Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 PM EDT Sun Aug 22 2021 Valid 00Z Mon Aug 23 2021 - 00Z Wed Aug 25 2021 ...Tropical Storm Henri is forecast to slowly weaken over parts of Southern New England before exiting the country on Tuesday evening, with a Moderate Risk of excessive rainfall through Tuesday morning... ...There is a Slight Risk of excessive rainfall over parts of the Southeast through Monday morning... ...There is a Slight Risk of severe thunderstorms over parts of the Northern/Central Plains and the Middle Mississippi Valley through Monday morning... ...High heat indices across the Lower Mississippi Valley and portions of the Southern Plains have led to Heat Advisories across the region... Tropical Storm Henri, currently over parts of New England, is forecast to slowly weaken over the region before exiting the country, moving into the Canadian Maritimes on Tuesday evening. Check with the NHCâ€s latest bulletin for the most up-to-date track and intensity of Henri. Henri will produce heavy rain over parts of New England through Tuesday. Therefore, the WPC has issued a Moderate Risk of excessive rainfall for the heavy rain over the region lasting into Tuesday morning. The heavy rain will create numerous areas of flash flooding. Furthermore, many streams may flood, potentially affecting larger rivers from through Tuesday morning. Meanwhile, tropical moisture, an old boundary, and upper-level energy will aid in producing showers and thunderstorms over the Southeast into parts of the Central Gulf Coast through to Monday morning. The showers and thunderstorms will produce heavy rain over the area. Therefore, the WPC has issued a Slight Risk of excessive rainfall with these thunderstorms. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable through Monday morning. The excessive rainfall threat will wane over the region by Monday morning. A front over the Northern/Central Plains into parts of the Upper Mississippi Valley will move eastward into the Upper Mississippi Valley before dissipating on Monday, as another front moves out of the Northern Rockies/Great Basin. The system will produce showers and thunderstorms across the Upper Midwest through overnight Sunday. Some of the thunderstorms may become severe. Therefore, the SPC has issued a Slight Risk of severe thunderstorms over parts of the Northern/Central Plains and the Middle Mississippi Valley through Monday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. The severe thunderstorm threat will lessen slightly on Monday into Tuesday. Elsewhere, Red Flag Warnings and an Elevated fire weather risk are forecast over parts of the Northern High Plains/Northern Rockies Monday morning. Air Quality Alerts are also in effect throughout Central California, parts of the Pacific Northwest, and Northern High Plains/Northern Rockies due to thick wildfire smoke. Meanwhile, Temperatures across the Lower Mississippi Valley and portions of the Southern Plains will gradually turn hotter on Monday into Tuesday as an upper-level ridge builds over the southern tier. Oppressive heat will already be found across the Lower Mississippi Valley and parts of the Southern Plains on Sunday evening, as heat and humidity push heat indices up to around 110F. As a result, Heat Advisories have been issued for eastern Oklahoma, northeast Texas, Arkansas, Mississippi, and Louisiana. Furthermore, the area will have the possibility of record high minimum temperatures through Wednesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php