Scattered rain showers and isolated thunderstorms developed late Thursday afternoon across central and southern Wisconsin, but are now quickly moving out over Lake Michigan. The rain/storm activity developed as an upper level disturbance moved in from the High Plains. That disturbance will remain north of the state line, leaving much of northern Illinois rain free for the evening.
Clouds will decrease in coverage, and have already started to, leaving our skies mostly clear during the overnight. Temperatures will dip into the mid 50s for the start of Friday. Similar to Thursday, Friday will begin sunny but cloud cover will be quick to develop during the afternoon. Surface temperatures will warm back into the upper 70s and low 80s, with a slightly cooler air mass just above the surface. This change in temperature will allow air to quickly rise throughout the atmosphere. That rising air reaches a point in the atmosphere where it begins to condense, forming the cumulus cloud bases. In an atmosphere that has moisture, as well as some sort of lifting force (upper level disturbance/frontal boundary, etc) rain showers may develop. But in an atmosphere that is a little more dry it is likely all you’ll see is the cloud cover.
Cumulus clouds are expected to develop during the afternoon Friday, but an incoming cold front will sweep through Friday late afternoon and evening. The arrival of the front may spark an isolated shower or two during the evening. Mostly dry skies are expected through the weekend.