As communities in the central US grapple with widespread devastation from a line of deadly storms that spawned dozens of tornadoes this week, more grave threats to the region are underway: additional severe thunderstorms and relentless rain with the potential to trigger “generational” flooding into the weekend.

Potentially historic flooding is underway Thursday in the Mississippi and Ohio valleys, as repeated rounds of rain pummel several states in America’s heartland.

Flash flooding due to relentless rainfall can be life-threatening and catastrophic in some communities into this weekend, then river flooding on the major rivers could lead to weeks of inundation, great economic loss.

Relentless thunderstorms continued to drench hard-hit parts of the central U.S., threatening "catastrophic" flooding.

More than a dozen twisters ripped across the US Wednesday, including a tornado in Owasso, Oklahoma, that damaged buildings, utility poles, and trees.

A massive storm hitting the central U.S. on Wednesday could spin up damaging tornadoes and dump heavy rain from northern Texas to the Great Lakes.

Videos show a massive tornado moving through Lake City, Arkansas. Roughly 15 million people, from Ohio to Mississippi, are under tornado watches. The weather event is also set to bring multiple days of nearly nonstop rain,

Deadly storms and flooding rains left a path of destruction across 14 states in the US South and Midwest, knocking out power to more than 400,000 customers.