Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Sun Apr 19 2020 Valid 12Z Sun Apr 19 2020 - 12Z Tue Apr 21 2020 ...Widespread severe weather and flash flooding are expected today and 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. Moisture and instability currently returning north from the Gulf of Mexico will interact with a front draped across the Gulf Coast states as an upper-level trough crosses the southern Plains and moves toward the lower Mississippi Valley. This will result in multiple waves of low pressure developing along the front which are expected to move rapidly eastward across the Deep South today and then consolidate toward the Mid-Atlantic coast early Monday. Today is expected to be a very active day in terms of severe weather, with a focus on a broad area from eastern Texas eastward to the Carolinas, and which also just one week ago saw a major severe weather outbreak with numerous tornadoes. This next round of severe weather for today and tonight is expected to bring another threat of large hail, damaging winds and tornadoes to many of the same areas. The Storm Prediction Center has highlighted portions of the Deep South in a Moderate Risk of severe weather going through Monday morning, with the greatest threat depicted from north-central Louisiana eastward to southern and central Mississippi, southern and central Alabama, and south-central Georgia. In addition to the severe weather, heavy rainfall is expected and locally several inches of new rainfall may fall over areas that have received above normal rainfall over the past few weeks. Given the wet antecedent conditions, this additional rainfall will foster renewed flooding and flash flooding concerns across these areas. In fact, the Weather Prediction Center has issued a Moderate Risk of excessive rainfall from central Mississippi eastward to South Carolina, and thus there is a sizable overlap with the aforementioned severe weather hazards. The intensifying and consolidating waves of low pressure are forecast to exit the Mid-Atlantic coast on Monday and move rapidly out to sea which will allow the severe weather and excessive rainfall threats to come to an end. Elsewhere, a cold front will bring main light precipitation across portions of the Northeast today, with cooler and drier weather following on Monday as this front then moves offshore. There will be yet another cold front that will drop southeast from Canada and bring another round of light precipitation across the Great Lakes on Monday. Meanwhile, a mix of rain and snow is forecast to track across the interior Northwest and through the northern and central Rockies today and tonight. A couple inches of new snowfall are expected for the higher elevations. Additionally, portions of the Southwest are expected to see a couple rounds of showers and maybe a few thunderstorms by Monday as an upper trough begins to move inland off the Pacific Ocean. Temperature-wise, generally cooler than normal temperatures can be expected across a good portion of the northern Plains, Midwest and the eastern U.S. going into early next week as reinforcing cold fronts continue to drop southeast Canada. Cooler than normal temperatures will also tend to focus over the Southwest as there will be an increase in clouds and shower activity. By contrast, the warmest weather with above normal temperatures are expected for parts of southern Texas and the Rio Grande Valley, and also for areas of south Florida. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php