The dynamic storm from Friday through Sunday had earned an unusual “high risk” designation from weather forecasters.

In some extreme cases, thunderstorms can spawn a derecho, a long-lived windstorm with gusts over 100 mph, strong enough to cause widespread destruction. If a severe thunderstorm warning mentions damaging winds or a derecho, take cover immediately—just as you would for a tornado.

A severe storm on Monday swept through the U.S. Southeast and Mid-Atlantic, bringing thunderstorms, hail, damaging winds and the potential for tornadoes. Days earlier, the same ferocious weather system spawned violent twisters,

The weakening but still volatile weather system was moving Monday into the US Southeast and Mid-Atlantic, bringing thunderstorms, hail, damaging winds, and the potential for more tornadoes.