A four-day, once-in-a-generation weather event is pounding the middle of the U.S. with destructive tornadoes and life-threatening flooding.

Parts of the storm-swamped South were under new tornado and flood alerts Sunday ... Some rivers in Kentucky were expected to exceed their flood stages by upward of 15 feet as waterways started ...

Day after day of heavy rains have pounded the central U.S., rapidly swelling waterways and prompting a series of flash flood emergencies in from Texas to Ohio.