Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 459 PM EDT Sat Mar 15 2014 Valid 00Z Sun Mar 16 2014 - 00Z Tue Mar 18 2014 ...A threat for severe weather exists along the Gulf Coast states during the weekend... ...A late season winter storm should affect the Lower Ohio/Upper Tennessee Valleys and into the Mid-Atlantic... ...Heavy snow across the Pacific Northwest and Northern Rockies is expected... Upper energy currently organizing across the Southern High Plains has helped fuel an extensive area of showers and thunderstorms across Texas/Oklahoma this afternoon. As the system shifts its focus eastward, the threat for severe weather will continue as the air mass downstream will be rather moist and unstable. The Storm Prediction Center has highlighted an area from far east Texas along the Central/Eastern Gulf Coast states for an enhanced threat for severe thunderstorms through Monday morning. The progressive nature of the cold front should limit the threat for flash flooding this weekend while high pressure builds in behind bringing high temperatures down to the low 50s for Monday. While the action across the southern states will feature precipitation in liquid form, it will be quite the contrary for locations to the north from the Lower Ohio/Upper Tennessee Valleys eastward to the Mid-Atlantic and upper Carolinas. With a strong surface high settling across the Great Lakes region, northerly winds will sufficiently lower the temperatures over the region of interest. Much of the precipitation expected will occur in association with the upper disturbance affecting the southern U.S. The northern extent of this precipitation shield will be comprised of mixed precipitation before shifting to all snow as temperatures cool late Sunday night and into early Monday. In spite of the forecast being only 24 to 36 hours out, there still is uncertainty with the exact axis of snow, ice, and sleet. At this point, the WPC winter weather desk suggests the heaviest snowfall amounts will be over the Central Appalachians and extending eastward into the Mid-Atlantic/Delmarva Peninsula. Expected totals may range from 6 to 12 inches with the higher accumulations more into the higher terrain. South of the area of snowfall will be an extensive region of freezing rain which is forecast to extend from lower Missouri eastward into the Central/Southern Appalachians and Piedmont. For the latest information on the possible winter storm, please visit the WPC winter weather graphics on the WPC home page. With a large upper ridge anchoring the southwestern U.S., zonal flow above this dome of high pressure will allow a series of impulses to affect the Pacific Northwest and Northern Rockies the next couple of days. Initially it will mainly be a rain event across western Washington except for the higher elevations of the Cascades. As the flow begins to amplify offshore by late Sunday night, much colder air will work its way southward from western Canada which will quickly lower snow levels. Through Monday evening, expect the highest snow accumulations across the Washington Cascades where 1 to 2 feet will be possible. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php