Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 240 PM EST Sat Dec 22 2018 Valid 00Z Sun Dec 23 2018 - 00Z Tue Dec 25 2018 ...Unsettled weather can be expected with locally heavy rain for the coastal ranges of the Pacific Northwest and northern California over the next couple of days... ...Heavy snowfall is likely for the Cascades, northern Sierra-Nevada and the northern Rockies... In the wake of a deep low center exiting the Northeast, there will be a return to colder temperatures and at least some drier weather going through Sunday. However, the next storm system which will be crossing the northern Plains and upper Mississippi Valley will move east toward the lower Great Lakes by Sunday evening. The system will produce a swath of mainly light snow across parts of the upper Midwest and across the Great Lakes region through Sunday afternoon and evening. This will advance into the central Appalachians and parts of New York and southern New England on Christmas Eve. Some light rain meanwhile will impact portions of the Ohio and Tennessee Valleys as a cold front crosses the region. In the wake of this next system will be a surge of modestly colder air, but temperatures for much of the Eastern U.S. will be actually near or a bit above normal over the next few days since there will be a lack of cold high pressure dropping south from Canada. Much of the active weather going toward the Christmas holiday will actually be focused across the Western U.S. with an emphasis on the Pacific Northwest, northern California, and interior areas of the northern Great Basin and northern Rockies. A cold front will allow one surge of moisture to arrive overnight and through Sunday for the Pacific Northwest, with locally heavy rain for the coastal ranges and heavy accumulating snow over the higher terrain of the Cascades. This moisture and energy will reach the northern Rockies by Sunday evening. Meanwhile, on Christmas Eve, a wave of low pressure and associated front will be approaching coastal areas of Oregon and should bring a second surge of heavy rain to the coastal ranges, although this next axis of moisture and onshore flow will be focused farther south and should impact all of northern California. Heavy snow will be likely for the higher terrain of the northern Sierra-Nevada and gradually this snow will impact the higher terrain of the central and northern Rockies by late Christmas Eve. Elsewhere, the remainder of the country should see mainly dry weather and temperatures that are near or above normal. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php