FOUS11 KWBC 170743
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
243 AM EST Tue Feb 17 2026

Valid 12Z Tue Feb 17 2026 - 12Z Fri Feb 20 2026

...Pacific & Interior Northwest... Days 1-3...

An active period of winter weather expected this week across the
Pacific and Interior Northwest as repeated shortwaves dive through
a longwave trough entrenched across the region.

Increasing southerly mid-level flow downstream of the lead
shortwave which will dive south along the British Columbia coast.
This shortwave will continue to expand southward, with the trough
axis finally moving onshore WA/OR Tuesday night. This impulse will
continue to track eastward into the Great Basin and Northern
Rockies on Wednesday, with a secondary shortwave moving onshore
immediately in its wake. This mid-level evolution will push 500mb
heights down below the 0.5 climatological percentile today and through Wednesday morning, leading to snow levels for which the NBM
suggests will fall below 1,000 feet as far south as northern CA.
The 10th percentile (a better proxy due to steep lapse rates
beneath the cold core trough aloft) dropping to the surface across
most of the area. While the heaviest precipitation is expected
within surges of WAA through mid-week, this is likely to produce
the first light snowfall accumulations down to the valley floors
and lowlands of WA and OR.

For Tuesday, the heaviest precipitation is expected across OR and
into ID, as well as the southern WA Cascades. Here, the IVT will
maximize within the broad WAA plume and within broad mid-level divergence/height falls downstream of the lead shortwave trough.
Additionally, S/SW flow will impinge favorably into the Cascades
for upslope enhancement, with snow levels falling well below pass
levels. This includes potentially down to I-5 through the
Willamette Valley. The heaviest snow is expected above 2,000 ft,
where WPC probabilities are high (>70%) for Tuesday and low (30%)
Wednesday for 4+ inches each day, leading to locally more than 12
inches of snowfall through 00Z/Thursday. This will create hazardous
travel, especially across Santiam, Willamette, and Siskiyou
Passes. Light snow accumulations are expected even onto the coastal
terrain of WA/OR where there exists a 30-50% chance of at least 2 inches.

A brief break in precipitation is expected Tuesday night before
the second shortwave approaches with renewed ascent aloft and
moisture spreading throughout the region. Moderate to locally is
likely, especially across the WA/OR Cascades and surrounding
lowlands as snow levels again fall below 500 ft. WPC probabilities
for at least 1 inch of snow reach 30% even into the Portland, OR
metro area and surrounding Seattle, WA, with an additional 6+
inches of snowfall likely (70% chance) across the southern WA and
most of the OR Cascades.

...California... Days 1-3...

...Multiple days of heavy and disruptive snowfall to affect the
California mountain ranges this week...

A series of potent Pacific storm systems are working together to
direct copious amounts of moisture at the mountain ranges of the
"Golden State". After snow levels steadily fell throughout the
night, today, another round of heavy snow is expected across just
about all of the CA mountain ranges as a second and more amplified
upper level low dives south along the West Coast. This will spike
onshore flow and additional moisture supply on the southern and
eastern flanks of the upper low. Renewed heavy snow will start out
across the northern California ranges Tuesday morning, then spread
south down the Sierra Nevada from Tuesday afternoon through Tuesday
night. Once again, 1-2 inch/hour rates will be common with 3-4
inch/hour rates possible locally. Snow levels will continue to
fall to around 1,000 ft in far northern California (including the
northern coastal range) Tuesday night, around 2,500ft in the Sierra
Nevada, and between 4,000ft and 5,000ft into the Transverse
Ranges. Snow will continue to fall across California's mountain
ranges trough Wednesday as yet another 500mb shortwave trough west
of WA continues to sustain what feels like an endless supply of
Pacific moisture into the Golden State. However, during the day
Wednesday snowfall rates could diminish in most of the mountains
down to light snow or even flurries at times. With the longwave
trough overhead, snow levels could creep down as low as 1,000ft in
central CA and may support minor accumulations down to 1,000ft.

On Thursday a pair of shortwaves, both moving SSE, but one
impacting the Northern California ranges, and the other following
the previous disturbances hugging the coast until it turns inland
over Southern California, will keep moderate snow ongoing along
most of California's ranges. Rates will not be quite as heavy on
Thursday as on previous days. Snow levels will fall in the
Transverse Ranges to as low as 3,500 feet Thursday morning, while
staying between 1,500 and 2,500 feet from the Sierra Nevada north.

California's mountain ranges welcome the snow, although it will
come down fast and furious through mid-week. Through the end of
this discussion's timeframe (12Z Fri), snowfall will be measured
in feet above 4,000ft along the Sierra Nevada. Several additional
feet of snow is forecast along Donner Pass through 12Z Friday and
more snow still to come. The WSSI shows a large swath of Extreme
Impacts (Substantial disruptions to daily life; extremely dangerous
travel or impossible driving conditions, extensive closures) for
elevations generally above 5,000ft, although some Major impacts as
low as 4,000ft are possible. Major to locally Extreme impacts are
showing up in the peaks of the San Gabriel and San Bernadino
mountains, with mostly Moderate-to-Major Impacts (increasingly more
disruptive to travel jumping from Moderate to Major). There are
also likely to be some Major impacts in the Coastal Range of
northwest CA above 2,000ft. Note that there are Minor to locally
Moderate Impacts expected along I-5 around Mount Shasta, signifying
potential travel delays for I-5 in the more elevated terrain of northern CA.

...Intermountain West... Days 1-3...

Pacific moisture ahead of the longwave upper trough off the West
Coast will spill over the Cascades and Sierra Nevada and reach many
ranges across the Intermountain West this week that badly need the
boost in snowpack. With a lack of a frigid airmass ahead of this
healthy moisture source, the bulk of the heavy snow will be largely
confined to many of the taller mountain peaks. The heaviest
snowfall on Monday will reside in the Blue, Sawtooth, Wind River,
Uinta, and as far south as Mt. Charleston and the Mogollon Rim. WPC
72-hour probabilities are high (>70%) for snowfall totals >12" in
these mountain ranges through Thursday afternoon.

On Tuesday, the highly anomalous upper-low off the Pacific NW coast
will help to usher the initial upper low over southern CA east into
the Intermountain West, causing widespread height falls and a
larger plume of Pacific moisture to pass over the Rockies. The
potent closed low then heads inland over the interior NW and
northern Rockies on Wednesday while opening up into a trough,
prompting snow levels to crash and most valleys are likely to see at
least a coating of snow. By Thursday, much of the Intermountain
West will be in a lull between storm systems, as the next in the
series of shortwaves moves across California. Some snow will spill
over into much of Nevada, while areas further east see the snow
stop completely during the day. Snow with the shortwave over
California moves across the Four Corners into Thursday night and Friday.

The bulk of the heavy snow will be observed in mountain ranges such
as the Wasatch, Bear River, Tetons, Uinta, Wind River, Mogollon
Rim, and CO Rockies who are forecast to receive between 1-2 feet
of snow (locally up to 3 feet possible). Expect Minor to Moderate
Impacts, per the WSSI, with travel over passes from the Lewis Range
and Bitterroots to as far south as the Mogollon Rim likely to
contend with hazardous travel conditions. Some Major Impacts are
showing up in the more remote peaks of these mountain regions.

...Northern Plains & Upper Great Lakes... Days 1-2...

A shortwave emerging from the Great Basin will track quickly to the northeast today, reaching the Dakotas later this evening while also
strengthening in the process. As this trough becomes negatively
tilted and expands across the Northern Plains/Upper Midwest, it
will interact with the LFQ of a strengthening subtropical jet
streak arcing from the Desert Southwest to the Great Lakes. This
setup will support surface cyclogenesis Tuesday evening. This low
is then expected to move very slowly through Wednesday before
gradually filling over the western Great Lakes Thursday night.

As this low tracks slowly eastward, it will interact with
impressive IVT surging above the 99th climatological percentile
into Minnesota. The accompanying moisture and theta-e ridge axis
will then wrap cyclonically around the system and lift into a
pronounced TROWAL. The associated synoptic lift, aided by
increasing WAA, will expand precipitation across the northern tier
of the CONUS from far eastern MT through the western Great Lakes.
Periods of heavy snow are likely as strongly sloped FGEN driving
omega into the TROWAL supports heavy precipitation rates. The most
impressive ascent appears to intersect the DGZ, so despite this
being subjectively elevated (nearing 500 mb), it will support heavy
snow rates and dynamic cooling into a column that is initially too
warm to support snow. However, once precipitation changes to snow,
it will become heavy, supported by the WAA/FGEN beneath the TROWAL
and accompanying CSI evident in cross-sections, supporting rates
that will likely exceed 1"/hr at times (>70% chance). These
intense rates will be accompanied by strong and gusty winds,
resulting in widespread moderate impacts (30-60% chance) from ND
through the Arrowhead of MN. It is in this swath of the Upper
Midwest where there are moderate-to-high chances (50-70%) for
snowfall totals >6", including as far east as the northern shores
of MI's Upper Peninsula. Some localized areas of northern ND and
northern MN could see totals approach 12", but it is the MN
Arrowhead that will see as much as 1-2 feet of snow with localized
totals topping 24". The WSSI-P shows moderate chances (40-60%) for
locally Major Impacts (considerable disruptions; dangerous driving
conditions and widespread closures).

Additionally, with the pronounced WAA rotating around the surface
low, an area of freezing rain is also expected, especially from
near Duluth, MN eastward across northern WI and into northern MI
where the warm nose will be most prevalent while surface temps
remain sub-freezing. This sets the stage for a freezing rain/icing
event that could last for over 24 hours in parts of northern WI and
northern MI. WPC probabilities are moderate (40-70%) for at least
1/10 inch of ice, with locally more than a quarter inch possible,
most likely across the tip of Michigan's Mitten.

...Northeast... Day 2...

A strong surface low moving slowly across the Dakotas/Minnesota
Wednesday will remain entrenched within an elongated mid-level
trough extending into the Mid-Atlantic states. Vorticity lobes
downstream of this wave will spread northeast from the Mid-Atlantic
states into the Northeast, before getting sheared to the east as
mid-level flow becomes strongly confluent south of the secondary
shortwave energy crossing Maine and Nova Scotia. The resultant mid-
level PVA and divergence will overlap with a narrow ribbon of
impressive low-level WAA to produce a stripe of heavy precipitation
from Upstate NY through southern/central New England.

This precipitation will expand eastward from the Great Lakes
Wednesday morning, then exiting off the New England coast by
Thursday morning. Guidance is now coming into better agreement on
the placement over 925-850mb layer-averaged FGEN zone over the
southern tier of NY, that is favoring a swath of snow just north
of the FGEN band. Thermally, the antecedent column is marginal to
support wintry precipitation, and it appears any significant
snowfall accumulation will be contained both to higher elevations
above 1,000 ft, and to where the most intense dynamic cooling can
overwhelm the above- freezing low levels. The most significant
accumulations are most likely from upstate NY into western VT where
conditional instability into a DGZ is just supportive enough to
generate locally heavy rates.

This is reflected by WPC probabilities that reach as high as
10-40% for 4+ inches of snow, especially in the Adirondacks and
Greens, with moderate probabilities (40-70%) for >2 inches
covering much of central New England and the northern half of
upstate NY. It is important to note that the WSE mean snowfall for
much of this area remains below the maximum values, so some
locally higher amounts are probable where any banding persists.
South of this axis of moderate to heavy snow, a corridor of icing
exceeding 0.1" is possible (30-50% chance) from the southern shore
of Lake Ontario with low chances (10-30%) for over one-quarter inch.

...Central Plains... Day 3...

Wednesday night, a potent shortwave trough ejecting out of the
Central Rockies will take on a negative tilt as it heads into the
Central Plains. To the north of the 500mb vort max, strong 700mb
Q-vector confluence will focus a narrow area of strong vertical
velocities, coinciding with a pronounced TROWAL forming over the
Sand Hills of NE and southern SD early Thursday morning. While
there is lingering spread in guidance regarding the placement of
this band as it forms as far west as eastern WY and tracks as far
east as the MO River Valley Thursday evening, most guidance agrees
the impressive synoptic-scale support aloft (left-exit region of a
250mb jet streak over head) and strong SErly 850mb WAA will
support heavy snowfall rates. Latest WPC probabilities show
moderate chances (40-60%) for >4" of snow from eastern WY on east
along the NE/SD border and into southeast SD. It is worth noting
there are low chance probabilities (10-30%) for >8" of snowfall in
northern NE and southern SD. Given the strong dynamics and banding
potential, these are the kind of setups where seeing snowfall
totals are low chance over 48 hours out, but are very much within
reason. Residents in the Central Plains should monitor the forecast
from their local WFO closely in the coming days.

Mullinax/Weiss/Wegman
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