CHARLESTON, W.Va. — Beginning Monday, Aug. 2, all branches of the National Weather Service will begin adding a “damage threat” tag to Severe Thunderstorm Warnings, to better convey the severity and potential impacts from thunderstorm winds and hail.
The National Weather Service (NWS) recently announced the development of three categories of damage threat for Severe Thunderstorm Warnings. The categories, in order of highest to lowest damage threat, are destructive, considerable, and base.
According to the NWS Charleston, these tags and additional messaging are designed to promote immediate action, based on the threats, and send out a Wireless Emergency Alert (WEA) for a Severe Thunderstorm Warning. The alerts, only used for destructive, would go to every cell phone much like a Tornado Warning or Amber Alert.
“That will set off wireless emergency alerts, which are the alerts built into everyone’s cell phones. We can really increase awareness of those high-end thunderstorms,” Tony Edwards, Warning Coordination Meteorologist for NWS Charleston told MetroNews.
The criteria for a destructive damage threat is at least 2.75 inch diameter (baseball-sized) hail and/or 80 mph thunderstorm winds. Warnings with this tag will automatically activate a WEA on smartphones within the warned area, according to the NWS.
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 activate a WEA.
The criteria for a baseline or “base” severe thunderstorm warning remains unchanged, 1.00 inch (quarter-sized) hail and/or 58 mph thunderstorm winds. This will not activate a WEA. When no damage threat tag is present, the damage is expected to be at the base level.
Severe thunderstorms can be life-threatening, but not all severe storms are the same. Starting Aug 2, NWS will add a “damage threat” tag to Severe Thunderstorm Warnings, triggering Wireless Emergency Alerts for “destructive” storms.https://t.co/uO5H84SOqr pic.twitter.com/Aa96VaeDJk
— NWS Charleston, WV (@NWSCharlestonWV) July 26, 2021
According to the NWS, only 10 percent of all severe thunderstorms reach the destructive category each year, nationwide. Most of these storms are damaging wind events such as derechoes and some of the larger, more intense thunderstorms, called “Supercell” storms that can typically produce very large hail in their path.
“I don’t think we’re going to employ it very often around here because it is a really major storm that will get that tag. But it’s something that when we do have those major events, we can increase awareness,” Edwards said.
The NWS called the destructive thunderstorm category “needed” as it’s a life-threatening event
All NWS Severe Thunderstorm Warnings will continue to be issued and distributed via weather.gov, NOAA Weather Radio, Emergency Alert System and through dissemination systems to its emergency managers and partners. The addition of damage threat tags are part of the broader Hazard Simplification Project to improve communication of watches and warnings to the public, according to a release.
Thirteen of the 22 costliest weather disasters in 2020 in the United States were severe thunderstorms, the NWS said.