Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 256 PM EST Sat Dec 21 2024 Valid 00Z Sun Dec 22 2024 - 00Z Tue Dec 24 2024 ....Light to moderate snow, with locally higher amounts, will develop over parts of the Great Lakes; Light to moderate snow over the higher elevations across the West... ...Light rain/freezing rain over parts of the Northern High Plain on Saturday evening into Sunday; Light patchy rain/freezing rain over parts of the Upper Mississippi Valley/Great Lakes on Sunday evening into Monday... ...Temperatures will be 10 to 20 degrees below average over the Northeast and Mid-Atlantic... Upper-level troughing and upper-level energy will create lake-effect snow downwind from the Great Lakes and upslope snow over parts of New England through Sunday morning. Furthermore, high pressure over the Great Lakes on Saturday will move eastward to off the New England Coast by Monday. The high pressure will bring temperatures 10 to 20 degrees below average over the Northeast and Mid-Atlantic. In addition, upper-level energy over the Northwest will move eastward to the Great Lakes by Monday evening. Weak onshore flow associated with the energy will produce light coastal rain and higher-elevation snow over parts of the Pacific Northwest and Northern/Central California through Sunday morning. As the energy moves farther eastward, light snow will develop over parts of the Northern Rockies late Saturday evening into Sunday morning. On Sunday afternoon, a front over the Eastern Pacific will move into the West Coast and dissipate. Moisture associated with the boundary will produce light rain over parts of the Pacific Northwest and Northern California overnight Sunday into Monday. Meanwhile, a wave of low pressure over the Northern High Plains on Saturday will move eastward to the Great Lakes by Monday evening. The system will produce light snow over parts of the Northern Plains on Sunday afternoon into evening. Along the rain/snow line, areas of light rain/freezing rain will develop over parts of the region through Sunday night. On Monday, as the storm moves into the Great Lakes, light to moderate snow will develop over parts of the Great Lakes. The snow will be more moderate along the northeast coastline of the Lower Peninsula of Michigan and the south coast of the Upper Peninsula of Michigan. Rain will also develop over parts of the Ohio, Middle/Lower Mississippi Valleys, and Southern Plains by Monday evening. Further, along the rain/snow line, pockets of rain/freezing rain will develop over parts of the Great Lakes and Upper Mississippi Valley. Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php