197 FXUS01 KWBC 180810 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 409 AM EDT Thu Sep 18 2025 Valid 12Z Thu Sep 18 2025 - 12Z Sat Sep 20 2025 ...An upper trough across the northern/central Plains and Mississippi Valley will bring unsettled weather in the form of marginally severe storms and isolated flooding potential through the next few days... ...Tropical moisture from Mario pushes into the Southwest, with flash flooding possible today and Friday... ...The Ohio and Tennessee Valleys will see high temperatures as much as 10-15 degrees warmer than average as afternoon highs reach th 90s... The upper-low over the Central U.S. will continue to bring chances for showers and thunderstorms through the next few days. For severe weather, the Storm Prediction Center has a Marginal Risk for severe weather centered from Oklahoma into Missouri for today. The main weather hazards should be some hail and perhaps a strong wind gust or two. Otherwise, Friday and Saturday should continue to see general scattered thunderstorms in the presence of the upper low across the Midwest with the shear and instability generally favoring sub-severe thunderstorms. The flash flood threat should be marginal for today into the weekend across the Plains and Midwest, though the disturbance will advect in modest moisture at the surface for an isolated locally heavy storm or two. Post tropical Mario continues to bring some tropical moisture near southern coastal California, promoting the possibility for locally heavy thunderstorms today and Friday across California. Rainfall totals are expected to reach 1-3" and rainfall rates >1"/hr, and there is a chance for flash flooding in sensitive terrain and localized urban flooding. Flash Flood Watches have been issued for most of southern California; follow your local weather forecast office for specific information. New Mexico and Arizona will also see an increase in showers and thunderstorms and a possibility for localized flash flooding today into Friday. The rest of the CONUS will generally be mild as a more zonal weather pattern is in place. The Ohio and Tennessee Valleys will be particularly warm with high temperatures in the lower to middle 90s as upper level ridging is located over the region and from warm air advection ahead of the upper trough in the central part of the country. Most of the country will be 5-10 degrees above average in high temperatures. The Southwest will see below average temperatures with increased clouds and rainfall. A backdoor cold front into the Northeast will bring afternoon temperatures back into the 60s and 70s this weekend. Tropical moisture from the Caribbean Sea will continue to bring numerous widespread showers and thunderstorms over southeast Florida, with urban areas being the most sensitive to localized flash flooding. With the ample deep layer moisture, Weather Prediction Center does have a Marginal Risk (level 1/4) for Excessive Rainfall over part of southeast Florida. Wilder/Oudit Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php Clear: NO $$