It was dry on both Thursday and Friday, and things will be dry for much of the day Saturday. The forecast changes by late Saturday evening and Saturday night as a cold front approaches from the north. That front will support the development of some scattered rain showers in far northern Illinois into Wisconsin. Much of the activity will hold off until roughly midnight. As Futurecast shows to the left, there is not much rain showing up across the area. The coverage of rain showers will not be very impressive. In addition, rainfall totals do not look to be overly concerning.
The Futurecast model we use here in the Weather Center only depicts three-hundredths of an inch of rainfall in the bucket by Sunday morning. While that likely is a little below what will fall, it represents the fact that there likely won't be much in the way of heavy or concentrated rain. It wouldn't be completely shocking to see many backyards avoid the rain shower activity completely Saturday night, especially folks to the south and west of Rockford. The other aspect of Saturday night's rain shower threat is the potential for thunder and lightning.
That is due to small amounts of instability that will be in place along and ahead of the incoming cold front. Instability can be referred to as "food" for thunderstorms to use to maintain themselves. With even minor instability in place (as shown to the left) there could be a few rumbles of thunder with any of the strong showers that develop and slide through the area. We dry out by early Sunday morning and remain dry into the middle of next week.