Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EST Sun Jan 31 2021 Valid 00Z Mon Feb 01 2021 - 00Z Wed Feb 03 2021 ...Major winter storm to produce significant snowfall across the Northeast tonight and into both Monday and Tuesday... ...There is a Slight Risk of excessive rainfall over parts of Northern California and southwest Oregon... An area of low pressure over the Ohio Valley is responsible for producing periods of snow in parts of the Lower Great Lakes and northern Mid-Atlantic. This low pressure system will pass the baton off to a new coastal storm forming near the Mid-Atlantic coast tonight. As the storm strengthens overnight and into Monday morning, bands of heavy snow look to set up over an area stretching from eastern Pennsylvania and the NYC metro area to southern New England. The coastal low will then stall just off the New Jersey coast and drop copious amounts of snow in these areas through the day Monday and even into Tuesday. The latest forecast for this long duration winter storm calls for over a foot of snow across a large portion of eastern Pennsylvania, northern New Jersey, southern New York, and into southern New England with totals over in excess of 20 inches in some locations. Gusty winds will help to reduce visibilities and lead to both blowing and drifting snow. Treacherous travel conditions are expected throughout the Northeast as the storm continues to generate periods of snow that stick around into the day on Tuesday. Snow finally begins to taper off for most areas by Tuesday night with the lone exception being northern New England where snow may continue into Wednesday morning. In the West, a Pacific storm system is triggering yet another atmospheric river event, sending more rainfall and mountain snow into the Pacific Northwest. A Slight Risk for excessive rainfall remains in place this evening along the coastal range of northern California and southwest Oregon. The frontal boundary near the coast inches its way east on Monday, pushing the axis of moderate-to-heavy rainfall into western Washington, Oregon, and northern California. A Marginal Risk for excessive rainfall has been issued for much of the same areas of northern California and southwest Oregon on Monday. Plenty of mountain snow is also on tap from the Shastas on north along the Cascade Range where the highest elevations could receive accumulations of 1 to 2 feet. By Tuesday, a new low pressure system associated with an upper level trough heads towards the Northwest. Showers and mountain snow are expected to persist across the Northwest with heavy snow falling in the northern Sierra Nevada where Winter Storm Watches are currently in effect through Tuesday night. Snow will also arrive in the mountains of northern Idaho and western Montana Tuesday night. Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php