Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 436 PM EDT Fri Aug 20 2021 Valid 00Z Sat Aug 21 2021 - 00Z Mon Aug 23 2021 ...There is a Slight Risk of excessive rainfall over parts of the Mid-Atlantic, Tennessee/Lower Mississippi Valleys, and Upper Midwest through Saturday morning... ...There is a Slight Risk of severe thunderstorms over parts of the Northern/Central Plains and the Upper/Middle Mississippi Valley through Saturday morning... ...Tropical Storm Henri is forecast to become a hurricane and move toward Southern New England with a Moderate Risk of excessive rainfall starting as early as Saturday night... Tropical Storm Henri is forecast to become a hurricane on Saturday morning as the storm heads northeastward towards Southern New England; forecast to make landfall on Sunday. Overnight Saturday, Henri starts producing rain over Southern New England, and the rain will become heavier as the storm moves onshore. Therefore, the WPC has issued a Moderate Risk of excessive rainfall with rain. The associated heavy rain will create numerous areas of flash flooding. Furthermore, many streams may flood, potentially affecting larger rivers through Sunday into Monday morning. Elsewhere, a front extending from Upper Midwest to the Southern High Plains and Southern Rockies will move eastward to the Lower Great Lakes to the Middle Mississippi Valley by Sunday evening. Moisture streaming northward from the Western Gulf Coast will aid in producing showers and thunderstorms along and ahead of the boundary through Saturday night. The showers and thunderstorms will produce heavy rain over parts of the Upper Midwest through Saturday morning. 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 Saturday morning. Additionally, the SPC has issued a Slight Risk of severe thunderstorms over the Northern/Central Plains and the Upper/Middle Mississippi Valley through Saturday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. The severe thunderstorm and the excessive rainfall threat diminish on Saturday. Meanwhile, tropical moisture, an old boundary, and upper-level energy will aid in producing showers and thunderstorms over the Tennessee/Lower Mississippi Valleys through Sunday 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 Saturday morning. The excessive rainfall threat will continue over the region on Saturday into Sunday morning. Furthermore, tropical moisture and a weak upper-level low over the Mid-Atlantic will produce showers and thunderstorms through Sunday morning. The showers and thunderstorms will produce heavy rain over parts of the Mid-Atlantic through Saturday morning. 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 Saturday morning. The excessive rainfall threat decreases slightly on Saturday into Sunday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php