FOUS11 KWBC 070706
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
206 AM EST Sat Feb 7 2026

Valid 12Z Sat Feb 07 2026 - 12Z Tue Feb 10 2026

...Northeast & Mid-Atlantic... Day 1...

Extreme cold and dangerous wind chills overspread the Northeast
tonight and continue through Sunday with Key Messages in effect
and linked below.

The combination of an arctic cold front current racing through the
Ohio Valley/Interior Mid-Atlantic will combine with a strengthening
low pressure well offshore to produce extremely cold temperatures
and damaging winds for much of the region, with heavy snow for
parts of the area as well.

A shortwave driving the cold front southward will help generate
widespread light snow across New England and Long Island, but total
snowfall amounts are expected to be rather modest. Despite that,
briefly heavy snow rates combined with the rapidly increasing winds
will still result in impacts, especially to travel due to snow-
covered roads and low visibility. The greatest impacts, and likely
more substantial snowfall, is expected from far SW Maine, SE New
Hampshire, and along the eastern Coast of Massachusetts from Cape
Ann to Cape Cod where low-level convergence, onshore flow and
resulting ocean effect snow (OES) and an inverted trough will all
interact to enhance snowfall. There continues to be uncertainty as
to where the heaviest snowfall will occur. However, intense
snowfall rates of 1-2"/hr are possible (30-60% chance) thanks to
intense ascent into a lowering DGZ within the presence of some
instability. WPC probabilities are moderate (50-70%) for 4+ inches
from the Seacoast of NH through the Boston metro area, with locally
more than 8 inches possible (10-30% chance) and as reflected by
significant spread amongst the WSE plumes.

...Pacific Northwest and Northern Rockies... Days 1-3...

Mid-level trough positioned off the Pacific coast will slowly track
eastward today and Sunday, with the primary trough axis finally
pushing onshore Sunday night as a shortwave lifts onshore near the
CA/OR coast. This shortwave will then continue to track east while deamplifying, reaching the northern High Plains by the end of the
forecast period.

This trough evolution will be accompanied by a modest subtropical
jet streak arcing meridionally downstream to provide overlapping
synoptic ascent. This lift will occur into a moistening column as
persistent SW flow ahead of the shortwave/trough axis will provide
a long duration of IVT exceeding 250 kg/m/s, with IVT max
potentially exceeding 500 kg/m/s (50-60% chance) which will lead to
two rounds of heavy precipitation extending from Oregon through
the Northern Rockies. Snow levels within the strongest IVT plume
will be 6000-7000 ft thanks to pronounced WAA, but will steadily
fall to 3000-4000 ft Monday as a cold front, driven by the
aforementioned trough, progresses southeast. This will allow for
heavier and more impactful snow across the Northern Rockies than
what is anticipated in the Cascades due to lower snow levels. 2-day
WPC probabilities indicate the heaviest snow is expected in the
vicinity of Glacier NP in the Northern Rockies where they exceed
70% for 12+ inches, and locally as much as 2 feet is possible in
the highest terrain. Elsewhere, WPC probabilities are high (>70%)
for 8+ inches across the Absarokas and Tetons near Yellowstone NP,
the Blue Mountains of OR, and across the highest peaks of the WA
and OR Cascades.

Weiss

...Extreme Cold 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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FOUS11 KWBC 140832
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
332 AM EST Sat Feb 14 2026

Valid 12Z Sat Feb 14 2026 - 12Z Tue Feb 17 2026

...Cascades... Days 1 & 3...

A broad upper-level troughing pattern off the Pacific NW coast
will continue to supply lingering low-mid level moisture that
allows for light snow through this morning. Snow levels will drop
to as low as 2000-3000ft today and into Saturday evening, bringing
snow to many of the passes over the WA Cascades. Following a lull
in snowfall Saturday night and into Sunday, another surge of
moisture will be supplied by a strengthening 500mb closed-low west
of British Columbia. Sharp height falls and excellent 500mb PVA
will be paired with an influx of 850-300mb mean-layer moisture to
produce periods of snow. Snow levels will plummet to as low as
800ft around the WA Cascades, while 2000 ft snow levels in the OR
Cascades will be more common. While these snow levels are getting
quite low, snowfall totals below 2,000ft in the WA/OR Cascades will
remain light. The heaviest snowfall will reside above 3,000ft
72-hour WPC probabilities show moderate chances (40-60%) for
snowfall totals >4" for both Snoqualmie Pass and Stevens Pass.
Given the long duration but lack of heavy hourly rates, WSSI-P
shows the chances for Minor Impacts are generally on the low side
(20-40%) with Monday having the best chances for some slick travel
conditions at pass level.

...California... Days 2-3...

...Multiple days of heavy and disruptive snowfall to affect the
California mountain ranges beginning Sunday and continuing into next week...

A pair of potent Pacific storm systems will work together to direct
copious amounts of moisture at the mountain ranges of the "Golden
State" starting Sunday. The first upper low west of California will
kickoff this multi-day heavy snow event on Sunday with snow falling
in the higher terrain of the Siskiyou, Shasta, and Salmon
Mountains. By Sunday night the upper low approaches, causing
heights to fall over CA and the strengthening IVT to direct
subtropical moisture at the state. Monday marks the beginning of
heavy snowfall along the Sierra Nevada with snow levels will
generally ranging from 4500ft to 6000ft from north to south
initially, then fall below 3000ft across northern CA as the other
potent Pacific trough approaches from the northwest. In both cases,
the state will be placed ahead of a pair of 500mb jet streaks that
will generate excellent upper-level divergence aloft, along with a
barrage of Pacific moisture and strong topographically-enhanced
snowfall rates. Heavy snowfall is expected as far south as the
Transverse Ranges above 6,000ft with WPC probabilities showing
moderate chances (40-60%) for snowfall totals >8" in the peaks of
the San Gabriel and San Bernadino Mountains.

California's mountain ranges welcome the snow, although it will
come down fast and furious on Monday and continue into Tuesday.
Through the end of this discussion's timeframe (12Z Tues), multiple
feet of snow will have fallen above 6,000ft along the Sierra
Nevada. WPC probabilities show high chances (>70%) for >24" of
snow having fallen along the I-80 pass by 12Z Tuesday and more snow
still to come. The WSSI-P depicts a highly impactful snow event
along the Sierra Nevada with high chances (>70%) for Major Impacts
above 6,00ft, including the I-80 pass. In fact, for the higher
elevations above 8,000ft, the WSSI-P shows moderate chances (>50%)
for Extreme Impacts, suggesting the potential for significant
impacts to infrastructure. Travel will be dangerous to impossible
in the Sierra Nevada into Tuesday. Note that there are also high
chances (>70%) for Minor Impacts for 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 weekend and into early
next week. With a lack of a frigid airmass ahead of this healthy
moisture source, snow will largely be confined to many of the
taller mountain peaks that sorely need beneficial snowpack. The
heaviest snowfall will reside in the Bitterroots, the Lewis Range,
Sawtooth, and the Blue Mountains whee 72-hour WPC probabilities
show moderate-to-high chances (50-80%) for snowfall totals >8".
Localized amounts ranging between 12-24" are most likely to occur
along the remote reaches of the Lewis Range and peaks of the Blue
Mountains. Farther south, most accumulations in the Great Basin,
the Wasatch, Uinta, Mogollon Rim, and CO/NM Rockies will be on the
lighter side. The peaks around Zion Nat'l Park on north along the
Wasatch sport moderate-to-high chances (50-70%) for snowfall totals

4". Otherwise, most mountain ranges are likely to see 1-4" of

snowfall, with additional snowfall still to come on Tuesday.

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

The last 24 hours have seen some model guidance (GFS/ECMWF)
gradually creep north with the precipitation shield. This is due to
the approaching 500mb shortwave over western PA coming in
stronger, thus leading to healthier PVA aloft and more 250mb jet
streak enhancement aloft. While boundary layer temperatures along
I-95 south of Philadelphia remain quite marginal on Sunday,
elevated terrain north and west of the Delaware River are likely to
have better chances to see wet snow Sunday afternoon. As the upper
trough in the Carolinas spawns low pressure over the NC Outer
Banks Sunday evening, 850-700mb WAA to the north of the low will
support narrow banding of snow from eastern PA and northern NJ to
the NYC metro, Long Island, and coastal southern New England. There
remains notable spread in model guidance in the position of this
band, but trends in not only the GFS/ECMWF guidance but also their
AI counterparts are showing additional support for a ribbon of
light snow. WPC probabilities show low-to-moderate chances (30-50%)
for snowfall totals >1" from the Delaware and Lehigh Valleys on
east to Long Island, but probabilities for >2" of snowfall are
<20%, showing that most totals are minor and likely to range
between a coating-2". There is the potential for additional
changes to this forecast in the next 12-24 hours.

The probability of significant icing across the CONUS is less than
10 percent.

Mullinax

$$
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FOUS11 KWBC 150732
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
232 AM EST Sun Feb 15 2026

Valid 12Z Sun Feb 15 2026 - 12Z Wed Feb 18 2026

...Cascades & Olympics... Days 2-3...

On Monday, a strengthening 500mb closed-low west of British
Columbia will slide south and just off the coast through Tuesday.
Sharp height falls and excellent 500mb PVA, combined with an
influx of 850-300mb mean-layer moisture and upslope enhancement,
will produce periods of snow over the Olympics and Cascades. Snow
levels will plummet to as low as 800ft around the WA Cascades and
Olympics, while 2000ft snow levels in the OR Cascades will be more
common. In fact, some of OR's coastal range could see snow to
elevations as low as 1,000ft. While these snow levels are getting
quite low, snowfall totals below 2,000ft in the WA/OR Cascades will
remain light. The heaviest snowfall will reside above 3,000ft
where 72-hour WPC probabilities remain in the moderate range
(40-60%) for additional snowfall totals >4" for both Snoqualmie
Pass and Stevens Pass. Given the long duration but lack of heavy
hourly rates, WSSI-P shows the chances for Minor Impacts are
generally on the low side (20-40%). Impacts are most likely to be a
combination of snow covered roads and reduced visibilities.

...California... Days 2-3...

...Multiple days of heavy and disruptive snowfall to affect the
California mountain ranges beginning Sunday and continuing into next week...

A pair of potent Pacific storm systems will work together to direct
copious amounts of moisture at the mountain ranges of the "Golden
State" beginning today and lasting into the middle of the upcoming
week. A broad positively-tilted upper level troughing pattern off
the Pacific NW coast will supply low-mid level moisture that
allows for light snow through tonight into the higher terrain of
the Siskiyou, Shasta, and Salmon Mountains. The heaviest snowfall
through Sunday are likely to reside above 5,000ft where 1-2 feet of
new snow accumulation are possible at the higher elevations
through Sunday night.

By Sunday night, the upper low approaches, causing mid-to-upper
level heights to fall over CA and the strengthening IVT to direct
subtropical moisture at the state. The state will be placed ahead
of a 500mb jet streak that will generate excellent upper- level
divergence aloft, along with a barrage of Pacific moisture and
strong topographically-enhanced snowfall rates. Monday marks the
beginning of heavy snowfall along the Sierra Nevada with snow
levels initially starting out around 6,000ft from north to south
initially, then falling to as low as 3,000ft by Monday night.
Farther north, snow level will dip below 3,000ft across northern CA
as the other potent Pacific trough approaches from the northwest.
Snowfall rates between 1-2"/hr will be common with some instances
of >3"/hr snowfall rates in the central and southern Sierra
Nevada. Heavy snow is also expected in the Transverse Ranges above 6,000ft.

By Tuesday, another round of heavy snow is expected across just
about all of the CA mountain ranges as a second, strong upper
level low dives south along the West Coast, enhancing onshore flow
and supplying additional moisture on the southern and eastern
flanks of the upper low. Snow levels will fall to around 1,000 ft
in far northern California (including the northern coastal range),
around 2,500ft in the Sierra Nevada, and just below 5,000 ft into
the Transverse Ranges with snow continuing to fall across the
state's mountain ranges into Wednesday.

California's mountain ranges welcome the snow, although it will
come down fast and furious both Monday and Tuesday. Through the
end of this discussion's timeframe (12Z Wed), multiple feet of
snow will have fallen above 5,000ft along the Sierra Nevada. WPC
probabilities show high chances (>70%) for >30" of snow having
fallen along the I-80 pass by 12Z Wednesday 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 6,000ft, although some Extreme impacts as low as 5,000ft 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). Note that there are also Minor to
locally Moderate Impacts 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 today and into the upcoming
week. With a lack of a frigid airmass ahead of this healthy
moisture source, snow will largely be confined to many of the
taller mountain peaks that sorely need beneficial snowpack. The
heaviest snowfall will reside in the Bitterroots, the Lewis Range,
Sawtooth, and the Blue Mountains where Farther south, most
accumulations in the Great Basin, the Wasatch, Uinta, Mogollon Rim,
and CO/NM Rockies will be on the lighter side. The peaks around
Zion Nat'l Park on north along the Wasatch sport moderate-to-high
chances (50-70%) for snowfall totals >4". Otherwise, most mountain
ranges are likely to see 1-4" of snowfall through Monday.

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 footprint of Pacific moisture to track through the Rockies.
Snow levels will lower to the valley floors in western Mt and
northern ID, with some light snow possible even in the Salt Lake
City area. Still, the lack of a frigid airmass at the surface will
keep the bulk of the heavy snow in the mountains with ranges such
as the Wasatch, Bear River, Tetons, Uinta, and Wind River seeing
locally heavy snowfall along their peaks. Many of the CO ROckies
will also receive snowfall, but the heavier amounts >8" will be
confined to elevations above 9,000ft.

72-hour WPC probabilities show high chances (>70%) for snowfall
totals >8" for most of the Intermountain West's ranges, but the
locally heavier total's (>12") are most likely to occur in the
peaks of the Lewis Range, the Bitterroots, Sawtooth, Blue, Bear
River, Wasatch, and Uinta.

...Upper Midwest & Great Lakes... Day 3...

By 12Z Tuesday, the remnant yet vigorous trough that was originally
over southern CA late Monday will race across the Rockies and
project excellent 500mb PVA over the northern High Plains. The
ECMWF SATs shows a roaring 150kt 200mb jet streak (wind speeds
topping the 99.5 climatological percentile) over the Southwest will
place its divergent left-exit region over the Great Plains. With
the aid of lee-side downsloping and low-level WAA across the
Plains, an exceptionally deep surface low will form over southern
MT that reaches as low as 980mb Tuesday morning, or MSLP values
that are below the 1st climatological percentile. As WAA ahead of
the warm front reaches across the Upper Midwest, strong isentropic
ascent will ensue as the warm/moist air runs into a colder/drier
air-mass over northern ND and northern MN. Precipitation initially
starting as rain Tuesday afternoon will changeover to snow over
northeast MT, northern ND, and as far east as the MN Arrowhead
Tuesday night. Meanwhile, from northern MN and northern WI to the
northern tier of Michigan's Mitten, the overrunning setup would
favor a wintry mix of sleet and freezing rain Tuesday night and
into Wednesday morning. WPC probabilities show low chances (10-30%)
for pockets of over one-tenth of an inch of ice accretion in parts
of northern WI and MI.

There remains a high degree of uncertainty in the storm track, as
well as when the transition to snow would occur. Snow beneath the
strengthening TROWAL over northeast MT and northern ND would
perhaps not only support heavy snow, but the impressive strength of
the cyclone itself would foster blowing snow on its northern and
western flanks.In terms of snowfall, the MN Arrowhead sports low-
to-moderate chances (30-50%) for >4" of snowfall through 12Z Wed.
Most of far northeast MT, northern ND, and northern MN have
moderate chances (40-60%) for >2" of snowfall, but this is an area
where any minor change in duration or placement in the deformation
axis could result in notable changes to the snowfall forecast.
Regardless, the pressure gradient will be tight enough to where all
of these areas have moderate chances (40-60%) for Minor Impacts
(per WSSI-P) due to some combination of snowfall amounts of blowing
snow through early Wednesday morning.

...Northeast... Day 1...

The airmass in the northern Mid-Atlantic and latest guidance
continues to favor areas farther north from southeast PA across
the Delaware River and into NJ and as far east as Long Island for
light snowfall. WPC probabilities show low-to moderate chances
(30-50%) for snowfall totals >1" from the Delaware and Lehigh
Valleys on east to Long Island, but probabilities for >2" of
snowfall are <30%, indicating that most totals are minor and
likely to range between a coating-2" from southeast PA (with
elevation) on east through northern NJ and across the NYC metro.
Snow should peak in intensity Sunday night and conclude by Monday morning.

Mullinax
$$
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