Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 413 AM EDT Sun Oct 14 2018 Valid 12Z Sun Oct 14 2018 - 12Z Wed Oct 17 2018 Day 1... ...Central Rockies into the Central Plains... Positively tilted upper trough will dive into the Four Corners region through tonight while a secondary impulse ejects northeast across the Southern Plains. Moisture confluence between these two features will ride atop a surface high pressure sinking southward behind a cold front. Although the best jet dynamics due to diffluence will shift away from the Central Plains, strengthening mid-level frontogenesis will drive increasing lift and precipitation today, with upslope enhancement also likely on the eastern slopes of the Rockies. In the terrain of Colorado and New Mexico, including the Sangre De Cristos and San Juans, WPC probabilities are high for more than 4 inches of snow, with more than 8 inches possible in the Sangre De Cristos. Across the Central Plains, a band of heavier snowfall is likely where robust snowfall rates will overcome otherwise marginal thermal profiles. There remains uncertainty into the exact placement of where this convective band may setup, but WPC probabilities are moderate for more than 4 inches of snow across north central Kansas. The probability of significant icing (0.25 inch or more) is less than 10 percent. Day 2... ...Ranges of New Mexico, Colorado, and Arizona... Shortwave digging into the mean positively tilted trough across the southwest will cutoff near Baja and become vertically stacked atop its 700mb reflection. Deep E/SE flow ahead of this feature will advect moisture pooled across Texas into the southwest, with some upslope enhancement likely. Total moisture is limited and the overall airmass is warm, but WPC probabilities indicate moderate probabilities for 2 inches of snow in the high terrain of the southern San Juans, Sangre De Cristos, and Mogollon Rim. ...Southwest Texas... Some light icing is possible as moist southerly flow overruns N/NE surface winds behind a cold front. QPF is expected to be light, with probabilities for more than one-tenth of an inch remaining very low. However, an upward trend has been noted and forecast soundings show a long duration of potential light freezing rain/freezing drizzle into day 3 across this area. At this time there are no probabilities for more 0.25 inches or more, but this will continue to be monitored for further upward trends. Day 3... ...Ranges of New Mexico and Arizona... Vertically stacked 700-500mb low will fill gradually while sitting nearly stationary over Arizona. E/SE winds around this feature will enhance column moisture and mountain snows are likely. WPC probabilities are moderate for more than 2 inches of snow, with 4 inches possible in the highest terrain of the Mogollon Rim and Sangre De Cristos. The probability of significant icing (0.25 inch or more) is less than 10 percent. Weiss