Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 434 AM EDT Sat Mar 16 2024 Valid 12Z Sat Mar 16 2024 - 12Z Tue Mar 19 2024 ...Four Corners States... Days 1-2... Mid-upper level low becomes increasingly cutoff and stalled today over the lower Colorado Valley as a ridge further focuses over BC/WA. Confluent low level flow east of this low will continue to allow moisture and moderate to heavy precipitation across the southern Rockies into Sunday. Snow levels of 7000-8000 ft will continue over the San Juans and Sangre de Cristos before dropping to around 6500 ft tonight as the low wobbles east where Day 1 PWPF high for >8". As the upper low begins to fill in place Sunday, surface high pressure shifting south down the Plains shifts the focus for precip over central NM with snow levels remaining around 6500ft. Day 2 PWPF for >8" are moderate over the southern Sangre de Cristos over to the San Mateo Mtns. Low pressure lingers over AZ probably through Tuesday, but the moisture focus shunts farther south as the surface high plunges down the Plains that by Monday morning. only lighter precip is expected over southern NM/AZ. Key Messages remain in effect for this system which are linked below. ...Great Lakes and New England... Days 1-3... Potent shortwave trough digging through Ontario today will shift east over northern Maine Sunday night. The associated cold front will spread over the region through tonight with 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 where Day 1.5 PWPF for >4" are 40-80%. The focus shifts to the eastern Great Lakes Monday with Day 3 PWPF for >4" 40-70% above Erie, PA, along the Chautauqua Ridge, and Tug Hill Plateau. The probability of receiving at least 0.1" ice is less than 10% across the CONUS through Day 3. Jackson **Key Messages for the March 13-16 Winter Storm can be found on our website under "WPC Top Stories": https://www.wpc.ncep.noaa.gov