TZUTC: 0000
MSGID: 168200.weather@1:2320/105 2dbfe4eb
PID: Synchronet 3.21a-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0
TID: SBBSecho 3.28-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0
BBSID: CAPCITY2
CHRS: ASCII 1
FORMAT: flowed
FOUS11 KWBC 021934
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
234 PM EST Fri Jan 2 2026

Valid 00Z Sat Jan 03 2026 - 00Z Tue Jan 06 2026

...Central Plains...
Day 1...

A fast moving clipper rounding the western ridge and dropping
southeast over the Central Plains today will have sufficient 290K
isentropic ascent and 850mb WAA to foster precipitation over
eastern NE and as far east the lower MO River Valley. Soundings
show a pronounced warm nose between 850-750mb to cause a wintry mix
with surface-850mb temps sub-freezing. WPC probabilities indicate
a 70-90% chance of at least 0.01" of freezing rain, with locally up
to 0.1" of ice possible leading to hazardous travel. The WSSI does
depict Minor Impacts from Ainsworth on south and east to US routes
30 and 81 near Columbus, suggesting hazardous travel is a concern
in these areas through this evening. There is the potential for
some travel impacts all the way to the MO River, including the
Omaha metro area this evening.


...Lake Effect Snow...
Days 1-2...

Ongoing lake effect snow (LES) will continue this afternoon,
especially across the eastern U.P., and downwind of Lakes Erie and
Ontario. This LES will be driven by persistent CAA across the
lakes, leading to steep lapse rates and inversion depths that climb
towards 800mb, leading to 500-750 J/kg of lake-induced
instability. While the mean low-level flow will be a bit more W
than NW, this will help tap an upstream connection from Superior,
across Huron, and towards Lake Ontario, indicating the heaviest
snowfall will likely be along and south of the Tug Hill Plateau
through D1 and into D2 before winding down in response to brief
shortwave ridging. While periods of heavy snow are also likely in
portions of the northern L.P. and along the Chautauqua ridge, the
persistence and intensity of this snowfall should be less. This is
reflected by WPC probabilities showing moderate-to-high chances
(50-70%) for 4+ inches through Saturday over the eastern U.P. and
along the Chautauqua Ridge. The heaviest snowfall will be downwind
of Lake Ontario through Saturday with additional snowfall totals of
12-20" around Oswego, NY.

After a brief respite in response to the aforementioned shortwave
ridging, two separate, but fast moving, shortwaves will crest the
ridge to the west and dive rapidly from Saskatchewan/Alberta across
the Great Lakes. The first of these will race southeast Saturday
aftn/night, and while some enhanced ascent and subtly increased
moisture will result in light synoptic snowfall, additional
accumulations from eastern MN through western NY should be minimal.


...Upper Midwest...
Days 2-3...

One of the 500mb disturbances responsible for heavy mountain snow
in the West will round the ridge axis over the southern Plains and
head for the Upper Midwest on Sunday. The Upper Midwest lies
beneath a coupling 250mb jet streak structure that coincides with
500mb PVA and 700mb Q-vector convergence Sunday afternoon that then
moves over the Great Lakes Sunday night. In addition to the synoptic-
scale ascent aloft, strengthening 850-700mb WAA and FGEN will give
rise to a band of heavy snow from northern MN and northern WI
Sunday afternoon to the Upper Great Lakes Sunday night. There is
likely to be a >0C warm nose in southern ND, central MN, and
southern WI that leads to an icy wintry mix. As the 500mb vort max
moves east Sunday night, it will run into a stronger confluent zone
over Ontario that shears out the disturbance and leads to
lessening snowfall rates. By Monday morning, periods of snow will
envelope Upstate NY and reach as far inland as the northern
Appalachians, but snow will generally be on the lighter side with
the upper-level forcing weakening.

WPC probabilities show low-to-moderate chances (30-50)% for 24-hour
snowfall totals >4" over the heart of MI's Upper Peninsula.
Localized totals >6" are likely, especially given the favorable
meteorological drivers that are at play. Many deterministic
members do show a swath of >6" of snow, but given the wide cast of
potential QPF totals and the different placement of the band, it is
leading to greater dispersion in ensemble mean guidance. At this
time, residents from northern MN and northern WI to the MI U.P. and
tip of MI's Mitten should prepare for at least Minor Impacts.
WPC's WSSI-P does show low-to-moderate chances (30-50%) for Minor
Impacts in the Lower MI U.P. and northeast WI. The WSSI-P also
shows low chances (10-30%) for Minor Impacts (hazardous travel
conditions) over western WI and central MN due to ice
accumulations.


...Western U.S. Mountain Ranges...
Days 1-3...

An active weather pattern continues across much of the West as
repeated rounds of Pacific moisture surge onshore and advance
eastward across the Rockies.

An anchored troughing pattern along the west coast of North
America is forecast to continue for several more days. This
anomalous longwave trough, paired with a strong ridge over Mexico,
is supporting steadfast SWrly flow out of the Pacific that is
supplying copious amounts of moisture over the western-third of the
CONUS. As snow over the central Rockies dissipates this afternoon,
an upper-level ridge axis over the Great Basin will slide east
thanks to the approach of a large upper-low west of CA. An
expansive IVT, with moisture originating out of the subtropics,
will surpass 500 kg/m/s and extend almost the full length of the
U.S. West Coast tonight. This moisture plume will be heaviest along
the track of a frontal system (low 980s low west of OR) that slams
into the West Coast tonight and early Saturday morning. While this
system has a good deal of moisture at its disposal, their is a
significant lack of a continental polar (cP) air-mass ahead of the
storm. Still, the combination of upslope enhancement and persistent
500mb PVA when paired with the onslaught of Pacific moisture will
foster mountain snow throughout much of the West this week.

Snow levels throughout CA will initially be in the 7000-9000ft
range ahead of this first system (higher snow levels farther
south), but as subsequent upper- level disturbances approach as
they round the base of the longwave trough positioned off the West
Coast, 500-700mb height falls and CAA should result in snow levels
coming down to the 5000-7000ft late Saturday and to close out the
weekend. Snow levels will be a little lower in the Pacific
Northwest and northern Rockies, but most snowfall will still reside
in the more remote reaches of these mountains ranges with some
welcomed snow to ski resorts in these regions. That said, the
bigger impacts will be in the Sierra Nevada where low SLR's and
steadily lowering snow levels should prompt heavy snow for many of
the mountain range's passes.

Snowfall totals above 6,000ft in the Sierra Nevada, over the next
three days, are likely to range between 2-5 feet with localized
amounts in the higher peaks of the southern Sierra Nevada topping 6
feet. The WSSI is lit up with Major to even Extreme Impacts due to
Snow Amount, with the I-80 portion beginning near Truckee on west
to around mile marker 158, likely to see significant travel
impacts beginning Saturday night and continuing into Sunday.
Farther north, WPC probabilities show high chances (>70%) for
snowfall totals >4" in the Cascades, Olympics, and on south to the
Siskiyou/Shasta mountains of northern CA. Farther east, snowfall on
the order of 8-12" are likely in the Lewis Range, Blue, and
Sawtooth Mountains above 6000ft, the Tetons, Absaroka, and Bear
River above 7000ft, and the Wind River and Uinta/Wasatch above
8,000ft. The Sawtooth, Tetons, Wind River, and Bear River Ranges
all sport high chances (>70%) for snowfall totals >12" with some
localized totals topping 24" expected.


Mullinax/Weiss



$$

= = =
To unsubscribe from WX-STORM and you already have a login, go to
https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email
Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
 * Origin: Capitol City Online (1:2320/105)
SEEN-BY: 1/19 100 16/0 19/10 37 104/119 105/81 106/201 114/10 120/302
SEEN-BY: 123/130 128/187 129/14 142/104 153/757 7715 154/10 30 50
SEEN-BY: 154/110 700 201/0 203/0 218/700 840 220/10 20 30 90 221/1
SEEN-BY: 221/6 360 226/18 30 44 50 227/114 229/110 134 206 275 300
SEEN-BY: 229/307 317 400 426 428 470 664 700 705 240/5832 266/512
SEEN-BY: 280/5003 291/111 301/1 320/119 219 319 2119 322/757 762 326/101
SEEN-BY: 335/364 341/66 342/200 396/45 423/81 460/58 633/280 712/848
SEEN-BY: 902/26 2320/0 105 304 3634/12 5020/400 5075/35
PATH: 2320/105 154/10 221/6 1 320/219 229/426