Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 352 AM EDT Tue May 20 2025 Valid 12Z Tue May 20 2025 - 12Z Thu May 22 2025 ...Severe Weather and Flash Flooding risks shift into the Ohio/Tennessee/Mississippi Valleys today, followed by the East Coast on Wednesday... ...Above average temperatures across southern tier states; below average temperatures across the northern tier... A strong low pressure system will spread scattered showers and thunderstorms across the Mississippi Valley today, then the Ohio Valley/East Coast on Wednesday. There's an Enhanced Risk (level 3/5) of Severe Thunderstorms for portions of the Mid/Deep South to Tennessee Valley and Cumberland Plateau, according to the Storm Prediction Center. Multiple rounds of severe storms capable of producing some strong tornadoes, scattered to widespread wind damage and large to isolated significant severe hail will be possible. A broad Slight Risk (at least 15%) of Excessive Rainfall is in effect for portions of the Midwest and Ohio/Tennessee Valleys today as well. Moist soils in the Mid-Altantic/Northeast will support a Marginal Risk (at least 5%) of Flash Flooding on Wednesday when today's storms move into the region. 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 Wednesday. Meanwhile, a zonal and 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. Elsewhere, some light snow is possible over the mountains of northwest Wyoming today. Things dry out across the Northwest on Wednesday. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php