Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EST Fri Jan 19 2024 Valid 12Z Fri Jan 19 2024 - 12Z Sun Jan 21 2024 ...Another arctic air intrusion spreading into much of the central to eastern U.S.... ...Heavy precipitation moving into much of California for the weekend with heavy snow along the Sierra Nevada... ...Significant icing possible today and early Sunday through the Columbia River Gorge in the Pacific Northwest... ...Accumulating snows spreading from the Midwest into the Mid-Atlantic... ...Lake-effect snows remain active into Saturday... Another surge of arctic air is currently in progress across the mid-section of the country and then overspread the entire eastern U.S. by this weekend. While not as cold as the previous arctic outbreak that produced numerous records across the Plains and lower Mississippi Valley last week, this latest arctic blast will result in sub-zero temperatures as far south as Missouri and Kansas by Saturday morning, while wind chill temperatures as low as -20 to -30 will be common through Sunday morning. Ahead of the arctic surge, widespread light snow associated with an Alberta Clipper has already overspread the Midwest, Ohio Valley, and into the central Appalachians early this Friday morning. Meanwhile, a low pressure system is beginning to form just off the coast of the southeastern U.S. This system is forecast to intensify rapidly as it races off the East Coast tonight. The speed of the East Coast low will not allow much chance for the Alberta Clipper to tap into its energy source. Nevertheless, widespread accumulating snows associated with the clipper are expected to quickly move into the Mid-Atlantic and southern New England coastal section today and into this evening as the snow tapers off across the Ohio Valley. Snowfall totals are expected to be in the light to moderate range, generally 2 to 4 inches, with some locally heavier totals over 6 inches in the wind-facing slopes of the central Appalachians from eastern Kentucky/Southwest Virginia into West Virginia. Portions of the northern Mid-Atlantic are forecast to receive amounts in the 4 to 6 inches range while the vicinity of Cape Cod may also receive higher amounts due to possible enhancing effects from the ocean waters. As the arctic air moves over the Great Lakes, lake effect snow showers will be increasingly widespread downwind of the Upper Lakes today, and then into the lower Great Lakes by Saturday. Locally heavy snows are likely across portions of the upper peninsula of Michigan, the western portions of the lower peninsula of Michigan, across northwest Indiana and from northeast Ohio, across far northwest Pennsylvania into portions of western New York State. While the central to eastern U.S. will be entrenched in much below average arctic air, much of the western U.S. from the Rockies to the West Coast will see above average temperatures over the next few days. In addition, the next in the recent series of storms to move off the Pacific will bring heavy precipitation into large portions of California beginning this afternoon and continuing through the weekend and into early next week. The exception to above average temperatures across the West will be over the interior Pacific Northwest from north central to northeast Oregon into Washington State to the east of the Cascades. The western extent of the arctic air over the Northern Plains will remain in place across these regions. This will support potential for very dangerous icing conditions through the Columbia River Gorge today before a lull expected to set in this evening. However, the next surge of moisture from the next Pacific system will likely overspread northern California with heavy rain Friday night into Saturday. Heavy snow will then reach the Sierra Nevada Saturday night. Scattered mixed precipitation will penetrate farther inland into the Intermountain region by Sunday morning as more freezing rain could impact the Columbia River Gorge once again. Kong/Oravec Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php