Unseasonably warm and increasingly more humid air from the south will be drawn up and over the cool air to the north, causing a widespread area of moderate to heavy rain through Thursday.
The heaviest rainfall will extend from southern Minnesota through the upper Great Lakes and into central Ontario from Wednesday night through Thursday.
Between 2 and 4 inches of rain could fall over this area leading to flooding of rivers and poor drainage areas.
Severe thunderstorms with damaging wind and hail will impact the region from Kansas to southern Minnesota during the afternoon and evening Thursday.
Story by AccuWeather.com Senior Meteorologist Brett Anderson