I'm watching storms move from southeast to northwest over southern Illinois. You can see on today's surface map that the scattered storms ahead of the front are following the surface winds and pushing back toward the low pressure system.
Because of a deepening low, the rain is going to arrive a little later than yesterday's forecast. As the front draws near on Friday night and Saturday, rain will concentrate just ahead of the boundary. Rain will move in from the southwest, but the individual showers and thunderstorms will travel from southeast to northwest. Here's a look at potential rainfall through Saturday night:
The bigger concern will be the potential for localized flooding over the weekend. As you can see by the 5-day rainfall total forecast from HPC. Again, because the rainfall will be spread over several days, flash flooding should not be an issue. The problem will come from showers and storms that "train" or move over already rain-soaked areas.