Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 257 PM EST Fri Dec 20 2024 Valid 00Z Sat Dec 21 2024 - 00Z Mon Dec 23 2024 ...Snow will fall over parts of the Great Lakes, Central Appalachians, and Northeast... ...Record warmth possible across parts of the West Saturday,,, The general flow pattern favors an upper level trough across the eastern Pacific ocean, ridging aloft in the West, and troughing aloft in the eastern United States. The consequence of this pattern will be some rainfall along the West Coast, warmth across the Intermountain West, and cold across portions of the East. Starting out West, skirmishes of rain along the West Coast are expected both tonight and Saturday as low pressure systems move from the eastern Pacific first into Alaska then into western Canada. By Saturday, the second low moving into western Canada will push rainfall into the northern Intermountain West, and snowfall at higher elevations by Saturday afternoon and evening. On Sunday, a third low pressure system will arrive along the West Coast, bringing more rain showers and very high elevation snow to the region. High temperatures across northern portions of the West will rise into the 40s and 50s, high enough to threaten record high temperatures on Saturday. Across the Southwest, high temperatures should rise into the 70s and 80s, also threatening record high temperatures in and near southern Arizona. Mid-continent, a seasonably strong and cold high pressure system migrates from the Great Plains into the Great Lakes, bringing below average temperatures near and to its east. For some areas of the East, it should be the coldest temperatures thus far this winter. When combined with cyclonic flow around a pair of lows moving through the Midwest and offshore the East Coast, lake effect and lake enhanced snowfall is expected near the Ohio Valley, Great Lakes, portions of the Appalachians, northern Mid-Atlantic States, and New England through Saturday. Winter weather advisories are in effect for portions of Michigan and the Central/Southern Appalachians to advise further on the snow threat. Kebede/Roth Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php