Looking at the depth change map, it seems like areas farther north in Wisconsin get screwed more, possibly due to a longer fetch over the warm water. Temps in downtown Chicago when the 1st wave starts are still near/at freezing.
Something that has been discussed in the past for different storms - could convection in the warm sector lead to a more suppressed solution? SPC has an enhanced risk for tomorrow.
If I was in McHenry County I'd be feeling pretty good right now. In downtown Chicago not so much. Well, we can't say we haven't been through plenty of storms like that.