Severe thunderstorms can be life-threatening, but not all severe storms are the same. Hazardous conditions range from tornadoes, large hail storms, and widespread straight-line winds called derechoes, to cloud-to-ground lightning and flash flooding. Last summer, the National Weather Service began better conveying the severity and potential impacts from thunderstorm winds and hail by adding a “damage threat” tag to Severe Thunderstorm Warnings, similar to our Tornado and Flash Flood Warnings.
“Destructive” and “Considerable” Damage Threat Categories
We 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.
On average, 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. The new destructive thunderstorm category conveys to the public urgent action is needed, 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.