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FOUS11 KWBC 012025
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
325 PM EST Thu Jan 1 2026

Valid 00Z Fri Jan 02 2026 - 00Z Mon Jan 05 2026

...Great Lakes...
Days 1-3...

Persistent west-northwesterly flow continues across the Great
Lakes over the next few days. This is following in the wake of a
strong arctic front that exited the East Coast to kick off the new
year. This cyclonic flow pattern will be enhanced late tonight
into Friday as another shortwave passes through the flow, leading
to renewed CAA before another weak shortwave swings through on
Saturday and ridging finally develops by the end of the forecast
period.

The primary snowfall hazard will be associated with widespread
heavy lake effect snow (LES) in the favored W/NW snow belts. The
most intense LES will likely begin late tonight through Friday
night as 850mb temperatures plummet to as low as -15C to -20C,
across lakes that, while they have cooled, are mostly ice- free.
This will lead to impressive SBCAPE as high 5000-1000 J/kg to
support a long duration 1-2+"/hr LES event, especially downwind of
Lakes Erie and Ontario due to upstream connections. The heaviest
accumulations D1 and D2 are expected across the Chautauqua Ridge
and along/just barely south of the Tug Hill plateau before
shifting a little south into D1.5-D2. WPC probabilities are high
(>80%) for 6+ inches in these areas D1, continuing east of Lake
Ontario D2. Locally 2-4 feet of additional snow is possible east
of Lake Ontario before heavy LES wanes during late-D2 into D3.
Downwind of the other Great Lakes, WPC probabilities D1 feature a
low risk (20-40%) for 6+ inches in the eastern U.P., but this
wanes quickly during D2.


...Western U.S. Mountain Ranges...
Days 1-3...

Shortwave with subtropical origins will cross over the central
Great Basin tonight and Central Rockies early Friday over an
expanding Rockies upper-level ridge that will help amplify an
eastern Pacific trough over the next few days. Downstream of this
initial shortwave/impulse, snow levels will remain elevated at
7000-9000 ft throughout much of the Great Basin, Four Corners and
central/northern Rockies before settling around 70000ft by the end
of D1. WPC probabilities D1 for 6+ inches of snow reach above 70%
in parts of the Wasatch, Central Rockies, and Tetons/Wyoming Range
of the Northern Rockies.

Then on D2-D3 a more pronounced surge of precipitation spreads
onshore CA once again as a deep trough amplifies offshore,
resulting in impressively amplified southerly flow. This will push
moisture onshore as IVT exceeds 500 kg/m/s (>80% chance). Once
again snow levels will be elevated within the accompanying WAA,
reaching as high as 8000 ft into the Sierra (although much lower
around 6000 ft across the Shasta/Trinity region). The pronounced
moisture will result in heavy snow again above these levels, and
with SLR expected to be low, it will be an impactful snowfall due
to snow load. Precipitation will also reach northward along the
West Coast mountains to the Cascades and inland across the Great
Basin towards the favorable upslope southwest facing terrain. Snow
levels will remain around 6000ft across these regions, with lower
levels (around 4000-5000ft) in the Cascades. WPC probabilities
D2-D3 are high (>70%) for more than 6 inches across the Sierra and
northern CA ranges, as well as the WA Cascades, Sawtooths of ID,
and Tetons of WY. More than two feet of snow is likely (70-90%)
over the next three days in the Sierra.


...Columbia Basin and Gorge...
Day 1...

Increasing southerly mid-level flow over the Pacific Coast will
continue to spread moisture northward tonight, aided by a
weakening shortwave lifting from CA into the northern Great Basin.
As this moisture spreads into the Pacific Northwest, it will
overrun a slowly retreating ridge of high pressure, manifesting
with easterly winds draining into the Columbia Basin/Gorge to
maintain cold surface air. This setup is favorable for light
freezing rain with modest accretions as reflected by WPC
probabilities that reach 20-40% for 0.1 inches of ice after 00Z
this evening. Although amounts are generally light, impacted
travel is likely tonight into Friday morning due to slippery
roadways.


Weiss/Snell



$$

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