Thunderstorm activity last night shoved the warm front into southern Wisconsin this morning, becoming stationary. This front will become a cold front and sag south this afternoon which could trigger an isolated t-storm across the southeast. The main event will arrive after dark into early Thursday morning as upper level support arrives.
The strongest storms will be south of the WI/IL tonight. Northern Illinois will have the best chance for a strong/severe storm possibly containing large hail or damaging winds. An isolated tornado cannot be ruled out. North of the border in southern Wisconsin the passage of the cold front will reduce instability, still some elevated instability should remain for scattered t-storms. Depending on the exact position as storms arrive from the west, places like Janesville and Kenosha will be at risk for strong/severe storms.
Like last night in central Wisconsin; timing is unfavorable for severe weather across the yellow highlighted area and forcing is less impressive relatively speaking. Yet parameters still suggest the potential for severe overnight (northern Illinois) so will continue to mention it.
THURSDAY NIGHT & BEYOND
The main upper level trough will approach Wisconsin Thursday night. This will be the best chance for rain and t-storms statewide for the rest of the week. The threat for severe weather remains somewhat uncertain especially with surface warm front being pushed into northern Illinois by Thursday morning. By Friday I expect some clearing.