Severe thunderstorm warnings to activate a Wireless Emergency Alert on smartphones

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NOAA Example Alert(WMC)
Published: Jul. 22, 2021 at 5:35 PM CDT
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MEMPHIS, Tenn. (WMC) - The Mid-South has its share of severe thunderstorm warnings in a give year. The National Weather Service plan to better communicate the severity and potential impacts from severe thunderstorm wind and hail by adding a “damage threat” tag to Severe Thunderstorm Warnings starting July 28th, 2021. Severe Thunderstorms deemed “destructive” will activate a Wireless Emergency Alert (WEA) on smartphones.

Wireless Emergency Alerts (WEAs) are short emergency messages from authorized federal, state, local, tribal and territorial public alerting authorities that can be broadcast from cell towers to any WEA‐enabled mobile device in a locally targeted area. Wireless providers primarily use cell broadcast technology for WEA message delivery. WEA is a partnership among FEMA, the Federal Communications Commission (FCC) and wireless providers to enhance public safety.

WEAs can be sent to your mobile device when you may be in harm’s way, without the need to download an app or subscribe to a service. WEAs are messages that warn the public of an impending natural or human-made disaster. The messages are short and can provide immediate, life-saving information.

Criteria for a destructive threat is at least 2.75 inch diameter hail and/or 80 mph thunderstorm winds. There are three categories that range from the highest to lowest threats. They are destructive, considerable and base threats.

  • DESTRUCTIVE DAMAGE THREAT: at least 2.75 inch diameter (baseball-sized) hail and/or 80 mph thunderstorm winds. Warnings with this tag will automatically activate a Wireless Emergency Alert (WEA) on smartphones within the warned area.
  • CONSIDERABLE DAMAGE THREAT: at least 1.75 inch diameter (golf ball-sized) hail and/or 70 mph thunderstorm winds. This will not activate a WEA.
  • BASE DAMAGE THREAT: Severe thunderstorm warning remains unchanged using the standard criteria of one inch (quarter-sized) hail and/or 58 mph thunderstorm winds. This will not activate a WEA. When no damage threat tag is present, damage is expected to be at the base level.

According to the National Weather Service, only 10 percent of all severe thunderstorms reach the destructive category each year on average, nationwide. Most of these storms are damaging wind events such as derechoes. Some of the larger, more intense “Supercell” thunderstorms can produce very large hail in their path. The new destructive thunderstorm category conveys to the public urgent action is needed, that a life-threatening event is occurring and may cause substantial damage to property. Storms categorized as destructive will trigger a WEA to your cell phone.

All National Weather Service Severe Thunderstorm Warnings will continue to be issued and distributed via, NOAA Weather Radio, Emergency Alert System and through dissemination systems to all 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.

Spencer Denton

First Alert Storm Tracking Team

Facebook: Meteorologist Spencer Denton

Twitter: @dentonwx

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