Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 258 PM EST Wed Dec 11 2019 Valid 00Z Thu Dec 12 2019 - 00Z Sat Dec 14 2019 ...Heavy snow in the mountains of the Pacific Northwest and northern/central Rockies... ...Periods of snow over to develop over the Upper Midwest and northern Great Lakes Thursday... ...Widespread showers across the Southeast, potentially icy conditions in the southern Appalachians on Friday... A stream of Pacific moisture will allow for widespread showers and mountain snow to overtake the Northwest tonight and into Thursday. From the Cascades to the northern and central Rockies, snow accumulations in excess of a foot are expected with some of the higher elevations receiving well over a foot. In preparation for this heavy snow event, Winter Storm Warnings have been issued for the Cascades and northern Idaho and Winter Storm Watches have been posted for parts of central Idaho, northern Utah, and western and southern Wyoming. The Northwest will not be the only region to receive snowfall the next couple days. Snow over North Dakota tonight will head for the Upper Midwest Thursday morning as a weak disturbance tracks towards the Great Lakes. Snow will then reach the northern Great Lakes where some locations have already picked up heavy snow amounts from lake effect snow squalls earlier in the week. Winter Weather Advisories have been posted for areas where 3-6" of snowfall accumulation is anticipated. Snow will taper off as the disturbance heads northeast into eastern Ontario Friday morning. Further south, an area of low pressure in the Gulf of Mexico tomorrow will lift north and east on Friday. A combination of Atlantic and Gulf of Mexico moisture will engulf the Southeast, causing showers to develop Thursday and become widespread by Friday. Freezing rain and drizzle is also possible in the southern Appalachians as moisture overruns sub-freezing temperatures Friday morning. Icy conditions in these areas are possible but eventually, warmer temperatures will overspread the region and force a changeover to rain later in the day. Showers will race north in time for the Friday evening rush hour in the Mid-Atlantic, setting the stage for what will be a wet and cloudy Saturday in the Northeast. Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php