FOUS11 KWBC 310712
QPFHSD
Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
212 AM EST Wed Dec 31 2025
Valid 12Z Wed Dec 31 2025 - 12Z Sat Jan 03 2026
*** New Year's Eve Snow Squall Threat From Michigan through
Interior Northeast ***
...Great Lakes, Central Appalachians, Interior Northeast...
Days 1-3... Maximum impact level from WSSI: Major
A deep cold core low will meander near Hudson Bay through the rest
of the week as a series of reinforcing troughs and impulses track
on its southwest/southerly periphery over the Great Lakes and into
the Northeast. This will maintains bouts of lake-effect snow off
all the Great Lakes, but especially east of Lakes Erie and Ontario.
A rather robust upper through will move out of the Upper Great
Lakes this morning and across NY/PA tonight. CAMs show this arctic
front bringing a notable snow squall threat across eastern Michigan
this afternoon and the eastern Great Lakes/PA/NY tonight. Though
the most impactful snow squalls can be when unfrozen roads get
quickly covered with snow and temperatures plunge below freezing
(flash freeze behind the cold front), the region is currently cold
(10s/20s). Given it is New Year's Eve and the HREF shows the
highest probability of >1"/hr rates late this afternoon and
evening, the threat to drivers is more acute. Please take caution
tonight in the Interior Northeast/Mid-Atlantic. Key Messages are
highlighting this NYE snow squall threat (see link at bottom).
In addition to the lake effect snows and the snow squalls, strong
upslope flow behind the arctic cold front and ahead of the
reinforcing trough axis over the central Appalachians will favor a
few hours of heavy snow tonight over central WV northward through
western MD and into the Laurel Highlands in PA. WPC probabilities
for at least 6 inches of snow days 1-1.5 are 40-80% over this terrain.
WPC's 72-hour snowfall probabilities remain high (>70%) for
additional snow >18" in NW PA through the Chautauqua Ridge in
southwestern NY into the Buffalo Southtowns. Localized amounts
could exceed 2ft. Just southeast of Lake Ontario, WPC probabilities
are high chances (>70%) for an additional 18" or more in the
region between Syracuse, Watertown, and east of Rochester (centered
around Oswego). Over Michigan, snowfall will trend farther north
each day, but totals will still be appreciable in the eastern U.P.
where WPC 72hr probabilities for >8" are 40-90% in the eastern U.P.
and around 30-60% in northwestern Lower Michigan.
...Down East Maine... Day 1-2...
Maximum impact level from WSSI: Minor to Moderate
The vigorous mid-level trough moving through the Great Lakes today
will reach New England just after midnight with a surface low over
northern NY into VT. By tomorrow morning, the system will continue
to deepen into the Gulf of Maine, spurring a sub-1000mb low that
could quickly deepen to below 990mb as it nears the Bay of Fundy
later in the afternoon. This could focus heavier bands of snow
right along the coast with >1"/hr rates (~50% probability per the
00Z HREF). The system will be quick-moving but could still yield
several inches of snow within a 12-hr window. WPC probabilities for
at least 6 inches of snow are >50% near and east of I-95 from the
Midcoast northeastward.
...High Sierra Nevada to the Central Rockies... Days 2-3...
Maximum impact level from WSSI: Minor
A deep trough in the subtropical Eastern Pacific will lift
northward then northeastward into NorCal tomorrow, bringing an
expanse of light to moderate precipitation to the Southwest to the
Interior West. High snow levels 9000-10,000ft will limit impacts
today. For tomorrow, as the trough moves inland, snow levels of
will fall to around 8500ft as precipitation gradually ends by late
Thursday into early Friday. Moisture will stream ENE across the
Great Basin to the CO Rockies where WPC probabilities of at least 8
inches of snow are >50% above 9000ft or so in the Park Range and
also into the Tetons in WY.
After a short break, another wave of precipitation will enter the
NorCal ranges and northern Sierra with lower snow levels region-
wide -- generally around 6500ft to the north and around 7000ft in
the northern Sierra. WPC probabilities for at least 8 inches of
snow through the period are >50% above about 9000ft.
...Columbia Basin and Gorge...
Days 2-3... Maximum impact level from WSSI: Minor
Light precip spreads over the Northwest Thursday and continues
into the weekend. Sufficient cold air in place could make for some
localize light icing. WPC probabilities for >0.10" ice are low
(<20%) in the western Columbia Basin into the Columbia Gorge.
Fracasso
...Winter Storm Key Messages are in effect. Please see current
Key Messages below...
https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png
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* Origin: Capitol City Online (21:1/175)
