Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 AM EDT Tue Sep 12 2017 Valid 12Z Tue Sep 12 2017 - 12Z Thu Sep 14 2017 ...Irma has become a Post-Tropical Cyclone... ...Temperatures will be 10 to 20 degrees below average over parts of the Tennessee/Lower Mississippi Valleys and parts of the Southeast... Irma has become a Post-Tropical Cyclone and will slowly wind down on Tuesday and Wednesday. The associated region of low pressure will move northwesterly to Southern Illinois by Wednesday evening. The system will produce rain over parts of the Southern Ohio Valley and Tennessee/Lower Mississippi Valleys eastward to parts of the Southeast/Southern Mid-Atlantic that will expand into parts of the Northern Ohio Valley and into parts of the Northern Mid-Atlantic on Tuesday into Tuesday evening. Overnight Tuesday, the rain will expand into parts of the Great Lakes and the Middle Mississippi Valley that will end over the Middle Mississippi Valley by Wednesday evening. In addition, embedded thunderstorms will develop over parts of the Southern Mid-Atlantic that will move northward into parts of the Northern Mid-Atlantic and the Lower Great Lakes by Wednesday morning and continue into Wednesday evening. Furthermore, tropical moisture will move into Southern Florida overnight Tuesday that will aid in producing scattered showers and thunderstorms over the Southeastern and Southern Florida on Wednesday. Meanwhile, an upper-level low off the Southern California Coast will slowly move inland over Southern California on Tuesday into Wednesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php