Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 415 PM EDT Tue Sep 14 2021 Valid 00Z Wed Sep 15 2021 - 00Z Fri Sep 17 2021 ...Topical Storm NICHOLAS is forecast to weaken to a Tropical Depression slowly where the main hazard is heavy rainfall... ...There is a High Risk of excessive rainfall over parts of the Central Gulf Coast through Wednesday morning... ...There is a Slight Risk of severe thunderstorms over parts of the Great Lakes/Ohio Valley and parts of the Central High Plains through Wednesday morning... ...Temperatures will be 10 to 15 degrees above average over parts of the Northern High Plains... Topical Storm NICHOLAS is forecast to weaken to a Tropical Depression slowly where the main hazard is heavy rainfall. NICHOLAS will slowly move eastward to Louisiana and lose its tropical characteristics by Thursday evening. The system will produce heavy rain over parts of the Central Gulf Coast through Thursday. Therefore, the WPC has issued a High Risk of excessive rainfall over the Central Gulf Coast associated with the heavy rain through Wednesday morning. Severe, widespread flash flooding is expected with NICHOLAS. Areas that normally do not experience flash flooding will flood. Lives and property are in great danger through Wednesday morning. The excessive rainfall threat will weaken slightly to a Moderate Risk of excessive rainfall over parts of the Central Gulf Coast on Wednesday into Thursday morning. Similarly, the excessive rainfall threat will continue to lessen on Thursday, with a Slight Risk of excessive rainfall over the region. However, the excessive rainfall threat may linger as with other systems that have slowly spun down over the Gulf Coast region. Meanwhile, a front extending from the Great Lakes roughly westward to the Central High Plains will slowly move eastward, moving off the Northeast Coast by Thursday evening, while parts of the boundary dissipate. Moisture pooling along the front will aid in producing showers and thunderstorms along and ahead of the boundary, and some of the storms will become severe. Therefore, the SPC has issued a Slight Risk of severe thunderstorms over parts of the Northeast and Mid-Atlantic through Sunday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. In addition, along the western end of the front, the SPC has issued a Slight Risk of severe thunderstorms over parts of the Central High Plains through Wednesday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and minimal tornado threat. As the boundary moves eastward, the threat for severe thunderstorms will move eastward over the Northeast into parts of the Central Appalachians/northern Mid-Atlantic on Wednesday as the SPC has issued a Slight Risk of severe thunderstorms there for Wednesday into Thursday. Showers and thunderstorms will continue over parts of the Mid-Atlantic into the Southeast through Thursday evening. Furthermore, a front moving onshore over the Pacific Northwest will move eastward to the Upper Midwest by Thursday, producing showers and thunderstorms. However, there will be a threat of fire weather over parts of the Northern High Plains until the front passes through Wednesday morning as Red Flag Warnings are issued over the area due to high temperatures, low moisture content, and gusty winds. Temperatures will be 10 to 15 degrees above average over parts of the Northern High Plains. Ziegenfelder Graphics are available at www.wpc.ncep.noaa.gov/basicwx/basicwx ndfd.php