Subj : Winter Storm Continues SW To : All From : Dumas Walker Date : Fri Mar 15 2024 09:10 am FOUS11 KWBC 150714 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 314 AM EDT Fri Mar 15 2024 Valid 12Z Fri Mar 15 2024 - 12Z Mon Mar 18 2024 ....Southern Rockies, Four Corners, and the Southwest... Days 1-3... ***Heavy snow wanes along the Front Range but continues across the Four Corners through the weekend*** The impressive snow event across the Front Range due to long- duration and robust upslope flow will begin to wind down today as the best ascent shifts southward, and mid-level flow begins to return to the south. This should bring a slow end to the upslope component of this event, although this will be at the expense of a larger scale event which begins in earnest across the Four Corners. Additional snow in the Front Range and Sangre de Cristos D1 only has a 30-60% chance of exceeding an additional 4 inches. Meanwhile, as precipitation across the Front Range begins to wane, the parent upper low sinking south towards the Desert Southwest will begin to exert its influence across the region. The deep low with height anomalies nearing -3 sigma according to NAEFS will spread pronounced and long-lasting mid-level divergence downstream from the lower CO Basin through the Central High Plains. Confluent flow southeast of this low will help surge moisture northward, combining with modest jet-level diffluence to expand moderate to heavy precipitation through Saturday. This will result in heavy snowfall in much of the terrain from the Mogollon Rim and Kaibab Plateau eastward into the Wasatch, San Juans, and Sangre de Cristos, with heavy snow accumulations likely above snow levels of 6000-8000 ft in the region of strongest WAA/heaviest precip, but may fall to 4000-5000 ft beneath the cold core low, especially as it begins to eject east by Sunday. WPC probabilities for more than 6 inches D1 are above 90% in the southern Wasatch and much of the San Juans, as well as the higher terrain of the Mogollon Rim, and White Mountains, with additional low to moderate probabilities (20-60%) fore 6+ additional inches on D2 across much of the same area. As the upper low finally begins to fill and eject eastward through the Four Corners on Sunday, total forcing for ascent and moisture should begin to wane. However, still sufficient moisture and persistent ascent both due to height falls and steepening lapse rates aloft will allow for precip falling as snow to continue to pivot eastward, primarily falling in the San Juans and Sangre de Cristos D3. Additional snowfall D3 is confined to the San Juans and Sangre de Cristos, where WPC probabilities for 6+ inches are again 20-40%. 3-day snowfall in some of the higher terrain of the Wasatch and San Juans will likely reach 2-3 feet. ....Great Lakes and New England... Day 3... A surface low pressure moving through Ontario and Quebec will drive a cold front through the Great Lakes, Ohio Valley, and into New England. Some modest moist advection will occur downstream and ahead of this front resulting in a narrow corridor of heavy precipitation lifting northeast into New England on Sunday. Much of this will likely fall as rain in the marginally favorable thermal structure of the column, but across northern NH and into northern ME, especially in higher elevations, WPC probabilities for more than 4 inches of snow are 10-30%. More impressive, although still somewhat modest, is likely to be an increase in lake effect snow (LES) behind the front as strong CAA surges southeast across the Great Lakes. This will result in axes of significant snowfall accumulations in the favored N/NW snow belts across the U.P. of MI, and along the Chautauqua Ridge and Tug Hill Plateau. WPC probabilities within the LES bands are as high as 20-30% downwind of Lakes Superior, Erie, and Ontario, highest across the U.P. of MI. The probability of receiving at least 0.1" ice is less than 10% across the CONUS through Day 3. Weiss **Key Messages for the March 13-16 Winter Storm can be found on our website at https://www.wpc.ncep.noaa.gov ** $$ --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175) .