Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 325 PM EST Thu Jan 21 2021 Valid 00Z Fri Jan 22 2021 - 00Z Sun Jan 24 2021 ...Heavy snow for the Sierra Nevada Mountains, mountains of the Great Basin, and the Central Rockies Friday through Saturday... ...Heavy lake effect snow downwind from Lakes Erie and Ontario through Friday... ...Snow to develop over parts of the Upper Midwest Saturday... A front extending across the interior Gulf Coast States will have moisture pooling along the boundary and will produce rain from parts of the Southern Plains eastward across the Southeast through Friday. Meanwhile, a reinforcing cold front will sweep across the Great Lakes tonight, producing favorable cold westerly to northwesterly flow across the unfrozen Great Lakes. Lake-effect snow showers will increase in coverage and intensity this evening and continue through Friday. Locally-heavy snow accumulations are likely with the heaviest totals expected over western and northwestern portions of New York State, downwind from Lakes Erie and Ontario; northern portions of the Lower Peninsula of Michigan, downwind of Lake Michigan; and along the north coast of the Upper Peninsula of Michigan, downwind of Lake Superior through Saturday. A front over the Pacific Northwest will advance southeastward to the Southwest through Friday and into the Southern Rockies Saturday. The system will produce coastal rain and higher elevation snow over parts of southern Oregon through California and snow across the Intermountain Region into parts of the Northern Rockies through Friday. Later Friday, higher elevation snow will develop over parts of Northern/Central California. The higher elevation snow will expand across the terrain of the Great Basin, Southwest, and Central/Southern Rockies along with lower elevation rain. The rain will also shift into Southern California on Friday evening. By Saturday morning, the rain and snow will end over the Pacific Northwest and most of Northern California, yet continue over Southern California, the Sierra Nevada Mountains, and the Great Basin into the Central/Southern Rockies. Overnight Friday through Saturday, a front over South-Central Canada will move southward into the Upper Midwest. In conjunction with upper-level dynamics over the Central/Southern Rockies, snow will develop over parts of the Northern/Central Plains into parts of the Upper/Middle Mississippi Valley. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php