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FOUS11 KWBC 271931
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
231 PM EST Tue Jan 27 2026

Valid 00Z Wed Jan 28 2026 - 00Z Sat Jan 31 2026


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

The seemingly endless cyclonic flow that has kept the LES machine=20
cranking over snow belts of the Great Lakes looks to continue
through the remainder of the work-week. Frigid 850mb temperatures=20
will persist with temperatures around -18 to -24C, which are below
the 10th climatological percentile. According to GLERL, Lake Erie=20
is essentially ice covered, so available moisture will be limited=20
there while Lakes Superior and Ontario remain largely open. W-NWrly
low-level winds will continue through Wednesday before the approach
of a sharp 500mb shortwave pivots through and shifts winds more out
of the N-NNW by Thursday. Northerly flow continues Friday as high
pressure builds in over the Northern Plains. 72-hour WPC
probabilities depict high chances (>70%) for snowfall totals >4"
over the northern tier of the Michigan U.P. and down wind of Lake=20
Ontario to the south of an over the Tug Hill. The area with the=20
best odds of seeing over a foot of snow over the next few days are=20
near the Oswego, NY area where WPC probabilities for over a foot of
snow are in the moderate range of probabilities (40-60%).=20


...Cascades & Olympics...
Days 1-3...

A series of storm systems tracking into the Gulf of Alaska will
direct rounds of moisture and WAA at western WA through the
remainder of the week. Strong upslope flow should support locally
heavy snowfall totals as low as 4,000ft, but most heavy snow will=20
reside in the more remote areas above 5,000ft. Snow levels rise=20
from 4000 to 5000ft over the WA Cascades Wednesday through=20
Thursday. By Friday, snow levels approach 6,000ft by Friday in
western WA. WPC probabilities for >4" is high (>70%) around Stevens
Pass, but lighter accumulations around Snoqualmie are anticipated
at this moment given the higher snow levels.

...Northern & Central Plains...
Days 2-3...

A weak Pacific shortwave trough tracking NW-SE will ride along a
nearby 850mb front to support periods of snow from the northern
High Plains on south in the the central High Plains. Snow is not
expected to be overly heavy, although the Black Hills through
orographic lifting may be able to see snowfall amounts surpass 6".
This is supported in WPC probabilities which show moderate-to-high
chances (50-70%) for >4" of snow in the Black Hills, and low
chances (10-30%) in their peaks for >8". Elsewhere, from eastern MT
on south and east through the Missouri River Valley, most snowfall
accumulations are likely to range between 1-3". Some hazardous
travel is possible, especially where roads temperatures are at or
below freezing in wake of the recent extreme cold.


...Southern Appalachians & Mid-Atlantic...
Days 3-3.5...

...Confidence In Impactful Snowfall Increasing For the Southern=20
Appalachians and Southern Mid-Atlantic...

To say there remains a large amount of model spread in the
potential winter storm beyond Day 3 would be an understatement. In
the past 24 hours, ensemble guidance have flipped camps to where
the GEFS are the snowier members, CMCE are more in the middle, and
the EC-EPS are trending less snowy. It is worth noting that AI=20
ensemble membership are not as snowy as the GEFS, but show a little
more snow than the EC-EPS, making this an interesting test in how=20
the AI ensemble membership performs.=20

Regarding the setup-- WPC Cluster Analysis shows this potential=20
winter storm comes down to several factors: 1) strength of the=20
emerging Great Lakes shortwave trough. 2) speed of the shortwave=20
trough. 3) tilt/amplitude of the shortwave trough as it tracks=20
east. 4) Confluence strength near Nova Scotia. They all work=20
together in an intricate dance that makes for difficulties in=20
modeling. A stronger/slower shortwave can buy time for confluence=20
over New England and Nova Scotia to weaken, giving the shortwave=20
more time to amplify, and allow for closer storm tracks to the=20
coast that bring heavy snow as far west as the I-95 corridor (some=20
GEFS members and some CMCE members). Where the shortwave is=20
stronger but progressive, heavier snowfall occurs but largely=20
closer to the coast and as far west as the NC Piedmont (CMCE=20
members, UK ensembles, split EC/GEFS members). If the shortwave=20
trough is more progressive and cannot separate itself from the=20
larger TPV to the east there is less amplification, it results in=20
a flatter and more positively/tilted shortwave trough, and thus the=20
storm remains largely out at sea (EPS, EC-AIFS ensembles, some=20
GEFS/CMCE members). It is worth noting that, while the EC-AIFS has=20
largely performed well inside of 5 days much of the winter season,=20
the EC-AIFS and ECMWF did suppress the track of the most recent=20
winter storm too much ~4-5 days out before correcting northward=20
inside of 72 hours out.

This setup is highly timing dependent; from the primary shortwave
trough currently east of Hudson Bay, to the interaction/spacing of
the 500mb cyclonic gyres in southeast Canada and south of Iceland
that promote the confluence ahead of the potential storm, to the=20
incoming Pacific shortwaves that track into western Canada and
adjust the strength/position of the western North America ridge.=20
There remain a host of embedded shortwaves that will work together=20
to create a complex storm evolution off the East Coast. Whatever=20
the current model solutions show beyond 72 hours out is unlikely to
be the final product. Expect additional model changes in the=20
coming days. If there is one thing that has increased in confidence
in the past 24 hours, it is the opportunity for coastal flooding=20
and beach erosion along the Mid-Atlantic coast. Please refer to our
"What We know, What We Don't Know" social media post for=20
additional information.

The one thing they do agree on is this upper trough tracks through
the OH Valley Friday afternoon with sufficient PVA and 850-500mb=20
mean layer moisture to support snow from central KY to the southern
Appalachians through Friday evening. WPC probabilities do
show increasing chances for at least minor accumulations >2" over
KY and northeast TN, while there are low-chances (10-30%) for
snowfall totals >4" through early Saturday morning in the TN/NC Smokeys
and Blue Ridge of NC. Residents and those traveling to the=20
Carolinas on north up the East Coast will want to continue=20
following the forecasts from WPC and your local NWS WFO for the=20
latest regarding this potential winter storm.=20


The probability for significant icing is less than 10 percent.


Mullinax




...Extreme Cold Key Messages are in effect. Please see current Key
Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=
stKeyMessage_1.png__;!!DZ3fjg!6VI14otitwAAstNrC60qAGwJSrOE6Zf0oLu0MtZRucHys=
6sfDSsnz6A0nRg5hdjsoJ-6sT4HYazaHiiRfGLVWtSFuMg$=20



$$

=3D =3D =3D
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