Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 411 PM EST Sat Dec 23 2017 Valid 00Z Sun Dec 24 2017 - 00Z 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... Low pressure over Northern New England will move northeastward into the Canadian Maritimes by Sunday morning, Christmas Eve, while an area of low develops over the Southeast. Snow, rain, and freezing rain, mixed will develop over parts of Northern New England on Saturday evening that will change over to areas of rain and snow overnight Saturday. These areas of rain/snow will come to an end over the Northeast by Sunday morning. Snow will also develop over parts of the Lower Great Lakes/Eastern Ohio Valley that will wane by late Saturday night. In addition, rain will develop over Southern New England into the Northern Mid-Atlantic that will, likewise, end by Sunday morning. Rain and a few embedded thunderstorms will develop along the associated front over parts of the Southern Mid-Atlantic/Southeast that will move off the coast Sunday afternoon into Sunday evening on Christmas Eve. Meanwhile, upper-level energy over the Northern Rockies will move southeastward to the Southern Ohio Valley by Sunday evening that will begin to move off the Northeast Coast by Christmas morning, Monday morning. The energy will aid in developing low pressure over the Ohio Valley by Sunday afternoon into evening that will merge with a wave of low pressure over the Southeast forming a deep low over the Gulf of Maine on Christmas morning, Monday morning. The energy will aid in producing snow over parts of the Central Rockies/Central Plains that will move into the Central Plains/Middle Mississippi Valley by Sunday morning that in turn will expand into the Great Lakes and Ohio/Tennessee Valleys by Sunday evening. The snow will move into the Northeast by Christmas morning, Monday, with the snow heavy at times. Additionally, rain will begin to develop over parts of the Tennessee Valley Sunday afternoon that will expand into the Central Appalachians by Sunday evening. The rain will change over to snow over the Central Appalachians overnight Sunday. Also overnight Sunday, rain will develop over Northern Mid-Atlantic Coast moving into parts of Southern New England by Monday morning, Christmas. A front over South-Central Canada will move southward to the Great Lakes to Central Plains/Central High Plains by Christmas morning, Monday. Snow will develop along the front from the Upper Great Lakes to parts of the Northern High Plains that will taper off to to lake effect snow over the Upper Great Lakes by Monday morning, Christmas. Elsewhere, a front over the Eastern Pacific will move onshore over the Pacific Northwest that will dissipate over the Great Basin by Monday, Christmas. The system will produce rain and higher elevation snow over parts of the Pacific Northwest on Sunday afternoon that will expand into the Northern/Central Rockies as snow overnight Sunday into Monday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php