PHILADELPHIA (KYW Newsradio) — The National Weather Service (NWS) plans to start sending alert messages to people’s cellphones during what it deems “destructive” thunderstorm conditions.
The alerts, similar to ones for tornadoes or flash flood warnings, will warn the public about the potential impacts of thunderstorm winds and hail in their area. The service will start on July 28.
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NWS categorizes severe thunderstorm warnings into three damage threat levels, from highest to lowest impact: destructive, considerable, and base.
Destructive damage is defined as baseball-sized hail and/or winds of at least 80 mph. Warnings in this category will automatically activate a Wireless Emergency Alert and notify people’s smartphones within the area.
A considerable damage threat includes golf ball-sized hail and/or 70 mph winds. Base, or baseline, threats are quarter-sized hail and/or 58 mph winds.
Considerable and base threats will not activate a Wireless Emergency Alert.
The destructive category is meant to alert the public that a life-threatening event is underway and urgent action is needed, as it may cause significant damage.
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Other weather alert systems, like online updates and NOAA Weather Radio, will continue to be used.
On average, only 10% of all severe thunderstorms nationwide reach the destructive level each year, according to NWS.