A low pressure system will be tracking across northern Wisconsin on Thursday, which will bring numerous showers and thunderstorms to Road America during the day. The two practice sessions that afternoon are likely to be impacted. This system will be east of Wisconsin by Friday, but there may be some lingering showers in the area as the upper level trough remains overhead. These should just be scattered to isolated light showers, so the impact risk is very low.
High pressure starts to build over the region on Saturday, providing mostly sunny skies for Saturday and Sunday. Temperatures will be on the warm side for Saturday, but humidity levels will be comfortable with a north wind. Sunday may be a few degrees cooler, with slightly lower humidity levels.