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FOUS11 KWBC 082020
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
320 PM EST Thu Jan 8 2026

Valid 00Z Fri Jan 09 2026 - 00Z Mon Jan 12 2026


...Upper Midwest & Upper Great Lakes...
Day 1...

A storm system will track from KS this afternoon on north and east
into IA by this evening, then over northern MI by Friday morning
producing a narrow, but potentially heavy stripe of snowfall just
to it's northwest. Dynamic cooling beneath a coupling jet-streaks
structure is a plausible scenario from as far south and west as
eastern NE to as far north as the MI U.P.. Given the rapid
progression of the QPF shield, accumulating snow over 1-2" will be
tough for areas south and west of northern WI. However, over
northern WI and the MI U.P., the timing of the changeover to snow
and the 700 mb low track coincides with the middle of the night,
allowing for a better chance for snowfall accumulations. Snowfall
rates of 1-2"/hr over northern WI and the MI U.P. are also becoming
more likely per the 12z HREF, which will support greater
confidence in heavy snowfall accumulations over 4". Snowfall rates
and associated reduced visibilities are the expected hazards, along
with the potential for slippery overnight travel. Marquette's area
and the Huron Mts in particular will have better chances for heavy
accumulating snow as onshore, lake- enhanced snowfall ensues. Snow
tapers off Friday morning as the storm races north into Ontario.
WPC probabilities shows moderate chances (40-80%) for snowfall
totals >6" in MI's Huron Mountains into northern WI. There is also
the potential for light ice accumulations from northern IA and
southern MN to northern WI and the western MI U.P. during the onset
of the event with WPC probabilities showing moderate chances
(30-50%) for ice accumulations over one-hundreth of an inch. Ice
accumulation could occur near the evening rush hour in southern MN
and central WI.

...Central/Southern Rockies & Adjacent High Plains...
Day 1...

Following an initial shortwave ejecting into the Plains this
afternoon, a second and more vigorous upper level shortwave over
the Great Basin heads east for the Four Corners region tonight.
This system will bring with it not only additional Pacific moisture
but height falls, better PVA, and jet streak dynamics aloft.

As enhanced Q-vector convergence heads for the Front Range of the
Rockies and the High Plains this evening, a closed 700mb low will
develop over northern NM that gives rise to a surface low forming
in lee of the Sangre De Cristo mountains. Snow levels will quickly
fall below 5000ft by Friday morning. Meanwhile, low-level easterly
winds over the central High Plains fosters upslope flow into
southern CO and northern NM peaking Friday morning as the 700mb low
tracks just south of Raton Pass. There remains some latitudinal
disagreement on the placement of the best 700mb FGEN as the 700mb
low emerges into northeast NM and tracks towards the OK/TX
Panhandles. Where the best FGEN forcing sets up and the strength of
the 700mb low will be vital in where the heaviest snowfall occurs
and how far east away from the Raton Mesa and Front Range the band
of heavy snow can advance. Beneath the 700mb FGEN, >1"/hr snowfall
rates are expected. The 12z HREF and WPC Snowband Probability
Tracker depicts this well with 1"/hr snowfall rates possible
anywhere between southwest KS to the northern TX Panhandle. As the
700mb low moves northeast Friday afternoon, it will weaken and open
up into a progressive 500mb shortwave, resulting in frontolysis
over the High Plains that reduces precipitation rates and weakens
dynamic cooling aloft.

At this time, WPC probabilities are highlighting the usual
suspects (Palmer Divide, Front Range, Raton Mesa) as having
moderate-to- high chances (>70%) for snowfall totals >4". I-25 at
Raton Pass sports moderate-to-high chances (50-70%) for snowfall
totals >6". Localized snowfall totals >8" along the peaks of the
Sangre De Cristo and Raton Mesa are possible. Farther east, WPC
probabilities show high chances (60-90%) for snowfall totals >4" in
southeast CO, northeast NM, the far western OK Panhandle, and the
northwest tip of the TX Panhandle. The WSSI shows widespread Minor
Impacts (winter driving conditions; use caution when driving) for
much of the central High Plains with localized Moderate Impacts
possible over northeast NM.


...Great Lakes into the Northeast...
Days 2-3...

By Saturday night, the shortwave trough responsible for the heavy
snow in the the southern and central Rockies/High Plains tracks
eastward into the MS Valley. As this occurs, a deep, closed, 500mb
low in southern Canada plunges into the Upper Midwest and Great
Lakes. The latest guidance continues its recent trends of keeping
the much stronger northern stream disturbance separated just enough
to shear apart the southern shortwave instead of phasing together
with it. Given the overall system becoming more progressive due to
reduced phasing and less interaction between the better northern
stream dynamics and enhanced southern stream moisture, snow amounts
across eastern WI and northern MI have come down quite a bit with
this package. The latest WPC probabilities still show moderate to
high chances (50-75%) for snowfall amounts >4" across portions of
northern Michigan, but odds for >6" are now only 30-50%. The one
exception to that is across a small portion of the U.P. of Michigan
where some additional lake enhancement will give higher odds
(50-70%) of >6".

The same storm responsible for the snow over the northern Great
Lakes Saturday night into Sunday will also produce a hazardous
wintry mix across the northern Appalachians into northern New
England. The Northeast will lay ahead of a strong >750kg/m/s IVT
that will direct copious amounts of moisture northward Saturday
into Saturday night. At the same time, a cold front will provide
just enough cold/dry air at the surface with Canadian high pressure
to the north creating a weak CAD signature over the Northeast.
This healthy 850-700mb WAA will support a classic overrunning setup
of >0C air aloft causing a mixture of sleet/freezing rain to
unfold beginning Saturday afternoon and continuing into Saturday
night/early Sunday morning. Precipitation is looking more likely to
start out as snow farther north in northern New England Saturday
night, with the potential to stay all snow for a longer period of
time. This is due to secondary coastal development just south of
Long Island and Cape Cod, which may help to keep sub-freezing
surface temperatures entrenched. How long this colder air stays
locked in will go a long way in determining snow amounts there, and
if snow will eventually change to a wintry mix. Still, the greater
concern for frozen precipitation, whether it be freezing rain or
snow, is for many of the interior mountain ranges such as the
Catskills, Berkshires, Greens, Adirondacks, and Whites where
surface temperatures have better odds of staying sub-freezing
Saturday night and into Sunday morning. Once the secondary surface
low pressure takes over Sunday afternoon, most places across the
Northeast will end as snow as a strong cold frontal passage ushers
in a much colder air mass in its wake. Some of this snow will have
the potential to be moderate to heavy across parts of Maine,
pending additional coastal development.

The latest WPC probabilities indicate moderate chances (40-70%)
for minor ice accumulations over one-hundreth of an inch across the
Berkshires, Greens, Adirondacks, and Whites, with low chances
(10-30%) for ice greater than a tenth of an inch. In terms of snow,
WPC probabilities for >4" are moderate (40-70%) from the northern
Adirondacks, Greens, and Whites into northern Maine, with low
chances (10-30%) for 6 inches or more through Sunday evening.


Snell/Miller/Mullinax


$$

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