UPDATE FRI - Bumping the TARGET up to STRONG for northern Illinois. This will primary impact the WI/IL border region; the rest of Wisconsin will not have severe weather threat. Perhaps a t-storm or rumble of thunder across southern WI.
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Large differences between 00EC and 06GFS/NAM regarding timing.
The EC is more aggressive with morning rain convection which could put a damper on evening redevelopment chances. Nonetheless, in any situation; the warm front will be pushing north into Wisconsin and a thunderstorm or two could fire along it. Timing is flexible, perhaps during the mid-day hours but most likely afternoon/evening. The upper level support is a potent short wave moving in from the southwest and where exactly that goes will make a huge difference. Severe risk is low outside of the jet streak. Inside the jet streak (southern WI or Illinois) you could have one or two severe storms.
At this stage going to stay with a GENERAL risk. Added TARGET for where models seem to bring t-storm activity most commonly. Will need an update on Friday.