127 FXUS01 KWBC 200631 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 230 AM EDT Sun Sep 20 2026 Valid 12Z Sun Sep 20 2026 - 12Z Tue Sep 22 2026 ...Excessive Rainfall threat across portions of the Midwest, Ohio Valley, Mid-Atlantic, Plains, northern/central Rockies through Sunday... ...Chances for severe thunderstorms across portions of the central/southern Plains into Midwest and Ohio Valley/Mid-Atlantic through Sunday... ...Severe thunderstorm threat continues into Monday for portions of the central and southern Appalachians and Southeast... A upper-level low and associated shortwave energy will continue eastward into the northern Plains through Sunday. At the surface, the slow moving frontal boundary and shortwave trough across portions of the Rockies/Plains into the Ohio Valley and Northeast will support scattered showers and thunderstorms along the boundary. Repeated convection may develop and organized convection may lead to high rainfall rates as the disturbances interact with unstable moist airmass. Therefore, excessive rainfall and flash flooding concerns will prevail across portions of the northern/central Rockies, Plains, Midwest, Ohio Valley, and portions of the Mid-Atlantic through Sunday, especially where soils remain saturated from previous rainfall. Additionally, Storm Prediction Center (SPC) has highlighted a risk for severe thunderstorms capable of producing hail and severe winds across portions of the central/southern Plains into the Ohio Valley and Mid-Atlantic. On Monday, the frontal system continues to push southeastward, while moist and unstable airmass remain entrenched across portions of the Plains, Ohio Valley/Tennessee Valley, and Mid-Atlantic. Organized convection may lead to excessive rainfall concerns over parts of the Mid-Atlantic and southern Plains, while a severe thunderstorm threat shifts into portions of the central/southern Appalachians and the Southeast. Across the Southeast, showers and thunderstorms are expected, particularly during the afternoon and evening when instability increases. Localized downpours will be possible from slow moving storms, leaving areas across South Florida vulnerable to excessive rain through Monday. Hot and humid conditions continue across central and southern Plains, Tennessee Valley, and lower Mississippi Valley, while temperatures moderate across the northern Plains, Midwest, and Great Lakes behind the trough and associated frontal system. Oudit Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$