warning: A severe thunderstorm is indicated by Doppler weather radar or sighted by spotters. A severe thunderstorm contains large damaging hail of 1 inch in diameter or larger, and/or damaging winds of 58 mph or greater. These warnings are currently issued on a polygonal basis.
  • Tornado Watch:  Conditions are favorable for the development of severe thunderstorms and tornadoes in and close to the watch area.
Particularly dangerous situation Tornado Watch: Conditions are favorable for the development of severe thunderstorms and destructive tornadoes in and close to the watch area. These watches are occasionally issued, and usually mean that a major tornado outbreak is possible, where the potential for multiple violent (EF-4 and EF-5) tornadoes exists. These watches are usually issued for a larger area by the Storm Prediction Center in Norman, Oklahoma than a regular Tornado Watch, and are usually valid for a longer period of time than a regular Tornado Watch. This type of watch is usually only reserved for forecast "high-end" severe weather events.
Particularly dangerous situation Tornado WarningA Large tornado has been confirmed to be producing damage and is moving into and through the warned area. It is usually issued as the initial tornado warning or as a complete re-issuance of the previous tornado warning. These may also include wording for a Tornado Emergency.

Tornado Emergency:  Sent as a "severe weather statement" or a complete re-issuance of the tornado warning, this is an unofficial, high end tornado warning issued when a violent tornado is expected to impact a heavily populated area. Such warnings have been issued for the 1999 F5 Moore, Oklahoma tornado, the 2007 EF5 Greensburg, Kansas tornado, and the 2011 EF4 Tuscaloosa, Alabama tornado.

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