Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EST Sun Dec 24 2017 Valid 12Z Sun Dec 24 2017 - 12Z Tue Dec 26 2017 ...Heavy snow possible over parts of the Northeast and the Upper Great Lakes... ...Snow possible for part of the Cascades and the Northern/Central Rockies... ...Snow, rain, and freezing rain mixed over parts of the Northeast... Rain is expected today for much of the coastal Southeast and Mid-Atlantic as an area of low pressure develops along the cold front moving offshore over the Atlantic Ocean. Much of the Ohio Valley, Upper Midwest, Great Lakes and the Northeast will have snow as post frontal cold air surges in and a clipper system advances through the northern-tier states. Snow will spread from the Northern/Central Rockies across the High Plains and through the Great Lakes and Northeast. A few locations will be in the transition zone at the juncture of the two air masses, resulting in mixed precipitation- this will likely occur over a section of the eastern Ohio Valley/Central Appalachians, however, it is expected to change over to snow by early Christmas morning. Snow will be heavy at times, especially for the favored areas downwind of the Lakes and for upslope areas of Upstate New York to western Maine. Snow covered roads across this region may be lead to hazardous conditions - travelers are urged to allow extra time to arrive safely. Rain and higher elevation snow will spread from the Pacific Northwest Coast to the northern fringe of the Great Basin and the Northern/Central Rockies as a low pressure system moves onshore from the Pacific Ocean. Although the system is forecast to dissipate by Christmas afternoon, precipitation will continue into Tuesday. Snow will be heavy at times for the Cascades, Northern Rockies and Central Rockies. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php