FOUS11 KWBC 110625
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
125 AM EST Wed Feb 11 2026

Valid 12Z Wed Feb 11 2026 - 12Z Sat Feb 14 2026

...Eastern Great Lakes and Northeast...
Day 1...

The strong clipper-type low will continue to push east off the New
England coast as the driving shortwave aloft races to the
southeast. The vorticity accompanying this shortwave will help
develop secondary low pressure along a triple point well offshore
(near Nova Scotia), with this secondary low deepening as it pulls
away. Although this low should be well too far east to bring any
direct impacts to the Northeast, the guidance continues to indicate
an inverted trough will pivot cyclonically around the low, bringing
enhanced ascent to the coast of Maine, resulting in bands of heavy
snow. Some uncertainty continues with the exact placement of these
bands, but the high-res is quite agreeable in their occurrence.
This suggests that while WPC probabilities for 4+ inches are just
30-50% across primarily the Downeast coast of Maine, some locally
higher totals are probable as reflected by pronounced spread in the
WSE plumes.

Additionally, in the wake of this clipper, increasing CAA
atop the Great Lakes, despite significant ice cover, will result in
periods of lake effect snow, primarily E/SE of Lake Ontario with
some lighter snowfall east of Lake Erie which is mostly ice
covered. WPC probabilities for this LES are high (>70%) for 4+
inches for the western Adirondacks, Tug Hill Plateau, Finger Lakes
region, and northern Chautauqua Ridge. The greatest accumulations,
which may exceed 8 inches (30% chance) are across the Tug Hill.


...Sierra Nevada to the Central/Southern Rockies...
Days 1-2...

A closed mid-level low positioned along the coast of northern CA
will generally fill in place as the accompanying longwave trough
elongates back to the southwest as secondary vorticity energy
rotates through the base ot approach southern CA and Baja by Friday
morning. This stalled evolution will result in a resurgence of an
upper level jet streak to sharpen downstream of this trough axis,
and while the secondary jet streak tonight into Thursday won't be
as powerful as the lead jet, it will maintain moisture advection
and broad LFQ diffluent ascent from CA into the Central Rockies.
The overlap of this jet streak with broad but persistent SW mid-
level flow also downstream of the primary trough axis will surge
moisture eastward as far as CO as reflected by NAEFS IVT
percentiles surging to above the 99th percentile in CO, with
prolonged anomalies above the 90th percentile back into the Great
Basin.

This plume of moisture will be primarily shed eastward within a WAA
plume, so snow levels will be generally 6000-7000 ft, lowering
slowly as the trough axis pivots eastward, but this will likely be
accompanied by rapid drying and a resulting cutoff of
precipitation. For this reason, the heaviest snowfall accumulations
are likely to be above 7000 ft (as high as 8000 ft in CO), with a
wane in precipitation expected as snow levels fall. WPC
probabilities D1 are high for at least 6 inches of snow in the high
Sierra, the Uintas/Wasatch, the Tetons/Wind Rivers, and parts of
the CO Rockies including the Park Range. D2 probabilities compress
and fall rapidly, leading to just residual elevated probabilities
above 30% for 4+ inches in the CO Rockies.


...Southern Rockies...
Day 3...

The same secondary shortwave responsible for elongating the trough
over CA/Great Basin D2 will shed eastward Friday morning, moving
across southern CA/Baja Norte before closing off once again near
the Four Corners Friday evening. This evolution will promote
downstream ascent through impressive height falls paired with
modest jet streak amplification, leading to widespread deep layer
lift spreading into the Four Corners and southern Rockies Friday
into Saturday. The antecedent thermal structure will be modest for
snowfall (snow levels 8000-9000 ft), but increasing ascent within
a moistening column will expand precipitation and allow for snow,
which could be heavy, especially in the higher terrain of the
Sangre de Cristos, White Mountains, and San Juans, with some
dynamic cooling of the column possible later D3 as some deformation
develops across northern NM. Still a lot of uncertainty in the
exact evolution, but at this time WPC probabilities indicate a
moderate to high risk (50-90% chance) for at least 4 inches in the
higher terrain.


The probability of significant icing across the CONUS is less than
10 percent.


Weiss


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