934
FOUS11 KWBC 142100
QPFHSD

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

Valid 00Z Sat Nov 15 2025 - 00Z Tue Nov 18 2025


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

The atmospheric river that has brought snow to the Sierra the past
couple of days is winding down this evening, though the relative
lull in wintry weather looks to be short-lived. 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 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, an additional 1-2 feet of
snowfall (and even up to 3 feet locally in portions of the
southern Sierra) is possible above 8-9k feet elevation.

The latest WPC 72-hr snow probabilities >12" across the high
terrain of central and southern Sierra remain very high (80-99%),
and >24" probabilities above 10k feet across the southern Sierra
remain high (60-90%) as well.


...Interior Northeast...
Days 1-3...

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
slowly 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, beginning as early as late in the Day 1 period
(Sunday afternoon/evening).

The transient nature of this system should limit the ice threat
somewhat. For this region, WPC 24-hr probabilities (18z Sun - 18z
Mon) for at least 0.1" of ice generally range between 30-60%
(though are now as high as 75-95% for portions of the Adirondacks
in Essex County) and very low chances (<10%) for more than 0.25"
(but as high as 10% in the Adirondacks). Snowfall will remain the
predominant precip type across far northern NY, 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 8" are between 30-60% in this region
through Day 3, and locally are as high as 80% highest across
portions of 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. The latest WPC probabilities for at least 4" of snow across
portions of western NY and northwest PA have increased to 20-40%,
but expect these probabilities may continue to increase with the
addition of future CAM solutions.

Churchill/Snell






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