Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 403 PM EDT Thu Oct 27 2022 Valid 00Z Fri Oct 28 2022 - 00Z Mon Oct 31 2022 ...Central and Southern Rockies... Day 1... High elevation snow associated with an upper low dropping southeast across New Mexico from the Four Corners region will continue to impact portions of southeastern Colorado and New Mexico into the evening hours. While widespread heavy accumulations are not expected, there is the potential for locally heavy amounts, especially across portions of the Sangre de Cristo Mountains and the Raton Mesa. WPC PWPF shows some small areas with probabilities exceeding 30 percent for additional accumulations of 4 inches or more this evening. Snows are expected to diminish as the low moves east into West Texas overnight. ...Pacific Northwest... Day 1 and 3... Confluent and moist mid-level flow will continue impact the region, with an embedded shortwave forecast to move onshore by early tomorrow. A brief surge of warm air advection ahead of this shortwave trough will produce moderate ascent into a moistening column. Snow levels will be high at the onset (around 6000 ft). Above this level, there is the potential for significant snow accumulations, with WPC probabilities for accumulations of more than 4 inches reaching above 50 percent in some locations. However, these higher probabilities are generally just for the far northern Washington Cascades, and above pass level. Drier conditions and high snow levels will preclude the threat for any significant winter weather impacts on Day 2. On Sunday, strong westerly flow ahead of an amplifying trough over the northern Pacific will begin to focus farther south, bringing the next round of precipitation into western Washington, including mountain snows. Snow levels are expected to remain high through Sunday, limiting the threat for heavy accumulations to the higher elevations of the northern Washington Cascades. The probability of significant icing is less than 10 percent nationwide. Pereira