Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 232 AM EST Fri Jan 06 2017 Valid 12Z Fri Jan 06 2017 - 12Z Sun Jan 08 2017 ...Winter storm expected to bring potentially heavy snow from portions of the Southeast to the southern Mid-Atlantic... ...Heavy rain and mountain snow expected for central and northern California... ...Winter storm expected to bring snow and ice accumulations to portions of the Pacific Northwest... A developing low pressure system in the northern Gulf of Mexico is expected to bring a range of precipitation types from the lower Mississippi valley to the southern Mid-Atlantic region today into Saturday. A cold air mass in place will allow for a snow to fall today from portions of the southern plains and lower Mississippi valley east to the foothills of the southern Appalachians and the Piedmont of the Carolinas. Tonight, snow is expected to spread north across portions of the southern Mid-Atlantic region. Heavy snow is possible for some areas. Sleet or freezing rain is also possible in the transition zone from snow to rain across portions of the Southeast. Please refer to products issued by local NWS forecast offices for details specific to your area. As this low pressure system moves away from the East Coast into the north Atlantic by Saturday afternoon, cold air is expected to linger across areas from the southern plains to the Mid-Atlantic, with afternoon high temperatures 10 to 20 degrees below average. The western U.S. will start off the forecast period relatively quiet, with high pressure keeping most areas dry. By late Friday night into early Saturday morning, however, a Pacific frontal system will rapidly spread moisture back into the West Coast. Widespread and potentially heavy rain is expected for much of central and northern California, with heavy snow in the mountains. Farther north, cold air in place across the Northwest will create the potential for snow and ice accumulations across much of Oregon and Washington. Rain and snow will continue for the West Coast Saturday night and Sunday, with precipitation also spreading into the Great Basin, northern Intermountain West, and portions of the northern Rockies. Along the West Coast, snow levels will gradually rise, with all but the highest elevations of the Sierras changing to rain by Sunday morning. Lingering cold air in the interior valleys of Oregon and Washington will continue the potential for snow and freezing rain for those areas. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php