Tornadoes and violent winds flattened homes and ripped apart buildings from Oklahoma to Indiana in the first round of storms that are expected to bring record-setting rains and life-threatening flash floods across the nation's midsection in the coming days.

A storm system sweeping over large areas of the U.S. South and Midwest has resulted in at least 16 weather-related deaths, with overnight tornado and flash flood warnings setting up more severe weather that forecasters say could cause rising waterways for days to come.

Heavy rain will drench the Northeast on Monday as several states are reeling from last week's powerful spring storms that unleashed major flooding and left at least 21 people dead. Last week's storms wreaked havoc over the Midwest and the mid-South and later turned east.