FOUS11 KWBC 130819
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
319 AM EST Fri Feb 13 2026

Valid 12Z Fri Feb 13 2026 - 12Z Mon Feb 16 2026

...Central & Southern Rockies... Days 1-1.5...

A broad upper-level trough lifting northeastward over Baja
California will continue to funnel anomalous moisture into the
Four Corners region today with 500-700mb Q-vector convergence over
the central and southern Rockies. The lack of a continental polar
(cP) airmass is keeping periods of snow confined to elevations
above 8,000ft throughout the Four Corners' mountain ranges today
and into early Saturday morning. 700-500mb height falls, 500mb PVA,
and PWs above the 90th climatological percentile will support
mountain snow as far south as the Gila Mountains to as far east as
the Sangre De Cristo range. The increased upper-level synoptic-
scale forcing will improve snowfall rates in the higher terrain
with >1"/hr rates at times. 48-hour WPC probabilities show
modertae-to-high chances (50-80%) for snowfall totals >4" in the
AZ Gila Mountains and the CO/NM Rockies, with the higher
confidence in snowfall >6" being above 9,000ft. In the peaks of
the CO Rockies and Gila Mountains, there are some low chance
probabilities (<30%) for snowfall totals >8" through Saturday morning.

...Northern New York... Day 1...

A progressive 500mb vorticity max over Ontario Friday afternoon
will provide sufficient upper-level ascent atop a low-level warm
front driven by a narrow sliver of 850mb WAA. Guidance is coming
into better agreement on a period of moderate snow, potentially
falling heavily at times, along the shores of Lake Ontario on east
into the Tug Hill and Adirondacks Friday night. Mean flow out of
the NW with residual 700-300mb moisture will support lingering
periods of snow into the Tug Hill and Adirondacks into early
Saturday morning before tapering off by midday. Most snowfall is
likely to range between a coating-3" for much of northern New York,
although the Tug Hill features low chances (<20%) for localized
amounts >4" through Saturday morning.

...Cascades & Northern Rockies... Days 1-3...

An upper-level trough in the Gulf of Alaska will dive south just
off the coast of British Columbia and direct a plume of rich
Pacific moisture at the Pacific Northwest this afternoon and
into Saturday. A passing cold front and height falls in advance of
the encroaching upper trough will cause snow levels to drop as low
as 2,000ft in the Olympics and Cascades. Elevations in the WA
Cascades above 4,000ft sport the better chances for snowfall
amounts surpassing 6", while most elevations below 3,000ft range
between a coating-3". WPC probabilities for at least 4 inches of
snow for Stevens and Snoqualmie passes are between 40-60%. The
plume of Pacific moisture spills eastward into the Northern Rockies
with the Bitterroots, Sawtooth, and Lewis Ranges most likely to
receive measurable snowfall starting Friday evening and continuing
throughout the day Saturday. The Northern Rockies will remain
downstream of a robust 250mb jet streak and steady 500mb PVA
advection through Sunday as well, keeping snow in the forecast
through the weekend's conclusion. Similar to the Cascades, most
snowfall totals will be minor (coating-3" at the lower elevations.
For the more remote elevations above 5,000ft in the Bitterroots and
Lewis Range, 2-hour WPC probabilities show moderate-to-high chances
(50-80%) for snowfall totals >8" with totals surpassing 12" above
6,000ft in the Lewis Range. Meanwhile, as the passing cold front
will sinks southward over the OR Cascades, snow levels will remain
around 4,000ft with most heavy snowfall staying in the more
remote/volcanic peaks.

...California... Days 2.5-3...

A potent closed 500mb low west of CA will emanate healthy 500mb PVA
over the Golden State as early as Sunday afternoon with diffluent
flow at the nose of a strengthening 500mb jet streak. Increasing 850-300mb
moisture ahead of the trough steadily increases over northern CA
with periods of mountain snow unfolding in the Siskiyou/Shasta. The
500mb low by Sunday night is a robust one, highlighted by 500mb
heights per ECMWF that are below the 1st climatological percentile.
Ahead of the upper low, a 500-750 kg/m/s IVT will direct
subtropical East Pacific moisture northward into the Sierra Nevada
by early Monday morning with snow levels down to 5,000ft. Sunday
night into early Monday morning marks the beginning of a multi-day
barrage of heavy mountain snow throughout much of the Golden State
with heavy snow eventually starting to accumulate during the day
Monday as far south as the Transverse and Peninsula Ranges down to
5,000ft. See WPC's extended range discussion for more information,
but it is worth noting WPC's WSSI-P shows moderate-to-high chances
(50-70%) for Major impacts in the central and southern Sierra
Nevada on Presidents' Day that then jump to >70% for all of the
Sierra Nevada above 6,000ft by Tuesday. Residents and those
traveling through passes in California next week should monitor
the forecast closely in the coming days.

...Central Appalachians & Mid-Atlantic... Day 3...

...High confidence in a moisture-latent storm system, low
confidence in precipitation-type from the Appalachians to the I-95 corridor...

A sharp 500mb trough tracking through the Lower MS Valley early
Sunday morning will tap into ample Gulf moisture and direct it
northeast into the southern and central Appalachians. In addition,
a strong >140kt jet streak southeast of the MA Capes is placing its
diffluent right-entrance region over the Mid-Atlantic, providing
excellent upper-level divergence aloft. Guidance is in good
agreement on a rather strong surface low (sub 1000mb low) tracking
across northern MS/AL that, according to the ECMWF, is highly
anomalous, with the aforementioned pressure being below the 1st
climatological percentile. The integrated vapor transport (IVT)
over the Southeast tops 750 kg/m/s, exceeding the 97.5
climatological percentile, and results in moderate-to-heavy
precipitation moving into the Mid- Atlantic Sunday morning and
through Sunday evening.

While there is no shortage of moisture at this system's disposal,
the cold airmass in advance of the storm is quite marginal. Despite
the presence of high pressure over New England, the temperature
regime associated with this high pressure is not particularly cold
at all. Using a combination of GEFS/EPS percentiles, 10th
percentile temperatures in northern MD are 32-34F, with 50th
percentile values in the mid 30s. Meanwhile, dew points are likely
to range between the upper 20s and low 30s. The resulting wet-bulb
temperatures at the surface tend to hover around or slightly above
freezing in central Appalachians, northern VA, northern MD, and the
DelMarVa Peninsula. With temperatures in the surface-850mb layer
being isothermal along the 0C isotherm to even 1-2C above freezing,
the potential for snowfall will be heavily dependent upon
elevation and dynamic cooling via strong vertical velocities and
heavy precipitation rates. This system is very much more of a
March-like storm system, where mesoscale banding and elevation are
the primary methods for which accumulating snow would occur.

WPC probabilities are not overly impressed at this time with <30%
chances for over 1" of snowfall in the central Appalachians and
northern Mid-Atlantic. Given the lack of a thermally-supportive
boundary layer via marginal wet-bulb temperatures, it will prove
difficult to support a widespread snow event. However, as the event
encroaches upon the hi-res CAMs guidance window, confidence in
whether a narrow swath of measurable snow from the central
Appalachians to the Mid-Atlantic I-95 corridor will come into
better focus. For now, residents in the central Appalachians and
Mid-Atlantic should, at minimum, expect a dreary/wet Sunday with
the potential for some snow mixing in over elevated terrain.

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

Mullinax

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