Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 433 PM EDT Sun Mar 29 2020 Valid 00Z Mon Mar 30 2020 - 00Z Thu Apr 02 2020 ...Northeast... Days 1-2... A cold air damming wedge eroding north from the Mid-Atlantic as a warm front this afternoon will drift north toward southern New England tonight ahead of a weakening cold front associated with a low tracking across southern Ontario. A surface low will strengthen south of the New England coast tonight along the warm front which will help to drive elevated moisture across New England into Monday. The column will be cold enough for all snow across interior Maine and the White Mtns of NH where moderate precip rates can be expected. Day 1 WPC snow probabilities for six or more inches are moderate to high for northwestern Maine. A transition zone of a wintry mix spread southwest from the snow zone, mainly over terrain in VT and interior NH. Day 1 WPC ice probabilities are moderate for a tenth inch of ice on both the Green and White Mtns. The approaching upper low and persistent onshore low level flow will allow light precip as snow levels drop below 1000ft, but Day 2 snow probabilities are low for 2 or more inches over central Maine and NH. ...The West... Days 1-3... A cold core low will drift south from the eastern Gulf of Alaska to northern Vancouver Island through Monday before expanding across BC to Alberta through Tuesday. This strong cyclonic flow and shortwave impulses rounding this gyre and pushing into the Pacific Northwest coast will direct Pacific moisture across the northwestern CONUS. A cold front from this low will push ashore over WA/OR Monday with a swath of intensifying precip arriving to the coast tonight and slowly progressing across the rest of the Pacific Northwest and across the Northern Rockies through Tuesday before veering offshore flow reduces Pacific moisture influx through the midweek. Snow levels tonight are moderate ahead of the cold front, generally 3000 to 4000ft, before dropping to around 2000ft over WA Monday with a gradient around 4000ft along the cold front across OR to northern ID and far western MT before merely sagging southeast into Wednesday. The heaviest snow will be in the OR/WA Cascades and Olympics through Day 2 where the 48hr Day 1/2 probability for 18 or more inches is moderate to high with the highest terrain likely getting 2 to 3 feet. The next highest area is the Salmon River/Sawtooth Mtns of ID and Tetons in WY which are moderate for 18 inches through Day 2 and could see 2 feet. Otherwise the Day 3 probability for 6 inches is moderate to high across the northern Rockies and WA/northern OR Cascades and Olympics above 1500ft. For Days 1-3, the probability of significant icing (0.25-inch or greater) is less than 10 percent. Jackson