923
FOUS11 KWBC 052005
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
305 PM EST Fri Dec 5 2025

Valid 00Z Sat Dec 06 2025 - 00Z Tue Dec 09 2025


...Pacific Northwest, Northern & Central Rockies...
Days 1-3...

A highly active storm track with several significant atmospheric
rivers into the Northwest will usher in copious amounts of Pacific
moisture from the Pacific Northwest on east into the Northern and
Central Rockies the next few days. A steady barrage of >90th
climatological percentile PWATs will stream across the Pacific
Northwest into the Great Basin and Rockies through Saturday, with
another round of >90th percentile PWATs arriving in the Pacific
Northwest Sunday into Monday. Synoptic-scale forcing for ascent
will be aided by a persistent NW-SE oriented 250mb jet streak with
its diffluent left exit region overhead. Snow levels over the
Pacific Northwest will dip as low as 3,000ft while the Northern
Rockies generally hover around 4,000ft. As height falls occur over
the Northwest through Saturday, snow levels will drop to as low as
2,000ft. That being said, the heaviest snowfall will be confined to
elevations above 5,000ft in the Bitterroots, Lewis Range, and
Sawtooth, above 6,000ft in the Tetons, Absaroka, Big Horns, Bear
River, and Wasatch Ranges, and above 7,000ft in the central WY/CO
Rockies. Snow looks to taper off across the Central Rockies by
Saturday evening, but the next atmospheric river will deliver
another plume of Pacific moisture and another round of heavy
mountain snowfall across the Pacific Northwest and northern Rockies
Sunday into Monday.

WPC probabilities continue to be impressive on Day 1 across the
higher terrain from Glacier NP through Yellowstone NP including
portions of the Sawtooth/Salmon River ranges, Absarokas, terrain of
NW WY, northern Utah, and into the Park Range of CO. Here, WPC
probabilities reach above 70% for 8+ inches, with locally higher
amounts of 1-2 feet generally above 6000 ft. Over the next few
days, WPC probabilities paint a wintry picture across many of the
Northern and Central Rockies, as well as the higher elevations of
the Cascades (above 5,000ft) with high chances (>70%) for
additional snowfall totals >18" in all of these listed ranges and
elevations through Sunday. In fact, the higher elevations of the
Lewis Range, Bitterroots, and Tetons have moderate-to-high chances
(50-80%) for snowfall totals >24". Moderate to heavy snow continues
later into Days 2 and 3 over the WA Cascades and northern Rockies,
though probabilities suggest less snowfall compared to the more
snowy stretches tonight into Saturday. The WSSI shows many areas of
Minor and Moderate Impacts across the Northern and Central
Rockies, including some locally Major Impacts. The Major Impact
potential areas (considerable disruptions; dangerous travel and
widespread closures) include areas along the Wasatch east of Salt
Lake City and the more remote areas of these Intermountain West
ranges. Residents in these mountain ranges should prepare for a
multi-day stretch of winter weather that results in difficult and
treacherous travel conditions.

...Northern Plains & Midwest...
Days 1-2...

A fast-moving clipper system, aided by a slug of Pacific moisture
combined with strengthening low-level frontogenesis and warm
advection, will support a swath of moderate to heavy snow from the
northern Plains into the Midwest the next couple of days. The band
of snow first starts to develop across the Dakotas late tonight
into Saturday morning, then heads for southern MN and
northern/central IA as it intensifies late Saturday afternoon and
evening. The band then begins to weaken by early Sunday morning as
the snow reaches the Lower Great Lakes and OH Valley.

The latest WPC probabilities have increased with this forecast,
now supporting probabilities of 50-90% for snowfall totals >4" for
locations that banding (mentioned above) is most likely across the
Midwest. However, given the favorable synoptic and mesoscale
processes at play, a swath of heavier and more impactful snow still
remains on the table, as evident in the low-to-moderate chances
(30-50%) for snowfall totals >6" over northern/central IA. By
Sunday, low probabilities (10-40%) of >4" of snow extend into
southern Wisconsin and northern Illinois as the quick-moving wave
weakens on its track into the Lower Great Lakes and OH Valley.
Those in the Midwest should continue to monitor the forecast
closely as additional changes in the placement and totals of the
heaviest snowfall could still change over the next 24 hours.

...Great Lakes & Northeast...
Days 1-3...

Periodic mid/upper level impulses rotating within a broad cyclonic
flow pattern will continue to support rounds of light-to-moderate
lake effect snowfall across the upper Great Lakes through Monday. A
cold frontal passage Saturday into early Sunday morning
revitalizes LES bands over the Michigan U.P. and downwind of Lake
Ontario over the Tug Hill. Then, the fast-moving clipper from the
Midwest races across the Great Lakes and Northeast later Sunday
into Monday, bringing more lake effect snow and likely a period of
steadier synoptic snow to interior portions of the Northeast and
northern New England. The latest 12Z guidance continues to suggest
a fairly flat mid/upper level shortwave as it passes over the
region, which would limit snowfall potential. That said, it would
not be surprising to see models trend a bit more amplified and more
snowy in future model cycles, so continue to monitor the forecast
in the coming days.

WPC probabilities show overall low chances (10-40%) of >4" of snow
across portions of northern Michigan downwind of Lake Superior and
Lake Michigan Saturday into Sunday. Low chances (10-30%) of >4" of
snow then extend downwind of Lake Erie and Lake Ontario and across
parts of northern New England Sunday into Monday.


Miller/Mullinax







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