A major storm is on the move from Texas into the Gulf Coast states where “violent,” “long-track” tornadoes are possible Thursday.

The “violent” definition means the winds of the tornadoes could be 166 mph or greater with ratings of EF-4 or EF-5. These tornadoes are often “long-track,” which means they could be on the ground for at least 25 miles.

So far, this storm system has already produced a tornado in central Texas and three dozen reports of huge damaging hail. Some baseball-size hail has already been reported.

Now, this storm system will move into the Ohio and Tennessee River Valleys with a trailing cold front all the way down to the Gulf Coast.

Ahead of this storm, supercell thunderstorms are expected to break out Thursday afternoon and evening from Mississippi to Kentucky with damaging winds, violent tornadoes and baseball size hail.

NOAA’s Strom Prediction Center issued a “high risk” for severe weather in Tennessee, Alabama and Mississippi.

Overall, more than 18 million people could see severe weather Thursday from eastern Texas all the way to southern Ohio, where damaging winds, large hail and tornadoes will be possible.