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.

After deadly storms scourged the Heartland, volunteers are gathering from across the area to help with relief and recovery efforts.

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