Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 428 AM EDT Mon Apr 03 2017 Valid 12Z Mon Apr 03 2017 - 12Z Wed Apr 05 2017 ...Threats of severe weather and flash flooding will impact areas across the Southern Mississippi Valley and the Southeast today... ...Expect snow to occur through the Rockies and portions of the Great Basin and Northern Plains over the next couple of days... Severe weather and flash flooding will be of concern across the Lower Mississippi Valley and towards the Southeastern U.S. today. The close proximity of a surface low pressure system and associated cold frontal boundary to the Gulf Coast will allow for an abundant amount of warm, moist, and unstable air to pull into the Lower Mississippi Valley Region and points just eastward. This will lead to widespread heavy rain as well as strong to potentially dangerous convective development. The Storm Prediction Center has a large part of southern and central Louisiana, central and southern Mississippi, and far west-central Alabama outlined in an Enhanced Risk area today for severe storm development (please check www.spc.ncep.noaa.gov for more information). In addition, a slight risk of severe weather exists in surrounding areas. Flash flooding is already ongoing across portions of the Lower Mississippi Valley, especially near the Gulf Coast, and is expected to continue throughout the day while slowly moving eastward. The Weather Prediction Center has outlined portions of the eastern Gulf Coast (including far southeast Mississippi, southern Alabama, and the western panhandle of Florida) in a Slight Risk for flash flooding throughout the day and into the overnight. A Slight Risk of flash flooding also exists for portions of the Southern Appalachians, where widespread rains will interact with terrain to create potential problems. The cold front will pick up some speed but weaken a bit as the surface low starts to lift northeastward. It will traverse eastward across much of the Southeast this evening and overnight, before reaching the Atlantic Coast by early Tuesday afternoon. The surface low will be a bit slower to exit, remaining across the Northeast through Wednesday before finally shifting off the coast. Continued rain and thunderstorms will proceed the passage of the cold front, spreading northward and westward around the area of low pressure, impacting much of the eastern U.S. today through Tuesday. Strongest storms are expected to remain near and along the Gulf Coast. Once the cold front is east of the Appalachians by Tuesday morning, the severe weather and flash flooding will no longer be threats. Much of the Northeast will once again find themselves in the cold sector of the system, with precipitation falling as a mixture of rain, snow, and ice beginning early Tuesday morning and continuing through Wednesday. Winter Storm Watches have been posted for portions of southern Maine and eastern Delaware as a result. Another cold front will continue dropping southeast from the Intermountain West today, traversing portions of the Southwest and Southern Rockies, and shifting into the western extent of the Southern Plains by tonight. Along this frontal passage, showers and thunderstorms can be expected today, with some lingering rain and higher elevation snow expected behind. By tonight, all precipitation should change to snow, impacting portions of the Rockies, Northern Plains, and Central Great Basins through Tuesday, before tapering off Tuesday night. Winter Storm Warnings and Winter Weather Advisories are currently in effect for the highest elevations in the Central Rockies, where snowfall in excess of a foot is possible. The cold front will continue on a eastward track from Tuesday into Wednesday, once again bringing the chance for showers and thunderstorms across portions of the Southern and Central Plains, eastward into the Mississippi River Valley and along much of the Gulf Coast. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php