About 78 million people were under severe weather advisories from the National Weather Service, which warned of flash floods, long-track tornadoes and baseball-sized hail.

Meteorologists said the Ohio and Tennessee valleys face the highest risk, especially throughout the afternoon and evening hours. Intense storm conditions may be felt as far south as the Gulf Coast, and as far east as western portions of Virginia and the Carolinas, the weather service added.

More than 300,000 utility customers across West Virginia, Kentucky, Ohio and other states were without power as of Tuesday afternoon as winds as high as 92 mph battered the region, according to a database maintained by USA TODAY.

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