Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 229 AM EST Sat Jan 07 2017 Valid 12Z Sat Jan 07 2017 - 12Z Mon Jan 09 2017 ...Heavy snow expected today and tonight from portions of the Southeast to the Mid-Atlantic and coastal New England... ...Frigid temperatures expected from the southern plains to the Mid-Atlantic region... ...Heavy rain and snow expected for much of the western U.S... A low pressure system will deepen off the coast of the Southeast and Mid-Atlantic states today, spreading wintry precipitation across a wide area from portions of Georgia and the Carolinas north to coastal New England. Snow and freezing rain will come to an end across most of the Southeast by midday. Snow will also fall across much of the Mid-Atlantic, gradually winding down during the afternoon. Snow is expected to continue across coastal New England into the early morning hours of Sunday before coming to an end. Heavy snow will be possible from portions of the Carolinas north to coastal portions of the Mid-Atlantic and the Northeast. Gusty winds as the low pressure deepens may also create blizzard conditions at times, primarily in areas close to the coast. Please refer to products issued by NWS local forecast offices for details specific to your area. In the wake of this storm system, frigid temperatures will persist through much of the weekend as an arctic air mass lingers. High temperatures today are forecast to be 15 to 30 degrees below average across a large area from the southern plains to the Southeast, Mid-Atlantic, and Ohio valley. Temperatures will moderate some across the southern plains on Sunday, but the cold air will persist on Sunday across much of the Southeast and Mid-Atlantic. Onshore flow and a series of Pacific frontal systems will continue an onslaught of precipitation across the western U.S. through the weekend. Heavy rain is possible across much of California, with flooding possible for some areas. Snow, potentially heavy, will fall over the Sierras and the Coastal Ranges and initially over the lower elevations of coastal Oregon and Washington. Snow levels will gradually rise through the day, with all but the highest elevations of the Sierras changing to rain by this evening. Cold air will remain trapped at some of the lower elevations near the coast in Oregon and Washington through early Sunday morning, keeping snow or freezing rain in place for some areas. Widespread snow, heavy for some areas, will also overspread much of the interior West through Sunday, including the Intermountain West and Great Basin as well as the central and northern Rockies. As warmer air Pacific air spreads inland, snow levels will also rise across these areas, with precipitation changing to rain across much of the Great Basin by Sunday night. As a cold front moves inland Sunday night, rain will once again change back to snow across interior portions of the Pacific Northwest. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php