The remnants of Isaac will meander east across Illinois tonight and into south-central Indiana by Monday. Scattered to numerous showers and a few thunderstorms will continue over the Wabash and Ohio Valleys ahead of the storm system. A brief spin-up tornado, isolated damaging winds, and locally heavy rainfall can be expected with the strongest storms over east central Kentucky this evening. Thus a Tornado Watch is in effect for east central Kentucky through 11 pm EDT...10 pm CDT. Periodic showers and isolated storms will continue Monday and Tuesday as the storm system slowly weakens and moves off to the east. Some moderate to heavy showers or storms may cause localized minor flooding or ponding of water roadways. Storm total rainfall amounts could reach 1 to 3 inches over parts of southern Indiana, and 1 to 2 inches over portions of central Kentucky, with locally higher amounts. The Ohio River Forecast Center has a very helpful page describing past and future rainfall.
The map below shows the Tornado Watch in effect. Monitor the latest forecasts from the Storm Prediction Center. A Hazardous Weather Outlook issued by NWS Louisville provides local information on this system. Continue to closely monitor the progress of the remnants of Isaac and the latest forecasts, especially if your travels this holiday weekend take you near or through the path of the storm.
Below is an image from the Hydrometeorological Prediction Center depicting the expected rainfall through Tuesday night. Locally higher amounts are possible, which could lead to a localized flash flood threat. Keep up to date of the latest forecasts and track of the storm remnants as a slight shift could lead to different rainfall amounts.