Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 309 AM EST Fri Nov 25 2022 Valid 12Z Fri Nov 25 2022 - 12Z Mon Nov 28 2022 ...New Mexico to West Texas... Day 1.. An anomalously deep closed low will continue to settle south from southern New Mexico and West Texas into northern Mexico this morning before slowly lifting back to the northeast across the Big Bend Region tonight into early tomorrow. Overall, the overnight guidance has remained consistent -- signaling that heavy snow amounts are likely for portions of southeastern New Mexico and West Texas, especially along the eastern slopes of the Guadalupe and Davis mountains. Broad scale ascent afforded in part by left-exit region upper jet forcing along with upslope flow is likely to bolster amounts in this region. WPC PWPF shows moderate to high probabilities for accumulations of 6 inches or more for this area during the day today. Meanwhile, snow along the western edge of a slow-moving deformation band is expected to produce some locally heavy amounts across portions of the southeastern New Mexico plains as well. WPC PWPF is indicating some moderate probabilities for accumulations of 6 inches or more across that also. ...Pacific Northwest and northern Rockies... Days 2-3... Heavy mountain snow is expected to return to the Olympics and northern Cascades by the latter half of the weekend. Deep onshore flow and large-scale ascent ahead of a well-defined shortwave diving southeast from the Gulf of Alaska is expected to bring widespread precipitation into the region by Sunday. Lower snow levels will support accumulating snows at the Cascade passes, with WPC PWPF indicating moderate to high probabilities for accumulations of 4 inches or more at both Snoqualmie and Stevens passes on Sunday. This initial wave is forecast to move east across the northern Rockies by late Sunday and into Plains by early Monday. This will carry the potential for locally heavy mountain snows farther east, with WPC PWPF indicating moderate to high probabilities for accumulations of 6 inches or more across the higher elevations of the Blues, as well as the northern and central Idaho, northwestern Montana, and the northwestern Wyoming ranges. This leading wave will be quickly followed by a second wave diving southeast which will bring additional precipitation and a reinforcing shot of colder air into the Northwest. This second wave is expected to gradually spread organized, heavier precipitation south along the Washington into the Oregon Cascades Sunday night into Monday. Across Washington and northern to central Oregon, accumulating snow is likely fall well below all pass levels, with snow levels dipping below 1000 ft across Washington by early Monday. By early Monday, WPC PWPF shows moderate to high probabilities for accumulations of 6 inches or more across most of the Washington and northern to central Oregon Cascade passes. The probability of significant icing exceeding 0.1 inch is less than 10%. Pereira