Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 PM EST Wed Dec 21 2016 Valid 00Z Thu Dec 22 2016 - 00Z Sat Dec 24 2016 ...Heavy snow for the Sierras... ...Heavy snow for the San Juan Mountains... ...Heavy rain possible for parts of the Pacific Northwest/Northern California... ...Snow possible from parts of the Upper Mississippi Valley/Upper Great Lakes to Northern New England... Low pressure over the Great Lakes will move eastward off the Coast of Maine by Thursday evening. The system will produce snow over parts of the Upper Mississippi Valley/Upper Great Lakes on Wednesday evening that will move into the Lower Great Lakes/Northeast by Thursday morning. The snow will move off the Northeast Coast overnight Thursday. In addition, rain will develop over parts of Southern New England on Thursday ending by Thursday evening. Meanwhile, a weakening upper-level low off the West Coast of Mexico will move northeastward to the Central/Southern Rockies by Friday morning. Moisture from the Pacific will move into parts of the Southwest/Southern California through Thursday afternoon. The storm will produce showers and thunderstorms over parts of the Southwest/Southern California that will that will move into parts of the Southern Rockies by Thursday evening. Overnight Wednesday, snow will develop over parts of the Great Basin, Central/Southern Rockies and the Central High Plains that will expand into parts of the Central Plains/Middle Mississippi Valley by Friday morning. Rain will also develop over parts of the Southern Rockies on Thursday morning that will move into parts of the Southern High Plains by Thursday evening and expand into parts of the Southern Plains by Friday morning. Additionally, a front over the Pacific will begin to move onshore over parts of the Pacific Northwest overnight Thursday into Friday morning. Moisture ahead of the boundary will move into parts of the Pacific Northwest on Thursday producing rain along parts of the Northwest Coast Thursday afternoon and snow at higher elevations by Thursday evening. The precipitation will move farther inland over the Pacific Northwest/Northern California by Friday morning producing rain and higher elevation snow. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php