Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 337 PM EST Wed Mar 06 2024 Valid 00Z Thu Mar 07 2024 - 00Z Sun Mar 10 2024 ...Southern California/Southwest... Day 1... An upper low shifts over SoCal this evening, reaching northern AZ Thursday. Expect moderate snow above about 6000ft snow levels in the peaks outside Los Angeles including around Big Bear Lake this evening and the southern Great Basin/Mogollon Rim and into the San Juans where there are localized values of Day 1 PWPF >6" in the 20-40% range. ...Central/Southern Rockies onto the Plains... Days 1-3... The upper low mentioned above opens into a trough/vort lobe over NM Thursday night as a reinforcing low pushes from SoCal to the northern Baja as a 150kt ESE jet streak lifts through West Texas. Surface weakness and marginal temperatures in the CO Plains will be met by an advancing cold front from the north as high pressure builds into the northern Plains from Canada. NE to E flow surface flow will help drive moisture into the region from the western Gulf, giving way to an upslope snow in the High Plains and adjacent eastern slopes of the Rockies. Moderate to heavy snow bands look to focus near the Raton Mesa/Sangre de Christos where Day 2 PWPF for 6" is 50-80%. As height falls reach the Plains (~100W), weaker areas of low pressure may form and lift northeastward, promoting bands of light to moderate snow on the northern side of the precipitation shield, generally from southeastern WY across southwestern Nebraska. There, Day 1.5 PWPF for >4" have increased to 20-40%. The surface ridge down the high Plains and the inverted trough up the eastern Plains/Mid-Mississippi Valley should allow further snow banding Friday morning over the OK/northern TX Panhandles where Day 2.5 PWPF for >4" is low, up to 10%, but with further CAM guidance coming into play soon, these probabilities should rise. ...Northern Plains... Day 1... Moderate snows near the northern ND/northwestern MN borders will continue to lift north into Manitoba through this evening. ...Northern New England... Day 1... Precip shield ahead of a southern stream low lifting up the Mid-Atlantic coast tonight and off New England Thursday expands over northern Maine where sufficient cold air infiltration from a 1035mb high over northern Quebec allows moderate to locally heavy bands to develop tonight into Thursday. A wintry mix is likely south of the snow over Down East Maine. Day 1 PWPF for >4" is 40-80% in a swath over northern Maine. Surface cold air drainage from the St. Lawrence Valley into northern NY overnight should allow pockets of freezing rain to develop on the northern side of the Adirondacks where Day 1 PWPF for >0.1" are 20-40%. ...Pacific Northwest... Day 3... The next trough approaches the PacNW Friday night with ample moisture and onshore flow bringing moderate to heavy snow in terrain above the near 4000ft snow levels for Olympics and the length of the Cascades to the Shasta/Siskiyou where Day 3 PWPF for >6" are 20-50%. Jackson