193
FOUS11 KWBC 140746
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
246 AM EST Fri Nov 14 2025

Valid 12Z Fri Nov 14 2025 - 12Z Mon Nov 17 2025


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

Modest Atmospheric River (IVT >500 kg/m/s) and high snow levels
above 8-9k feet are expected at the start of the forecast period
throughout the Sierra Nevada, with this AR gradually waning by the
end of Day 1. Meanwhile, an associated upper low churning off the
southern California coast will begin to swing inland on Saturday
and provide an additional surge of moist southerly flow into the
central/southern Sierra. This flow will not be ideally orthogonal
to the Sierra off the Pacific, but the upper low placement
overhead and PWs above the 99.5th climatological percentile per the
18z NAEFS will allow for gradually falling snow levels, ample
lift, and widespread precipitation. Snow levels will once again
start out above 9k feet, but gradually fall to around 7-8k feet by
Sunday morning ahead of another rapidly approaching upper low early
Monday. In total, 1-2 feet and potentially up to 3 feet of
snowfall is possible for parts of the central/southern Sierra
Nevada above 8-9k feet.

The latest WPC 72-hr snow probabilities >12" across the high
terrain of central and southern Sierra are high (80-99%). Snowfall
totals >24" are becoming more likely above 10k ft as well, with
WPC probabilities of 60-90%.


...Interior Northeast...
Days 2-3...

Persistent troughing remains across New England and southeast
Canada to start the period and will be reinforced by a potent
shortwave dropping southeast into the region by Sunday before
deepening into a strong mid-level low through the end of day 3.
This will provide for warm air advection driven precipitation
Saturday night into Sunday as cold low-level air ahead of this
systems produces a CAD setup across northern New England. The
associated surface low is forecast to slide from southeast Ontario
to coastal Maine and allow for the low-level cold air to only very
slow retreat north. A wintry mix with pockets of freezing rain is
most likely to impact the Adirondacks into the Green and White Mts
of VT/NH/ME.

The transient nature of this system should limit the ice threat
somewhat. For this region, WPC day 2 probabilities for at least
0.1" of ice are 30-60% and very low chances (<10%) for more than
0.25". Snowfall will remain the predominant precip type across far
northern VT, NH and into central/northern ME where QPF may also be
limited enough to prevent a major snowfall event, but some heavier
snowfall rates are possible with the initial precipitation onset
when 700 mb fgen is strongest and the mid-level low crosses over
the region. WPC probabilities for at least 6" are between 30-60% in
this region on Day 3, highest across the northern Greens/Whites
and northern ME.

Once this system deepens across southeast Canada Sunday night into
Monday, very strong west-northwest flow will develop across the
Great Lakes and open up the potential for lake effect/upslope snow
into the Interior Northeast. Specifically, a multi-lake connected
snowband is possible extending from Lake Superior, Huron, and Erie
into far western NY and northwest PA given the strong northwesterly
flow. Current WPC probabilities for at least 4" of snow on day 3
across western NY and northwest PA are low (10-20%), but expect
these chances to increase should the synoptic pattern remain
consistent when CAM solutions are available.

Snell



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