Just How Severe Is A Severe Thunderstorm Warning? NWS Helps Out With New Alert Tags.
Life-threatening thunderstorms can come in many forms and levels of severity. That's why the National Weather Service is adding two new categories to its Severe Thunderstorm Warnings.
You'll see these new alerts on your smartphone beginning July 28.
The three categories of damage threat are:
Destructive: This means damage threat is at least 2.17 inch diameter (baseball-sized) hail and/or 80 mph winds. This category will automatically activate a Wireless Emergency Alert (WEA) on smartphones within the area affected. This is the most severe damage threat.
Considerable: This damage threat is at least 1.75 inch diameter (golf ball-sized) hail and/or 70 mph winds. This will not activate a WEA.
Base or baseline: This category does not change. Its threat is one-inch hail and/or 58 mph winds. This will not activate a WEA.
Here is an example of a destructive alert, tweeted by the National Weather Service.
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.— National Weather Service (@NWS) July 22, 2021
Read more: https://t.co/Vu9HyjsoRw pic.twitter.com/6Qi6s5l8ce
The National Weather Service says that 13 of the 22 costliest weather disasters in 2020 were severe thunderstorms and would have triggered the new "destructive" WEA alert. That includes the costliest thunderstorm in U.S. history — the $11 billion derecho that hit Iowa in August 2020.
The addition of the damage threat tags is part of the weather service's Hazard Simplification Project, the goal of which is to improve communication with the public.