Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
329 PM EST Thu Nov 13 2025

Valid 00Z Fri Nov 14 2025 - 00Z Mon Nov 17 2025


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

A strong atmospheric river (AR) is gradually weakening as it
continues to push inland across central California this afternoon,
working its way down the length of the state through Saturday.
This potent (but rather transient) AR is transporting copious
amounts of moisture (PW anomalies well above the 90th percentile),
leading to heavy mountain snows across the Sierras (primarily
above 8k ft) the next few days. After this AR impacts the Sierra
(through Friday), an associated upper-low is expected to become
cut-off from the westerly flow to the north and linger off the
southern California coast on Saturday before swinging inland
Saturday night. This is likely to lead to another burst of heavy
mountain snow across the central/southern Sierra by Day 3.
Uncertainty regarding the timing of this upper low remains a
forecasting challenge, though a trend towards slower inland
progression is looking more likely. The potential for snow levels
to fall to as low as 6-8k ft with the cut-off low on Day 3 is
another complicating factor.

The latest WPC 24-hr snow probabilities >12" across the central and
southern Sierra are highest on day 1 (70-90%), but still peak
rather high (40-70%) on both Days 2 and 3. Snowfall totals >24"
are becoming more likely above 10k ft with WPC probabilities of
60-90% for 72-hr storm total amounts.


...Interior Northeast...
Days 1 & 3...

Persistent troughing continues over the Northeast the next few
days as a series of impulses move through the northwesterly flow
aloft, with a separate and stronger shortwave moving into the
region by late Day 2 into Day 3. These impulses combined with a
renewed cold advection regime blowing across the warm eastern Great
Lakes will result in bands of lake enhanced precipitation through
Friday. This will likely lead to some additional snowfall
downstream of Lake Ontario east of the Finger Lakes into the
Catskills. Cold upslope flow will also lead to persistent snowfall
across portions of the northern Adirondacks, Greens, and higher
Whites of New Hampshire.

The latest Day 1 WPC 24-hr snow probabilities for >4" are moderate
to high (30-80%) and moderate (30-50%) for >8" across the Greens
and higher Whites.

By Day 3, a WAA regime with lingering low-level cold air will allow
for a brief period of freezing rain across the northern Adirondacks
and northern New England. WPC and NBM probabilities for >0.1" of
ice have increased to between 20-40% for this region on Day 3.


Churchill/Snell