Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 415 AM EDT Wed Oct 16 2019 Valid 12Z Wed Oct 16 2019 - 12Z Sat Oct 19 2019 ...Pacific Northwest to the Northern Rockies... Days 1-3... Strong moisture transport occurs in a warm advection pattern across the Pacific Northwest today. Ahead of the trough, rising snow levels will confine significant accumulations to the higher peaks of the northern Cascades. By Wednesday evening, as the upper trough moves inland, snow elevations decrease to around 5000ft to provide greater coverage of snowfall. The heavier precipitation and resultant snow amounts occur on days 2-3 as the next 700 mb wave comes onshore Thu morning, bringing a surge in deep moisture and ascent to the Olympics and then WA Cascades. Strong and persistent lift 850-600 mb leads to long duration snows at higher elevations of the Cascades. A few feet of snow are possible at the higher elevations. On Friday, another round of heavy higher elevations now is expected with amplification of the succeeding 700 mb wave and resulting surge in moisture and ascent. This is supported by a band of strong 700 mb convergence Fri night to early Sat morning. 2-4 feet of snow is possible in higher elevations of the WA Cascades over a multi-day period. ...Northeast... Days 1-2... A powerful cyclone is expected to develop over the Mid-Atlantic coastal waters Wednesday and move into eastern New England while rapidly intensifying. Cold air is delayed until Thursday with sub-zero 850mb temps over interior New England, with snow levels gradually dropping Thursday. The higher elevations of the Adirondacks, Green and White Mountains have potential to change from rain to snow after the cold air arrives, with several inches possible due to slow movement of the upper low. Lower elevations are forecast to remain as mostly rain. ...Central Appalachians... Days 1-2... Northwest flow will support upslope precipitation into the central Appalachians Wednesday night into Thursday. Cold advection lower snow level enough so an inch or two of accumulating snow is expected across the higher peaks of the Alleghenies in West Virginia. The probability of significant icing is less than 10 percent Days 1-3. Petersen