Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 346 PM EDT Tue May 20 2025 Valid 00Z Wed May 21 2025 - 00Z Fri May 23 2025 ...Severe Weather and Flash Flooding expected over the Ohio/Tennessee/Mississippi Valleys today; Mid-Atlantic/Northeast tomorrow... ...Above average temperatures across southern tier states; below average temperatures across the northern tier... After an active 48 hours of severe weather and heavy rainfall over the nation's midsection, well defined low pressure is forecast to shift unsettled weather eastward into the Ohio/Tennessee/Lower Mississippi Valleys today, and Mid-Atlantic/Northeast tomorrow. Per the Storm Prediction Center, the forecast remains on track for an Enhanced Risk (level 3/5) of severe thunderstorms, where tornadoes (some strong), scattered to widespread damaging winds, and isolated significant severe hail are all on the table through tonight as storms form ahead of a sweeping cold front. Excessive rainfall rates and periodic cell training within the same storms should also support isolated to scattered instances of flash flooding across much of the same area today, where a Slight Risk (level 2/4) of Excessive Rainfall is in effect. By tomorrow, moist soils in the Mid-Altantic/Northeast will support a Slight Risk (at least 15%) of Excessive Rainfall as several rounds of storms are expected. A more unstable environment to the south will allow for increased thunderstorm activity and the potential for isolated severe storms along the Southeast/Mid-Atlantic Coast. Upper troughing over southern Canada and the northern tier of the U.S. will allow for a cooler airmass to park over the region through late this week. High temperatures in the 40s and 50s will be 20-35 degrees below average for parts of the Northern Plains and Upper Midwest today and tomorrow. Meanwhile, a quasi-zonal, ridge-like pattern over the southern tier will supply ample warm air into the region over the next few days. Widespread high minimum temperature records may be tied or broken across the Southeast and Southern California over the next couple of nights. Asherman/Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php