The official 24-hour rainfall record for the state of Kentucky, 10.48 inches observed at Louisville (Jefferson County) on March 1, 1997, was the result of a powerful storm system. The combination of moisture from the Gulf of Mexico and a stationary front across the state produced heavy rains and thunderstorms until a cold front pushed all of the storms to the east and out of Kentucky.
The May Day Floods of 2010 impacted portions of Kentucky and Tennessee, causing substantial damage to the area. Rainfall totals over 10 inches across widespread areas lead to significant river flooding. You can learn more about this historic event by reading the detailed Storm Event Report provided by the Louisville National Weather Service.