The past 72 hours have featured relentless rains across the southern Plains, with wide swaths of 2 to 5 inches and totals in some spots exceeding half a foot. Walters, in southwest Oklahoma, has logged 10.14 inches since Sunday night, and another round of heavy rains is slated for Thursday night.

Millions across the United States are being impacted by severe storms bringing torrential rain and flash flooding. In Texas and Oklahoma, high waters prompted evacuations and rescues. Now, another round of potentially dangerous thunderstorms is on the way.

The south-central U.S. is facing a "heightened" risk of flash flooding into Thursday following days of deadly storms across a region that's spanned from Texas to the Northeast, the National Weather Service warns.