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

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