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

A dangerous tornado outbreak which started on Friday evening continued into the first half of the weekend with nearly 2 dozen deaths across the nation's heartland and South.

Millions of Americans across the country are on alert for a severe weather outbreak as violent, long-track tornadoes with damaging winds of up to 80 mph and large hail are expected across the Midwest and South with the cross-country storm moving east.

A monster storm system carrying a high risk tornado threat is barreling through the Southeast after unleashing deadly tornadoes, fierce winds and devastating damage across the Plains and Midwest.

Alabama’s PDS tornado watch is the second PDS watch of the day. Parts of Mississippi and Louisiana were put under a PDS watch earlier on Saturday.

An "outbreak" of tornadoes and severe thunderstorms is expected through Saturday night in Alabama, Mississippi, Louisiana, and other southern states.