Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
353 PM EST Fri Nov 13 2026

Valid 00Z Sat Nov 14 2026 - 00Z Tue Nov 17 2026


...Appalachians and Northeast...
Days 1-2...

An upper low over the Northeast will drift east to Atlantic Canada
through Saturday night. The coastal surface low, currently south of
Long Island, will continue drifting east through this evening.
Further precipitation over the region through Sunday will come
from back side forcing over the Great Lakes and upslope areas in
interior terrain. Lake effect snow is quite limited with warming
thermals advecting in from the north tonight. Ongoing lake effect
precip is mainly rain/slushy snow with no Day 1 snow probs for >2"
from the Great Lakes.
Upslope snow continues over the central/southern Appalachians
tonight in NWly flow. Day 1 probs for >2" are 30-40% in central WV
and 40-60% in the highest Smokies.
The more appreciable snow is for western/northern slopes of the
Adirondacks/Greens Saturday/Saturday night ahead and with a mid-
level low center tracking south from Quebec late tonight through
Saturday night. Day 1.5 (12Z Sat-12Z Sun) probs for >4" are 20-60%
for the northern Adirondacks and Greens.


...Western United States...
Days 1-3...

An active pattern continues through midweek for the West Coast with
a series of troughs and atmospheric rivers (ARs) coming ashore.

A trough pushing into northern CA now has a pre-frontal swath of
moisture/precip approaching the Sierra Nevada where snow levels
are around 7500ft. These levels drop to around 6000ft during the
main precip with the SPC REFS depicting mean hourly snow rates of
2-3" working south down the length of the Sierra Nevada through
about 04Z.

The mid-level trough axis crosses Nevada tonight with snow levels
of 7000-8000ft and becomes quite sheared as it crosses Colorado
Saturday with snow levels around 8000ft. Day 1 snow probs for >6"
are 40-80% for all Utah ranges south from the central Wasatch, and
the San Juans of CO/NM into west-central CO ranges/mesas. Precip
shifts to the southern Plains by late Saturday night.

The next AR/cold front ahead of a trough reaches the PacNW coast
Saturday afternoon with a slow dig south over CA then through
Monday with only a little inland progression. Day 2 snow probs for
>6" are 30-50% for the length of the WA/OR/northern CA Cascades/
Klamath above the snow levels of 6000-7000ft.

The southward progressing AR shifts down the length of the Sierra
Nevada Sunday night through Monday with snow levels dropping from
7000-6000ft as the precip occurs. Day 3 snow probs for >6" are
40-70% for the northern and central Sierra with probs decreasing
for the southern sections as a positive tilt to the trough on
Sunday night becomes more neutrally tilted on Monday, allowing a
more progressive push inland by the time the precip reaches the
southern Sierra Nevada.


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


Jackson