WCCB Charlotte's CW New smartphone weather emergency alert to begin July 28th July 22, 2021 Starting July 28th your smartphone will alert you when severe thunderstorm warnings are deemed destructive. This is not app-based, it is free and already on your phone – you just have to make sure it is turned on. The criteria for a destructive threat is at least 2.75 inch diameter hail and/or 80 mph thunderstorm winds. Starting July 28, Severe Thunderstorms deemed “destructive” will activate a Wireless Emergency Alert (WEA) on smartphones. Criteria for a destructive threat is at least 2.75 inch diameter hail and/or 80 mph thunderstorm winds.