A slow-moving low pressure system will spin above the Great Lakes region Thursday night through Saturday. Rain will be scattered in coverage, on & off at times, but where it does rain it will linger. One or two places could exceed 3.0" by Saturday night. Uncertainty is relatively high.
Here is a loop of the next 60hrs or so. You will see in the loop how the scattered, convective character of the event will make it tough to pin down the heaviest rains. The WPC and medium range models put the Sheybogan, WI area along Lake Michigan at the best chance for rainfall exceeding 2.0". Convective models look different putting heaviest rains across the southwest, so this should be interesting.
There are some dry spots out there so the rain will be welcome news for many. With tendency toward convective Heavy Rain events going straight to runoff, it's probably drier than the data suggests over the last 60 days.