Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 332 PM EST Wed Feb 26 2020 Valid 00Z Thu Feb 27 2020 - 00Z Sun Mar 01 2020 Days 1-3... ...Northeast... As a mid-level shortwave moving through the Ohio valley begins to assume a negative tilt, surface low pressure will intensify quickly as it tracks north across western Pennsylvania and New York to Lake Ontario Wednesday evening. This will bring widespread rain advancing north and east across Pennsylvania and much of New York through the evening, with a rain/snow mix across the Adirondacks and Vermont, before changing over to snow across the higher terrain overnight. As the low lifts north into southern Ontario, a coastal low developing near Long Island and southern New England is expected to track north across southern New England to the northern New England coast on Thursday. Rain is expected across much of southern to central New England and along the Maine coast, with snow the dominate precipitation type across northern New Hampshire and interior Maine. Heavy snow accumulations are likely from the White Mountains into central and northern Maine, with WPC PWPF indicating accumulations of 8-inches or more likely across the higher terrain. Meanwhile, strong cold air advection and westerly flow on the backside of the primary system will set the stage for a prolonged heavy lake effect snow event east of Erie and Ontario. Heaviest amounts are expected to center across the Tug Hill region into the western Adirondack foothills. Guidance continues to present a strong signal band event beginning Thursday and continuing into Friday before winds begin to veer Friday evening. WPC PWPF indicates high probabilities for three day totals of 2-feet or more across the Tug Hill. Locally heavy snows are also possible east of Lake Erie in western New York and northwestern Pennsylvania. ...Central and Southern Appalachians... As the aforementioned low lifts out, temperatures are expected to quickly fall behind the trailing cold front -- supporting rain changing to snow along the central and southern Appalachians Wednesday night. A period of strong mid-to-upper level forcing along with orographic effects may support locally heavy totals from western Pennsylvania to southern West Virginia Wednesday night. Deep cyclonic flow with embedded mid-level energy will support additional snow showers on Friday into early Saturday, with additional light to moderate accumulations expected along the favored terrain. ...Pacific Northwest to the Northern Rockies... Organized precipitation/mountain snow is forecast to return to the region as a well-defined shortwave drops into the region Friday evening. By late Saturday, locally heavy snows of a foot or more are possible across the higher elevations of the Olympics and northern Cascades. Lighter totals are expected farther south along the Oregon Cascades and northern Rockies. For Days 1-3, the probability of significant icing (0.25-inch or more) is less than 10 percent. Pereira