Fueled by warm, humid air moving in from the Gulf, the severe weather threat will expand farther east and south on Sunday over the Mississippi Valley. Forecasters warned people in states including Tennessee, Alabama, Mississippi, Georgia, Oklahoma and Missouri to keep up with weather updates from officials.

More storms will brew over the southern United States this weekend and there is the potential for a few tornadoes by Sunday.

Large swaths of the country are preparing for severe weather. A risk for tornados and blizzard conditions is taking shape in the central U.S. as a major storm system moves across the country. CBS News Philadelphia Grant Gilmore reports.