034
FXUS21 KWNC 032015
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST December 03 2025

SYNOPSIS: Mid-level low pressure across the northeastern Pacific and Alaska
along with mid-level high pressure over the Bering Sea and western Alaska are
expected to entrench very cold air and dangerous wind chills across central and
southern Mainland Alaska, along with episodes of high winds across southern
Alaska from the Aleutians into Southeast Alaska. This mid-level low pressure is
anticipated to enhance moist Pacific flow across the northwestern Contiguous
U.S. (CONUS), bringing increased chances of heavy precipitation, heavy
high-elevation snow, and high winds early week-2 to this area. Farther east,
surface low pressure exiting the Northeast could bring a swath of heavy snow to
part of the region, with cold high pressure in its wake increasing the chances
for lake-effect snow squalls and high winds over parts of the Great Lakes,
Northeast, central Appalachians, and mid-Atlantic.

HAZARDS

Moderate risk of much below normal temperatures for most of central,
east-central, and southeastern portions of the Alaska Mainland, Thu-Sat, Dec
11-13.

Slight risk of much below normal temperatures for much of central and southern
AK, Thu-Sun, Dec 11-14.

Slight risk of high winds across southern Alaska from Southeast Alaska through
much of the Aleutians, Thu-Wed, Dec 11-17.

Moderate risk of high winds for the Pacific Northwest east to the northern
Rockies, Thu, Dec 11.

Slight risk of high winds, northern and central Rockies and adjacent High
Plains, northern Great Basin, and the Northwest, Thu-Fri, Dec 11-12.

Slight risk of heavy precipitation across much of the Pacific Northwest,
northern Intermountain West, and northern Rockies, Thu-Fri, Dec 11-12.

Slight risk of heavy snow across the Cascades, Thu-Fri, Dec 11-12.

Slight risk of heavy snow across the northern Rockies and adjacent High Plains,
Thu-Fri, Dec 11-12.

Slight risk of heavy snow across the Upper Peninsula of Michigan, the lee side
of Lake Michigan, and adjacent areas, Thu-Sat, Dec 11-13.

Slight risk of heavy snow across portions of the interior Northeast and central
Appalachians, including the Lee of Lakes Erie and Ontario, Thu-Sat, Dec 11-13.

Slight risk of high winds for the Great Lakes, Northeast, and northern portions
of the mid-Atlantic, Fri-Sun, Dec 12-14.

Flooding possible across the Pacific Northwest.

DETAILED SUMMARY

FOR SATURDAY DECEMBER 06 - WEDNESDAY DECEMBER 10:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR THURSDAY DECEMBER 11 - WEDNESDAY DECEMBER 17: The 0z ECENS, GEFS, and
Canadian ensemble means all depict anomalous 500-hPa troughing across the East,
moving into the Atlantic through the first half of week-2. A potent shortwave
is expected to traverse the Northeast early in the period, which may bring a
swath of heavy snow to portions of the Northeast. Models have not been
consistent in handling this feature, and there remains a lot of uncertainty and
model spread regarding the location of heavy snowfall, if any occurs. Cold
surface high pressure should track into the Great Lakes and the eastern CONUS
in the wake of the surface low pressure, with the gradient between these two
systems possibly triggering periods of high winds over much of the northeastern
quarter of the CONUS. In addition, the high pressure system will bring cold air
southward from northern Canada, resulting in potentially low wind chills and a
few days of Lake-effect snow squalls. For these reasons, a slight risk of heavy
snow is posted for areas in the Great Lakes where Lake-effect snowfall is
climatologically favored, and from the central Appalachians into the interior
Northeast, due to the combination of the snow associated with a departing low
pressure system and Lake-effect squalls in its wake. A slight risk for high
winds is posted into the middle of week-2 where the pressure gradient appears
strongest, but no hazard for much below normal temperatures is posted at this
time as wind chills are expected to remain above hazards thresholds. This area
will be monitored for future cold hazards if model guidance trends colder. Only
slight risks are posted due to inconsistencies in the forecast intensity of
these conditions by the various dynamical models and ensembles.



The 0z ECWMF, GEFS, and Canadian ensembles depict an amplified ridge-trough
dipole from west of Alaska through the northeast North Pacific early week-2.
This set-up favors surface high pressure and exceptionally cold air across much
of Mainland Alaska for several days, along with surface low pressure farther
south that may bring high winds along the southern tier of the state. There are
differences in minimum temperature forecasts among the tools, but model
agreement is better than yesterday, and most models are somewhat colder today.
The GEFS and ECENS means keep temperatures slightly above hazards thresholds,
but the Canadian ensemble mean and the dynamical ECMWF, GFS, and Canadian
models all show temperatures dropping below -40 deg F periodically in parts of
central and eastern Mainland Alaska, with isolated areas falling below -50 deg
F. Wind chills are expected to be even lower, and a parallel run of the
Canadian model shows wind chills briefly dropping to between -60 deg F and -75
deg F briefly during the early part of week-2. With better model agreement on
the evolution and intensity of the cold air compared to yesterday, a moderate
risk for much below normal temperatures is included in today`s outlook across
much of central, east-central, and southeastern Mainland Alaska, where models
indicate the lowest temperatures and wind chills. A slight risk of much below
normal temperatures is posted through almost all of central and southern Alaska
into the middle of week-2. The forecast of very cold air along with high winds
along the southern tier of the state increases the threat for extreme amounts
of freezing spray at times near larger bodies of water. Guidance shows
conditions easing as the week progresses, but there is no consensus regarding
how quickly temperatures climb above hazards thresholds in eastern parts of the
Mainland.



The mid-level low pressure near the North Pacific is expected to ease its grip
on the northwestern CONUS a bit more quickly than yesterday, as indicated by
reduced precipitation and snow signals in the Probabilistic Extremes Tools
(PETs). Additionally there is an increase in the disparity among the dynamical
models, a few of which have precipitation out of the Pacific Northwest by the
start of week-2, although this minority solution is an outlier and not
preferred at this time. Since guidance generally shows heavy precipitation
exiting more quickly than yesterday, the moderate risks for heavy precipitation
in western Washington and adjacent Oregon, and for heavy high-elevation snow in
the northern Cascades, have been removed today. However, slight risks for heavy
precipitation and high-elevation snowfall are continued for the first two days
of week-2 very similar to yesterday, with the slight risk of heavy
precipitation risk stretching from the Pacific Northwest through the northern
Rockies, and the slight risk of heavy snow extending along most of the
Cascades, and also the higher elevations in the northern Rockies. The PETs
still show enhanced odds for 3-day accumulated precipitation exceeding 2 inches
early in week-2 from the Washington and Oregon Cascades westward to the Pacific
Coast, with the GEFS snow water equivalent PET depicting enhanced odds for the
3-day amounts approaching or exceeding an inch in the highlighted risk areas.
During the latter half of week-2, multiple models and PETs indicate the
potential for stormy weather to redevelop over part of the western CONUS, but
the models are in poor agreement and inconsistent with their earlier runs
regarding the placement, timing, and intensity of renewed heavy precipitation
The signal for high winds in the PETs remains fairly robust at the start of
week-2 across the Northwest and adjacent sections of the Rockies and High
Plains, although it has stepped back slightly from yesterday. In addition, the
dynamical models and ensemble means favor a pressure gradient relaxing as
week-2 starts. Still, the PETs remain robust enough to justify a moderate risk
of high winds across roughly the northwestern quarter of the CONUS on the first
day of week-2 (Dec 11), with a slight risk of high winds highlighted for a
slightly larger surrounding area continuing through the following day.

FORECASTER: Rich Tinker

$$