Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 339 AM EST Sun Jan 26 2020 Valid 12Z Sun Jan 26 2020 - 12Z Wed Jan 29 2020 ...Northwestern CONUS... Days 1-3... In a series of progressive shortwaves to impact the Pacific Northwest, snowfall accumulations are expected to primarily affect higher elevations of northern CA, western OR, and western WA with the highest probabilities of heavier snow totals across the WA Cascades due to relatively high snow levels elsewhere. # day totals a couple of feet are expected in the WA Cascades. The highest amounts today/tonight are forecast to be in the WA Cascades due to the longer duration of overlapping lift/moisture. Another surge of moisture and lift associated with the upper level jet maxima and low level warm advection is expected to produce another round of locally heavy snow in the northern OR Cascades and WA Cascades Monday/Mon night. A break looks to develop on Day 3 in the WA Cascades as the upper trough moves onshore and inland, with drying aloft developing in its wake. Across portions of central/northern ID and northwest MT, several inches are snow are expected as the repeating shortwaves track through the central/northern Rockies. While no particular system is likely to produce widespread heavy snowfall, the cumulative affect over the next 3 days will produce considerable accumulations for the highest elevations. The combined moisture transport and lift extends inland into the Blue Mountains of northeast OR. The 3 day total show potential for a foot across the ranges of northeast OR to southern ID and northwest WY. Lighter snowfall totals will spread southeast across areas with upslope flow in the Great Basin and CO/NM. Snow should taper Tuesday morning as the upper trough departs and moves east onto the Plains. ...Lower Great Lakes/New York/northern New England... Days 1-3... An area of low pressure move north from Maine into New Brunswick later today. The strong low to mid level warm advection ahead of the low has resulted in freezing rain and drizzle over interior portions of eastern Maine. This is expected to continue into the morning hours and then fade during the afternoon, along with reduced precipitation rates. Because of the short duration, amounts will be on the lighter side today. Strong cyclonic flow in the wake of the departing system will bring a prolonged period of enhanced moisture and lift across both Lake Erie and Lake Ontario. Aided by the favorable west/southwest flow and enhancement due to topography, several inches of snow are expected in the lee of both lakes across southwest and upstate New York. On Monday, amounts are lighter as a progressive front crosses the lower lakes, with lighter snow amounts following shorter cross lake trajectories and weaker lift. Most locations on Monday are forecast to get an inch or two, with no heavy snow areas identified. ...Southern Plains... Day 3... The models show a 700 mb wave progressing across southeastern CO and NM and then into the OK/TX panhandles by Tue morning, continuing east across OK into AR later Tue. Light mixed precip is forecast along the path of the wave, with the exception of the 00z ECMWF, which showed potential for several inches of snow in the TX/OK panhandles, due to a strong 700 mb wave. The probabilities for mixed freezing/frozen precip decline as the wave moves into relatively warmer air in the lower MS Valley. The probability of 0.25 inches of freezing rain is less than 10 percent Days 1-3. Petersen