Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 352 PM EDT Wed Mar 17 2021 Valid 00Z Thu Mar 18 2021 - 00Z Sat Mar 20 2021 ...An intense low pressure system is expected to bring widespread thunderstorms across the Deep South with dangerous severe weather likely through Thursday... ...Threat of excessive rainfall will expand into the Southeast tonight... ...Critical fire weather threat along the Rio Grande River Valley tonight... A low pressure system currently moving through Oklahoma will be the impetus for flash flooding and severe weather concerns across the Deep South over the next 24 hours. This area of low pressure will continue pulling moisture from the Gulf of Mexico and spreading it over the the Lower Mississippi Valley and Southeast tonight and tomorrow. This will contribute to continued atmospheric destabilization and an increased threat of widespread severe thunderstorms and tornado outbreaks across the region. Increased moisture flow into the area has also lead to a heightened risk of flash flooding across the Middle/Lower Mississippi Valley, Tennessee Valley and Southeast tonight. The low pressure system will expand into the east coast tomorrow as it continues to generate thunderstorms and potential severe weather activity in the Southeast, Mid-Atlantic and Ohio Valley. This system, and most of its impacts, should move off into the Atlantic by Friday afternoon leaving behind light snow and windy conditions in its wake across much of the Northeast. Elsewhere, a new system will enter the Northwest on Thursday and produce some measurable mountain snow for the Olympic and Sierra. Coastal and lower elevation areas will experience rain. This same dynamic will continue across the intermountain west as the system redevelops over the region on Friday morning. Temperatures will cool down across the eastern half of the country, as the storm system moves through. The Northern Plains will experience a gradual warm-up heading into the weekend as a warm front lifts through the region. Much of the Rio Grande Valley is under an Elevated or Critical Fire Weather area for tonight as dry and windy conditions are expected to fuel potential fire activity. Kebede Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php