Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 258 AM EST Tue Dec 26 2017 Valid 12Z Tue Dec 26 2017 - 12Z Thu Dec 28 2017 ...Freezing rain possible over parts of the Pacific Northwest... ...Expect snow across the Cascades and northern Rockies... ...Great Lakes to experience lake effect snow... A wavy, stalled front draped from the Pacific Northwest to the Central Rockies has generated coastal rain and mountain snow; which will persist through midweek, especially as another system approaches from the Pacific. Freezing rain will be possible in some of the valleys of Washington and Oregon today and on Wednesday as warmer air lifts into the region. Higher snow accumulations is expected for northern Idaho and western Wyoming. Canadian high pressure will continue to slide southeast into the Dakotas/Upper Mississippi Valley and into the central U.S. over the next few days... keeping frigid air in place. A vast portion of the northern-tier states have Wind Chill Advisories and Warnings in effect. Further east, the westerly flow moving across the Great lakes region combined with the influx of cold air, heavy lake effect snow is expected for the favored areas downwind of the lakes. This setup is forecast to persist, as such, lake effect snow warnings are in effect for parts of the Great Lakes. See WPC's winter weather products for more detail. Much of the South/Gulf states will have showers through at least Thursday as warm, moist air lifts from the Gulf of Mexico. A transition zone may set up from the Lower Mississippi Valley to the southern Tennessee Valley/Appalachians as a cold front sinks through the Central Plains, Midwest and Tennessee Valley. A narrow swath of freezing rain and/or mixed precipitation may materialize from southern Arkansas to southern North Carolina as the two air masses collide. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php