Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 432 PM EDT Sun Oct 14 2018 Valid 00Z Mon Oct 15 2018 - 00Z Thu Oct 18 2018 Day 1... ...Southern Rockies into the Great Lakes... Positively tilted upper trough will dive into the Four Corners region through Monday with a northern stream upper low crossing north of the Great Lakes will continue localized snowfall particularly tonight. Wisconsin and the UP will be in the right entrance region of the northern stream jet tonight where a few inches are possible. The probability of significant icing (0.25 inch or more) is less than 10 percent. Day 2... ...Ranges of New Mexico, Colorado, and Arizona... A positively tilted trough across the southwest CONUS will close off over the Sonoran Desert Tuesday. 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 4 inches of snow in the high terrain of the Sacramento mountains and Mogollon Rim. ...Southwest Texas... Freezing rain is possible in the Davis and Guadalupe Mountains Tuesday morning as moist southwesterly flow overruns N/NE surface winds behind the cold front that moves through Monday. QPF is expected to be enhanced south of the developing jet over NM. Ice probabilities for a quarter inch reach 20 to 30 percent in these two mountain ranges. However, only a shallow sub-freezing layer is apparent in proximity soundings from the 12Z NAM/GFS around 800mb. Therefore only higher portions of these mountains are preferred for freezing rain at this time with around a tenth of an inch forecast for Day 2. Day 3... ...Mountains near the Four Corners... An upper-level low stalls over Arizona. E/SE winds around this feature will enhance column moisture and mountain snows are likely at high elevations. WPC probabilities are moderate for more than 6 inches of snow in the highest terrain of the San Juans. The probability of significant icing (0.25 inch or more) is less than 10 percent. Jackson