People will soon be alerted on their smartphones of severe thunderstorms that are deemed "destructive."
Starting July 28, the National Weather Service (NWS) will activate a Wireless Emergency Alert (WEA) on smartphones for "destructive" thunderstorms, a news release says, similar to what it does for tornado and flash flood warnings.
This means that people with smartphones will be alerted about life-threatening thunderstorms if they're in the warning area.
This new category aims at conveying to the public they must take urgent action as a life-threatening event is occurring that may cause "substantial damage to property," NWS says.
Not all storms are considered "destructive" — only those with a threat of 2.75-inch in diameter (baseball-sized) hail and/or winds of 80 mph qualify as "destructive" and will trigger a WEA alert on cell phones.
Nationwide, only about 10% of storms reach the "destructive" category every year. The NWS says most of these storms end up being damaging wind events like derechos, while some are larger, more intense storms called Supercell storms, which can typically produce "very large hail."
The other category of severe storms is "considerable" which is when a storm could produce at least 1.75-inch diameter (golf ball-sized) hail and/or winds of 70 mph.
The baseline for a severe thunderstorm warning is 1-inch hail (quarter-sized) and/or 58 mph winds.
Neither "considerable" or severe thunderstorm warnings will activate a WEA warning.
NWS says all severe thunderstorm warnings will continue to be issued via the agency's website, NOAA Weather Radio and the Emergency Alert System. NWS just added the damage threat tags as part of its Hazard Simplification Project to improve communication of watches and warnings to the public.
Of the 22 costliest weather disasters in 2020, 13 were severe thunderstorms (none in Minnesota), NWS says. This new "destructive" category would have activated the WEA for most of them, including the derecho in Iowa in August 2020, which was the costliest thunderstorm in U.S. history at $11 billion.