A potent combination of high humidity and an approaching frontal system is expected to spark widespread thunderstorms — some severe — along much of the East Coast. The system will arrive overnight from Sunday,

Sunday and Wednesday could feature severe weather outbreaks across the Mississippi and Ohio valleys, while Monday could bring storms to the Deep South and East Coast.

Forecasters warn of widespread damaging winds, very large hail and tornadoes, from Texas to the East Coast starting on Sunday.