Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 321 PM EDT Thu Mar 14 2024 Valid 00Z Fri Mar 15 2024 - 00Z Mon Mar 18 2024 ...Central Rockies, Southern Rockies, and the Southwest... Days 1-3... ***Significant and long lasting winter storm to produce heavy snow across much of the terrain of the central and southern Rockies, and Four Corners region.*** As deep upslope flow continues, a new surge of deeper moisture will fuel the return of heavy snow to portions of the Colorado Front Range and Foothills, where localized snowfall rates of 1-2 in/hr are expected to continue into the evening hours. The threat for heavy snow will likely begin to wane as the low-to-mid level flow becomes more southerly on Friday. WPC PWPF shows high probabilities (greater than 70 percent) for additional amounts of 8 inches or more for portions of the Front Range and Foothills, where storm totals of 2-4 ft will be common. Meanwhile, the heavy snow that has developed further to the south across southeastern Colorado earlier today is expected diminish by this evening. However, increasing moisture advection into a low- to-mid level boundary settling south of the Colorado-New Mexico border will rejuvenate the threat for heavy snow tonight into early Friday along the Sangre de Cristos, spreading south from southeastern Colorado into northeastern New Mexico. There too, WPC PWPF shows high probabilities for additional amounts of 8 inches or more. Snow is expected to diminish as winds become more southerly by late Friday. Heavy snow will also develop tonight closer to an anomalously deep upper low that is now settling south into the lower Colorado Basin. The position of the low along with deep moisture advection will favor heavy, high-elevation snow for portions of the Four Corners region. These areas include the southern Utah mountains, the Kaibab Plateau, Mogollon Rim and White White Mountains in Arizona, the northeastern New Mexico mountains, and the San Juans. For the Day 1 period (ending 00Z Sat), WPC PWPF shows at least moderate probabilities (greater than 40 percent) for amounts of 8 inches or more for parts of these areas, with high probabilities for a foot or more across portions of the southern Utah and the San Juans. Snow will continue across portions of the region as the upper low lingers along the California-Nevada border through Saturday. Additional heavy accumulations are expected, especially for portions of the southern Utah mountains and the San Juans where storm totals are likely to exceed 2 feet in some locations. Areas of snow will likely continue into Sunday, but with a diminishing threat west of the Four Corners as the upper low shifts slightly east. While far from certain, portions of the San Juans and southern Sangre de Cristos may see additional heavy amounts during the Day 3 period (ending 00Z Monday). The probability of receiving at least 0.1" ice is less than 10% across the CONUS through Day 3. Pereira **Key Messages for the March 13-16 Winter Storm can be found on our website at https://www.wpc.ncep.noaa.gov**