Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM EST Sun Dec 23 2018 Valid 00Z Mon Dec 24 2018 - 00Z Wed Dec 26 2018 ...Heavy low elevation rain/mountain snow expected across western Oregon and northern/north-central California Christmas Eve... ...Moderate to heavy snow possible over the Sierra and central Great Basin on Christmas Day... ...Developing storm to bring potential travel trouble over the central U.S. beginning Wednesday... Unsettled weather is likely for much of the western third of the lower 48 over the next couple of days as a series of Pacific storm systems moves across the region. The first system currently pushing inland is weakening rather quickly, and will bring mostly light precipitation to the Pacific Northwest, northern California eastward into the northern Rockies through the remainder of today and tonight. Associated with this system, winter weather advisories are posted for the Cascades and sections of the northern Rockies. A much stronger system is expected to reach the coast on Christmas Eve and bring heavy low elevation rain and mountain snows to much of western Oregon southward through northern and north-central California. The heaviest snow totals...locally up to a foot or more...are expected over the southern Oregon Cascades, Shastas and northern/central Sierra from Monday through Monday night. This storm will continue to strengthen as moves into the southwestern U.S. by later Christmas Day. As a result, precipitation will spread southward through California and inland across the Great Basin...Southwest and southern Rockies during Christmas. Snow levels with this storm are fairly low, so aside from coastal areas and lower elevations in the Southwest, much of the precipitation will be in the form of snow. Heaviest snow will be over the central Sierra and higher terrain of the Great Basin, but should begin breaking out over the southern Rockies by Christmas night. During late Tuesday and Wednesday, this system will push out into the Rockies and High Plains and begin to tap some deep Gulf of Mexico moisture. As a result, heavy snow is likely for much of the southern/central Rockies northeastward into the northern and central Plains states, with potentially heavy rain and thunderstorms farther south through the southern Plains. This may result in some post-holiday travel difficulties during the middle of the week. Farther east, a quick-moving and relatively weak frontal system moving through the eastern U.S. will support rain showers over the central mid-Atlantic region, with light snow accumulations possible from the central Appalachians northward into New York and southern New England through Sunday evening and during the overnight hours. Meanwhile...another weak area of low pressure along an arctic boundary is likely to bring mostly light lake-enhanced snow showers through Christmas Eve to the upper peninsula of Michigan and northern lower Michigan. Later on Monday evening through Christmas day, a quick-moving weak upper level system will tap into a bit of returning Gulf of Mexico moisture to bring the chance for light rain showers to the middle and lower Mississippi Valley. Farther north across the upper Midwest, temperatures should be cold enough for a little light snow, but accumulations are expected to be light (in the 1-2 inch range). Klein Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php