Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 439 AM EDT Mon Apr 04 2022 Valid 12Z Mon Apr 04 2022 - 12Z Thu Apr 07 2022 ...Northwest to the northern/central Rockies... Days 1-2... Strong, powerful, and elongated 170 kt jet will push into WA/OR today as a strong cold front moves through the region. Precipitable water surge will be short-lived in the progressive flow, peaking around +1 to +2.5 sigma today then dropping to below climo values Day 2. However, onshore flow will continue as a trailing mid-level vort max swings through Washington early Tuesday. Upslope will be robust into the Cascades where total amounts well over a foot will be common, including at some passes. Strong winds will create blowing snow and reduced visibility. Snow levels around 4000 ft this morning will drop to below 2000 ft this evening/overnight as much colder air moves in. Strong westerly flow will carry significant moisture east of the Cascades as well, focusing on the mountains in Idaho and western Montana as the front rapidly moves eastward today. Again, blowing snow will be common after the front passes; steep lapse rates will support squally snow showers after the main area of precip passes. Snow will spread into Wyoming by this afternoon where significant accumulations are also expected over the Tetons, Absarokas, and Wind River Ranges. Lighter snow will fall into Colorado by Day 2 with several inches in the higher terrain where snow levels will be much higher than in the Northwest. WPC probabilities for at least 12 inches of snow are high for elevations above around 2500 ft in the Cascades and are high for at least 6 inches of snow above around 5000 ft in Idaho/Montana and 5000-7000ft into Wyoming. ...Northern Plains/Upper Midwest/Western Great Lakes... Days 1-3... Weakening surface low this morning will spread generally light snow across Wisconsin into Lower Michigan with accumulations under a few inches, focused in the 12-18Z window. WPC probabilities for at least 4 inches of snow are less than 10 percent. On Day 2, western system will move through the High Plains as the mid-level vort digs into the Dakotas and closes off. Triple point low will take over as the main surface low on Tuesday as the system becomes stacked by Day 3, allowing moisture from the south to stream northward on the WCB. Temperatures will be marginal over much of the area except for toward the Canadian border and especially over the Arrowhead of Minnesota. Easterly flow will enhance lake-enduced convergence along the North Shore with upslope into the higher terrain where several inches of snow are possible Days 2-3. To the west, wobbling low centers will generally favor northwesterly flow into the Black Hills where upslope there will promote moderate snow totals on Day 3. WPC probabilities of at least 4 inches of snow are low to moderate over portions of the Arrowhead and moderate to high over the Black Hills. For Days 1-3, the probability of significant icing of at least 0.25" is less than 10 percent. Fracasso