Dense fog and light showers started the day Thursday with mostly cloudy skies lasting through much of the afternoon and evening. Isolated thunderstorms have developed over west-central and central Illinois where skies cleared a little during the afternoon. Those isolated storms will continue to move south through the evening.
Drizzle is possible later this evening over northern Illinois and southern Wisconsin as another disturbance moves in from the northwest. An increase in showers will be likely by Friday morning as the disturbance to the northwest shifts into the Midwest. Scattered showers will continue through the early afternoon with temperatures only warming into the upper 50s. A stronger low pressure system will move from the Plains into Missouri Friday, and then into southern Illinois by Saturday morning. Rain showers will likely increase through the evening Friday across central Illinois, lifting into northern Illinois overnight into Saturday.
Heaviest rainfall may fall just shy of the immediate Stateline Friday into Saturday as bands of rain rotate around the low to the south. If, however, the low shifts a little further north then the northern band of rain could move through northeast and north-central Illinois, possibly leading to another half an inch to three quarters of an inch by Saturday evening.
Temperatures will also be cool Saturday thanks to a northeast breeze. Highs will only manage the low 50s. Sunday high pressure will move back in with a little more sunshine warming temperatures back up near 60 degrees.