National Weather Service United States Department of Commerce

A year ago, on August 10, 2020, a line of intense thunderstorms called a “derecho” resulted in four deaths, dozens of injuries, and significant damage across the Midwest, including damage locally across parts of central Indiana. The National Oceanic and Atmospheric Administration (NOAA) estimates that this single day of extreme weather cost over $11 billion, making it the most expensive thunderstorm event in modern U.S. history.  A thorough review of this event can be found on the August 10, 2020 Derecho Story Map webpage.



Radar reflectivity of the August 10, 2020 Derecho at one-hour time steps


warn path

Map of Severe Thunderstorm Warnings issued by the NWS for the derecho event.


Severe Weather Communication Improvement

To better communicate the threat of such a destructive severe thunderstorm, the NWS has begun issuing Severe Thunderstorm Warnings using damage threat categories. Warnings tagged with DESTRUCTIVE will trigger a Wireless Emergency Alert on your smartphone/mobile device. The plans for implementing Wireless Emergency Alerts for severe thunderstorms were underway when the derecho occurred, but the event hastened implementation of this capability, so the public can be warned more directly. Our Webstory contains additional details about this important update. 


Additional Information Resources

Severe Storms of August 10, 2020 ( (central Indiana review)


NWS Storm Prediction Center

NWS Severe Thunderstorm Safety

August 10, 2020 Derecho Story Map