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FOUS11 KWBC 120808
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
308 AM EST Mon Jan 12 2026

Valid 12Z Mon Jan 12 2026 - 12Z Thu Jan 15 2026


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

Ongoing westerly flow over Lake Ontario will keep additional heavy
snowfall of 6-12" in the forecast today over the Tug Hill Plateau,
while minor amounts generally between 1-4" occurs around the
Buffalo area and the Adirondacks. By tonight, a Canadian clipper
system will race east over southern Ontario with just enough low-
level WAA and a plume of 700-300mb moisture aloft to support a
brief overrunning setup over the MN Arrowhead, northern WI, and the
western MI U.P.. Ice accumulations are likely to be less than a
tenth of an inch, but WPC probabilities show moderate chances
(>50%) for ice accumulations over on-ehundreth of an inch. Slick
spots on untreated surfaces are possible Monday night and into
Tuesday morning in affected areas.

As the clipper continues to advance east into southeast Canada, a
robust 500mb vorticity max diving south will accompany a strong
cold front that induces strong CAA over Lake Superior Tuesday
night. Snow will increase in intensity over the Michigan U.P. as
surface-850mb delta Ts dramatically increase and low-level lapse
rates sharpen. The upper-level trough continues to dive south
through the Great Lakes on Wednesday and the same CAA regime will
race south over Lake Michigan. Guidance is coming into better
agreement on the formation of a potent single-band LES setup
producing a swath of heavy snow over northwest IN that could
oscillate at times to as far west as the WI/IL lake shores and as
far east as southwest MI. Meanwhile, much of Michigan's Mitten will
contend with multi-band lake effect streamers as a surface trough
pivots over the Great Lakes Wednesday and into Wednesday night.
This same trough axis, along with the CAA over the Great Lakes,
will trigger lake-enhanced snowfall over northern OH, northwest PA,
and western NY by early Thursday morning. Snowfall will become
more synoptically-enhanced by early Thursday morning as a 700mb low
tracks over Lake Erie and would support heavy snowfall into the
day on Thursday as well.

24-hour WPC probabilities through 12Z Wednesday show
moderate chances (40-60%) for snowfall totals >6" along the
Keweenaw Peninsula and both the Huron and Porcupine Mountains of
the MI U.P.. 24-hour probabilities through 12Z Thursday depict
northwest IN as having moderate chances (40-60%) for snowfall
totals >6". Note that should 1-2"/hr rates materialize, localized
amounts approaching a foot of snow are possible. Lastly, through
12z Thursday, the first 6-12 hours of the impending winter storm
show low chances (10-30%) for snowfall totals >4", but with the
storm likely to produce additional heavy snow along the Chautauqua
Ridge and into western NY, expect heavier snowfall totals to
envelop these areas through Thursday. The WSSI-P currently shows
moderate-to-high chances (50-70%) for at least Minor Impacts over
northwest IN, northeast OH, and western NY through Thursday
morning.

...Upper Ohio Valley, Central Appalachians, & Northeast...
Days 3-3.5...

A robust 500mb shortwave trough over the Upper Midwest will race
southeast toward the Ohio Valley Wednesday night. There remains a
fair amount of uncertainty and model spread that is making this
forecast tough in the Ohio Valley and as far east as the I-95
corridor, but the higher confidence areas are the spine of the
Appalachians. As the 500mb shortwave deepens into a closed upper
low Wednesday night, an accompanying strong cold front will
collide with the central Appalachians with strong 925-700mb layer
CAA. The combination of brisk NWrly flow and excellent PVA aloft
ahead of the upper low will produce heavy snowfall rates from the
Laurel Highlands of southern PA on south to the Blue Ridge and
Smokey Mountains. Snow is likely to continue beyond the scope of
this short-term discussion as cyclonic flow around the western
flank of the storm system sustains favorable upslope flow into the
central Appalachians. The WSSI-P is showing >50% chances for a
at least Minor Impacts over the Smokeys of TN/NC, and both the
windward slopes and peaks of the central Appalachians. Residents
and travelers should plan for a disruptive snow event in central
Appalachians Wednesday evening and into Thursday.

From the Ohio Valley on north through western PA and into the
Northeast the forecast is more murky. Guidance across the board
shows different evolutions and tracks of the aforementioned 500mb
low. The CMC shows a lack of deepening/phasing of 500mb vort
maxima that keeps the synoptic-scale forcing limited. The ECMWF/EC-
AIFS/UKMET camps show a closed low by tracking across the lower
Great Lakes and into the Northeast. To illustrate the ongoing
changes, the 00Z ECMWF from 24 hours ago had a closed low south of
Louisville, KY by 12Z Thursday, while the latest 00Z ECMWF has the
closed low near Cleveland, OH at the same time Thursday. Lastly,
the GFS/GEFS is farther south over the OH Valley that then heads
for the Mid-Atlantic coast as a weakening closed low. All these
evolutions lead to different snowfall footprints, particularly
along the I-95 corridor and northern Mid-Atlantic. No matter the
track of the upper-low, the meteorology involved supports periods
of snow north of the emerging 700mb low. The EPS/GEFS both show the
left-exit region of a strengthening jet streak off the southeast
coast being placed over the Northeast, which also pairs favorably
with 700mb Q-vector convergence on both GFS and ECMWF solutions
over the eastern Great Lakes and interior Northeast. Through 12Z
Thursday, WPC probabilities show northern OH (including the
Cleveland metro) on north and east along the Chautauqua Ridge and
the Adirondacks showing low-to-moderate chances (30-50%) for >4" of
snowfall.

Residents and travelers across the Northeast will want to monitor
the forecast closely in the coming days as this complex forecast is
likely to change in the coming days. The lowest confidence in terms
of snowfall amounts and impacts are along the I-95 corridor as
potential scenarios range from a significant winter storm for areas
along I-95 in southern New England to minor snow accumulations at
most depending upon the strength and track of the approaching
upper-low. Not only are amounts unclear, but boundary layer
temperatures at the onset Wednesday night and early Thursday
morning would support rain as the initial precipitation type before
changing over to snow. For now, the spine of the Appalachians are
favored to see accumulating snowfall late Wednesday into Thursday.


Mullinax





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