Strong thunderstorms were expected to come out of eastern South Dakota Wednesday evening and spread across most of west central Minnesota through the night.
Much of west central Minnesota is expected to get 3 to 5 inches of rain by Friday, according to meteorologist Jim Taggart at the National Weather Service office in Chanhassen.
"There will be wave after wave (of storms), through Thursday night," he said.
A flood watch was 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 Minnesota River is at "action level" in Granite Falls and Montevideo, which is about one foot below flood stage. This is highly unusual for this time of year, local officials say. Officials in the area appeared to be gearing up for heavy rains. Portable pumps were located near manholes in Granite Falls by Wednesday morning. During heavy rains in August, the city used portable pumps to relieve pressure on the sewer system at locations throughout the community after the system was overwhelmed.
The storms that began to arrive late Wednesday "are getting tropical moisture from what was formerly Hurricane Karl," Taggart said.