Severe thunderstorms can be life-threatening, with hazardous conditions ranging from tornadoes, large hail storms, and widespread straight-line winds called derechoes to cloud-to-ground lightning and flash flooding. Beginning August 2, the National Weather Service (NWS) will better convey the severity and potential impacts from thunderstorm winds and hail by adding a “damage threat” tag to Severe Thunderstorm Warnings, similar to their Tornado and Flash Flood Warnings. The NWS developed three categories of damage threat for Severe Thunderstorm Warnings. The categories, in order of highest to lowest damage threat, are destructive, considerable and base. These tags and additional messaging are designed to promote immediate action based on the threats.
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 Wireless Emergency Alert (WEA) on smartphones within the warned area. 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 at 1 inch (quarter-sized) hail and/or 58 mph thunderstorm winds and will not activate a WEA. When no damage threat tag is present, damage is expected to be at the base level. On average, only 10% of all severe thunderstorms nationwide reach the destructive category each year. The new destructive thunderstorm category conveys to the public that urgent action is needed and 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. The addition of damage threat tags is of the broader Hazard Simplification Project to improve communication of watches and warnings to the public. All NWS Severe Thunderstorm Warnings will continue to be issued and distributed via www.weather.gov, NOAA Weather Radio, the Emergency Alert System and the local media. Alerts are also distributed to Newport News residents who sign up for NN Alert, the city’s official notification system. Learn how to stay safe in a severe thunderstorm by visiting the NWS website. |
