Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 329 PM EST Fri Dec 15 2017 Valid 00Z Sat Dec 16 2017 - 00Z Mon Dec 18 2017 ...Heavy snow possible over the Northern Cascades... ...Heavy lake effect snow possible downwind from Lakes Erie and Ontario... ...Snow possible over the Northern Rockies and parts of Southern New England Coast... Upper-level energy over Pensilvania will move eastward out over the Western Atlantic by Saturday morning. The energy will aid in producing light snow over parts of the Northern Mid-Atlantic Coast and Southern New England Coast that will end overnight Friday. In addition, another area of upper-level energy over Lakes Superior will, likewise, move eastward out over the Western Atlantic by Saturday evening. The energy will aid in producing lake effect snow downwind from the Great Lakes ending by Saturday evening. Additionally, a front over the Northern Plains into the Upper Great Lakes will also aid in developing light snow near the boundary that will lift northward into Western Ontario by late Saturday evening. Meanwhile, a strong upper-level trough moving onshore over the West Coast will move southeastward to the Northern Rockies/Southwest by Sunday. The energy will aid in producing coastal rain and higher elevation snow over the Pacific Northwest through Saturday morning. Overnight Friday, snow will develop over parts of the Northern Intermountain Region/Northern Rockies expanding into the Great Basin and streaming out into parts of the Northern/Central Plains on Saturday. The snow will begin to wane on Sunday morning over the area. A front will approach the Pacific Northwest Saturday afternoon into Sunday that will aid in producing coastal rain and higher elevation snow on Saturday afternoon into Sunday. Furthermore, as the upper-level energy moves into the Southwest on Saturday night into Sunday. Moisture from the Pacific will move into the Southwest that will aid in producing higher elevation snow and lower elevation rain overnight Saturday into Sunday. Elsewhere, an upper-level low over West-Central Mexican Coast will weaken and move northeastward into the Southern Plains/Lower Mississippi Valley by Sunday. Moisture from the Western Gulf of Mexico will start to flow northward over the Western Gulf Coast by early Saturday morning that will strengthen moving into the Lower/Middle Mississippi Valley and the Tennessee Valley by Sunday. Rain will develop over parts of the Western/Central Gulf Coast by Friday evening that will mostly come to an end overnight Friday. On Saturday as the moisture moves over the Southern Plains, rain will develop over Southern Texas that will expand and move northeastward into the Lower Mississippi Valley overnight Saturday into Sunday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php