Scattered to numerous slow-moving thunderstorms will develop through the day. These storms will produce torrential downpours which will overwhelm drainage systems and small creeks, leading to areas of flash flooding. * WHAT. Flash flooding caused by excessive rainfall is possible. * WHERE. Areas of southern Illinois along and south of Highway 13 and all of western Kentucky. * WHEN. From 10 AM CDT this morning through 12 AM CDT. * IMPACTS. Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Creeks and streams may rise out of their banks. Flooding may occur in poor drainage and urban areas. * ADDITIONAL DETAILS. - Scattered to numerous thunderstorms will develop across southern Illinois and western Kentucky from late this morning through late tonight. Areas that see thunderstorms could receive 1.5 to 3.0 inches of rain in just one or two hours, with locally higher amounts up to 4 inches possible.