Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 503 PM EDT Thu Apr 18 2013 Valid 00Z Fri Apr 19 2013 - 00Z Sun Apr 21 2013 ...Heavy snow...severe weather...and flooding rains will all be possible as a strong Spring storm heads towards the eastern third of the nation.... The Spring storm that brought heavy snows and flooding rain to portions of the central U.S. will begin impacting the eastern third of the nation during the short range period. Snow will continue to develop to the northwest of a deep surface cyclone tracking northeastward towards the Upper Great Lakes Thursday night into Friday...leading to a wide swath of late season snowfall accumulations across the Upper Midwest. Meanwhile...the potent trailing cold front will steadily march towards the Appalachians on Friday and off the Eastern Seaboard by Saturday morning. Deep Gulf moisture streaming northward ahead of the boundary will fuel an organized line of convection that could contain heavy downpours...damaging winds...large hail...or even tornadoes. Out west...precipitation will be on the increase over the northwestern corner of the country as a weak disturbance aloft moves inland. Precipitation totals will be light to moderate...with the heaviest amounts expected along the favored slopes of the terrain. However...temperatures will be low enough to support accumulating snows over the northern Rockies and Washington Cascades. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php