A frontal boundary will approach the area early Thursday and looks to stall somewhere near the Ohio River Valley through at least Sunday. The airmass south of this front will become very moist, which will allow any storms that develop to drop heavy rains. Should areas receive multiple rounds of this heavier rain, localized flash flooding would occur. At this time the heaviest forecast rainfall totals from tonight through Saturday look to be south of the Ohio River, but a lot will depend on where the front stalls and how it meanders over the region. The images below represent the Weather Prediction Center's forecast for rainfall totals from now through Thursday evening (in the left panel), now through Friday evening (in the center panel), and now through next Monday.