Violent tornadoes ripped through parts of the U.S., wiping out schools and toppling semitractor-trailers in several states.

Meanwhile, the severe weather threat will linger through Sunday from Florida northward into the upper Ohio River Valley, forecasters warned.

On Monday, 8 million people were under winter storm watches and warnings, although the storms' impacts were less severe than those over the weekend.

A series of storms that kicked up wildfires, tornadoes and dust while barreling across seven states over the weekend have left at least 39 people dead and dozens injured.Scattered tornadoes in Missouri killed at least a dozen people,

A storm entering on the West Coast will transition into the Rockies and Plains this week, sparking numerous threats ranging from snow-induced travel delays, wildfire threats, damaging winds and severe t-storms. "This discovery is both surprising and exciting."