924 FOUS11 KWBC 160756 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 356 AM EDT Thu Apr 16 2026 Valid 12Z Thu Apr 16 2026 - 12Z Sun Apr 19 2026 ...North to Central Rockies and Central High Plains... Days 1-2... Shortwave trough moving across the interior Northwest will amplify as it traverses into the Rockies, with 500-700mb heights falling to between the 1st and 10th percentiles of the CFSR climatology. This feature will remain generally progressive despite the amplification, leading to broad but impressive ascent through height falls/PVA combined with jet-level diffluence (with some coupling noted over the Central Rockies leading to lee cyclogenesis/surface low development. Moisture will increase modestly, primarily in the 500-700mb layer as streamlines suggest Pacific flow downstream of the primary trough axis leading to elevated specific humidity in the mid-levels despite TPWs remaining near-normal. Where the broad synoptic ascent overlaps the greatest mid-level moisture, precipitation will overspread the region, generally falling as light to moderate snow above 6000 ft, at least initially. However, these snow levels will fall to as low as 2000-3000 ft behind a sharp cold front which will traverse E/SE beneath the primary trough, with upslope flow into terrain and steep lapse rates beneath this cold core leading to enhanced ascent and locally even lower snow levels at times. Since this system remains progressive, total snowfall will be somewhat modest, but locally much heavier accumulations are likely, especially in the WY/CO terrain where some easterly low-level flow around the developing surface low will enhance moisture and ascent. 2-day WPC probabilities indicate the heaviest snowfall will occur across the higher elevations from the Absarokas into the Wind Rivers, Big Horns, Laramies, Park Range of CO, and Front Range. In these areas, the probability of at least 8 inches of snow is between 50-90%, with locally more than 12 inches possible (30-50%) across the Big Horns. Lighter snows (up to 4") are likely into the High Plains of WY and CO, including along the Palmer Divide. Additionally, snow squalls continue to appear possible along the cold front, especially across parts of NV, UT, and WY today. While snow accumulations from any squalls will be minimal, briefly heavy snow rates and gusty winds could create dangerous travel. ...Northern Plains... Days 1-2... The strong cold front moving through the Central Rockies and High Plains Thursday into Friday will continue eastward, reaching the Northern Plains by Friday morning. Behind this front, the upper trough will split, with a closed northern stream impulse moving along the ND/Canada border on Friday, while secondary jet energy lifts into the Upper Mississippi Valley to help drive ascent. The overlap of the low-level baroclinic zone and this jet evolution will result in impressive mid-level fgen acting upon a modestly moistening column to produce a stripe of heavy precipitation. Forecast profiles indicate that the low-level thermal structure will be marginally favorable for snow, but the strong ascent into (or just above) the DGZ will help dynamically cool the column to result periods of heavy snowfall rates which could reach 1-2"/hr at times as reflected by the WPC prototype snowband tool. With most of this occurring before daybreak Friday, the snow could accumulate efficiently during p-type changeover, and WPC probabilities indicate a low risk (10-30% chance) of 4+ inches of snow within this band, especially in parts of ND. Farther east, some light mixed precipitation is also possible, reflected by WPC probabilities that rise to 50-70% for at least 0.01" of ice for parts of NW MN. Weiss $$