FOUS11 KWBC 150653 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 253 AM EDT Wed Apr 15 2026 Valid 12Z Wed Apr 15 2026 - 12Z Sat Apr 18 2026 ...Cascades... Day 1... Strong upper low approaching Vancouver Island this morning will continue southeastward today, with a lead cold front moving through the WA Cascades. The heaviest snowfall will be just ahead of the cold front this morning from the southern WA Cascades into the OR Cascades. Snow levels will fall from 3500ft ahead of the front to 1000-1500ft behind the front as snow briefly lightens. The trailing upper low will bring in more light to moderate snow for the region this afternoon/evening and this will gradually end by tomorrow morning. WPC probabilities for an additional 6 inches of snow are >50% above about 2000-2500ft. ...North to Central Rockies and central High Plains... Days 1-3... The upper low will cross the Divide on Thursday and split into two pieces -- the northern portion will continue eastward along the Canadian border as a weakly closed low while the southern portion digs through the Great Basin before turning east to the central Rockies. This will spread snow over much of the region as colder winter-like air ushers in behind the cold front. With the SW flow aloft, the central ID ranges, SW MT, and WY ranges will be the focus for the heaviest snow. By Friday, height falls reach the western High Plains where a low-level upslope component to the CO Rockies and adjacent High Plains will promote additional snowfall in the wake of the cold front. All snow will end around 12Z Saturday as the trough continues steadily through the Plains to the Upper Midwest. For the Northern Rockies, the cold front will reach northwest MT Wednesday morning with a gradual progression to Wyoming through Wednesday night. The cold air behind the front is impressive (700mb temps -12 to -16C) which will plunge temperatures 25-35 degrees pre- to post-FROPA. Snow levels ahead of the cold front will be around 5000-6000ft over MT before dropping to 2000-3000ft behind the front as rates decrease. Snow levels over WY rise to 8000ft in the warm sector Wednesday before dropping to 3000ft Wednesday night behind the front. Snow levels around 9000ft in CO on Thursday drop to 4000-5000ft through the day Friday. WPC probabilities for at least 8 inches of snow are >50% above about 5000ft in northern ID/northwest MT and 6000ft in the central ID ranges. Over southwest MT (Absarokas) to the Tetons, Wind River Range, and Bighorns, WPC probabilities for at least 8 inches of snow are >50% above about 7000-9000ft from northwest to southeast. Over UT into CO, amounts will generally be lighter but at least 6 inches of snow is likely (>50% chance) above about 9000ft. Lighter amounts (1-2") are expected along/east of the Front Range into metro Denver as rain turns to snow Friday evening. As a final note, the sharp cold front should produce snow squalls or convective snow bands along/ahead of it today and Thursday. This activity could cause short-lived but impactful drops in visibility and hazardous travel. The probability of significant icing for days 1-3 across the CONUS is less than 10 percent. Fracasso $$