It has been raining for several hours in the Redwood Falls area and other areas south of Willmar, and more storms are coming tonight.
Thunderstorms are expected to come out of eastern South Dakota and spread across most of west central Minnesota over the next several hours, according to meteorologist Jim Taggart at the National Weather Service office in Chanhassen.
"There will be wave after wave after that, through Thursday night," he added.
Taggart said much of west central Minnesota is expected to get 3 to 5 inches of rain by Friday.
A flood watch has been issued for much of the area, and flood warnings are in effect along the Minnesota River. The flooding is expected because much of the ground in the area is already saturated by abundant rain this summer and fall.
The storms that arrive later tonight "are getting tropical moisture from what was formerly Hurricane Karl," Taggart said.