Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 411 PM EDT Sun Apr 19 2020 Valid 00Z Mon Apr 20 2020 - 00Z Wed Apr 22 2020 ...Widespread severe weather and flash flooding are expected through tonight from the Lower Mississippi Valley to the Southeast... The synoptic pattern across the U.S. will continue to support an active storm track across the southern tier states. Multiple clusters of strong to severe thunderstorms continuing heavy rain continue to develop across the interior sections of the Deep South this Sunday afternoon. These thunderstorms and heavy rains are in response to moisture and instability lifted along a stationary front as a low pressure system develops and rapidly approaches from Texas. Multiple low pressure waves will continue to develop along the stationary front, leading to more heavy thunderstorms to impact the interior Southeast through tonight. The Storm Prediction Center continues to highlight areas from north-central Louisiana eastward to southern and central Mississippi, southern and central Alabama, and south-central Georgia as having the greatest threat of severe weather through tonight. In addition to the severe weather, the associated heavy rain will likely result in flash flooding in parts of the areas. The low pressure waves are expected to move rapidly eastward and consolidate into a low pressure system, which is forecast to exit the East Coast on Monday. Some strong thunderstorms are still possible from Georgia to the Carolinas Monday morning before the storms rapidly move out to sea during the afternoon. Elsewhere, a cold front will bring mainly light precipitation across portions of the Northeast through tonight, followed by a return of cooler and drier conditions on Monday behind the front. There will be yet another cold front that will drop southeast from Canada and bring another round of light wintry mixed precipitation across the Great Lakes on Monday. By Tuesday, the mixed precipitation is expected to move into the Northeast, with rain and some thunderstorms possibly extending as far south as the central Appalachians. Meanwhile, a mix of rain and snow is forecast to track across parts of the western U.S. from California through the central Rockies for the next couple of days, where accumulating snowfall is expected for the higher elevations. This is in response to yet another upper trough edging into the Southwest from the Pacific Ocean, and will set the stage for another low pressure system to develop over the southern High Plains on Tuesday. Showers and thunderstorms are expected to expand eastward into the southern Plains as snow continues to fall in the higher elevations of Colorado. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php