Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 254 PM EST Sat Feb 03 2018 Valid 00Z Sun Feb 04 2018 - 00Z Tue Feb 06 2018 ...Heavy snow to blanket the interior northeastern U.S. with accumulating ice along the spine of the southern/central Appalachians... ...Abundant precipitation to fall over the Olympics, Washington Cascades, and Bitterroots... ...Ample warmth over the western states may break daily temperature records through Sunday... With modified Arctic air in place east of the Rockies, a wintry precipitation threat will exist with an evolving system across the eastern U.S. A strong upper trough sweeping through the Great Lakes on Sunday afternoon will be a focus for moderate to possibly locally heavy snow from the Great Lakes into interior New England. A widespread swath of 4 to 8 inches of snow is possible with forecast amounts somewhat limited by the progressive nature of the feature. Meanwhile, a separate threat for accumulating ice should be an issue for locations just west of I-95 back toward the spine of the southern/central Appalachian chain. Arctic air which has settled at the surface will likely be stubborn to be completely scoured out on Sunday. All the while, a plume of milder air will override this air mass leading to a freezing rain setup from extreme northeastern Georgia along along the Appalachians into north-central Pennsylvania. Farther south from the lower Mississippi Valley into the southeastern U.S., wet conditions will prevail as a frontal zone slides through the region. As a strong upper ridge sits over the coastal eastern Pacific waters, a series of impulses will traverse the northern extent of this anticyclone across the Pacific Northwest and into the upper Intermountain West. Vigorous lift from these impulses in conjunction with convergence along the stalled Arctic front will spread abundant precipitation from the Olympics and Washington Cascades eastward into the Bitterroots, Sawtooth, and Tetons. The heaviest amounts are forecast over the Washington Cascades with around 3 to 5 inches of precipitation expected through Monday. This is where some of the stronger upslope flow and better moisture profiles will reside. The air mass should be plenty cold enough to support widespread wintry precipitation over the region with 1 to 2 feet likely across western Montana down into northwestern Wyoming. Given the highly amplified upper-level pattern, temperatures should reside well away from climatology through the weekend. The coldest readings will remain fixed over the northern Rockies eastward through the Dakotas and into the Upper Midwest/Great Lakes. While highs struggle to get out of the single digits, the overnight low temperatures will plunge into the negative teens with a breeze making wind chills dangerously cold, possibly in the -20 to -40 Fahrenheit range. As such, the local offices over this region have a wind chill advisory in effect through roughly noon on Sunday. While this sector of the country is frigid, it will be quite the opposite over the western states. Persistent upper ridging will raise the mercury each day as highs surge into the 50s across the Pacific Northwest, 50s and 60s over the central Great Basin, and even some 80s into the Desert Southwest. As a result, there may be some daily temperature records broken this weekend, particularly for the warm overnight lows. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php