Tornado watch

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Severe thunderstorm with a clear slot near main updraft core. Typically a tornado, if present, will form in this area.

A tornado watch (SAME code: TOA; sometimes referred to as a "red box" by meteorologists and storm chasers) is issued when weather conditions are favorable for the development of severe thunderstorms that are capable of producing tornadoes. A tornado watch therefore implies that it is also a severe thunderstorm watch. A tornado watch must not be confused with a tornado warning.

A watch does not mean that the severe weather is actually occurring, only that conditions have created a significant risk for it. If severe weather actually does occur, a tornado warning or severe thunderstorm warning will be issued.

[edit] Information included in a tornado watch

	Tornado watch Oklahoma An example of a tornado watch issued in Oklahoma
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In the United States, the Storm Prediction Center (a national guidance center of the National Weather Service) issues watches for areas likely to produce tornadoes and severe thunderstorms. The watch boxes (or weather watches, WWs) are usually issued in the format of x miles north and south, or east and west, or either side of a line from y miles direction of city, state, to z miles another direction of another city, state. For example: "50 miles either side of a line from 10 miles northeast of Columbia, South Carolina to 15 miles south-southwest of Montgomery, Alabama". ("Either side" means perpendicular to the center line.) When displayed on a map, they appear as a red outline. In addition, a list of all counties included in its area of responsibility is now issued by each NWS forecast office for each watch.

[edit] PDS watches

In the event that a tornado watch is likely to lead to a major tornado outbreak along with possible destructive winds and hail, enhanced wording with the words particularly dangerous situation (PDS) can be added to the watch; this is occasionally issued.

[edit] Tornado watches in Canada

In Canada, the criteria used is the same and watches are issued by regional offices of the Meteorological Service of Canada of Environment Canada in Vancouver, Edmonton, Toronto, Montreal and Halifax, on a county or regional basis.

[edit] See also

• Severe weather terminology (United States)
• Mesoscale discussion

[edit] References

[edit] External links

• Current Watches In the United States