Destructive severe warned thunderstorms will trigger mobile phone alerts starting early August
The most destructive severe warned thunderstorms will trigger mobile phone alerts starting on August 2nd.
RICHMOND, Va. (WWBT) - On August 2, the National Weather Service (NWS) will make a change to how it issues severe thunderstorm warnings.
The NWS will now break down severe thunderstorm warnings into three different levels of damage threat to distinguish between high impact and low impact events. From high impact to low impact, severe thunderstorms will be considered “destructive, considerable, and base”.
The worst damage threat (destructive) will trigger an alert text sent to mobile phones in the warned area. Only about 10% of severe thunderstorms fall into this category in a given year. For a severe thunderstorm to be considered destructive, it must have at least 2.75 inch diameter (baseball-sized) hail and/or 80 mph thunderstorm winds. Most of these warnings will be issued for derechos or supercell/rotating thunderstorms capable of life-threatening destruction.
The criteria for a considerable damage threat is at least 1.75 inch diameter (golf ball-sized) hail and/or 70 mph thunderstorm winds. This will not trigger a cell phone alert.
The base criteria for a severe thunderstorm warning will not change (it was previously 60mph thunderstorm winds or 1 inch diameter hail and will remain that way moving forward, and will not trigger a phone alert).
If you have the NBC12 First Alert Weather App, you will continue to receive alert notifications anytime a severe thunderstorm warning is issued for your area, regardless of the threat level.
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