Gale Warning 871, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
454 AM AKST Sun Dec 21 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA
(Days 1 through 3: Today through Tuesday)...

Key Messages:

-Strong winds through the Matanuska Valley, Anchorage, Valdez and
 Thompson Pass are peaking this morning and are on track to
 steadily diminish today.

-Very cold temperatures will persist through at least midweek.

The well-advertised high wind event is ongoing for a number of
places across Southcentral this morning. A strong upper level
shortwave trough has now progressed into the northern Gulf, where
bands of convective snow showers continue to drift across open
water. A mesoscale band developing over the southern Cook Inlet
has spread some light snow into Kodiak this morning, but the
remainder of Southcentral remains clear and cold. Strong northeast
flow trailing the shortwave passage is supporting an ongoing bora
wind event across the parts of northwest Anchorage, the Mat
Valley, Valdez and Thompson Pass.

Across Anchorage, northerly winds are already beginning to trend
down from their peak intensity, and this trend should continue
throughout the day. The strongest wind gusts observed thus far
around 70 mph near Palmer have come in over the past couple hours,
but a downward trend will soon begin here as well. Expect a
similar story for Valdez and Thompson Pass, where winds again have
likely already reached a peak and are beginning to slowly come
down. High Wind Warnings remain in effect for the Mat Valley,
Valdez and Thompson Pass, along with a Wind Advisory for
Anchorage. However, things are on track for these headlines to
drop off as the day progresses and as winds steadily trend
downwards through this evening.

As northerly winds begin to settle with weakening northerly flow
and a relaxing north-south pressure gradient, very cold
temperatures will return across interior valleys from tonight into
Monday. Lows in the -10s are likely early Monday for the coldest
spots across the Mat-Su, Anchorage and Kenai Peninsula, with -30s
to -40s already entrenched across parts of the Copper Basin
expected to stick around for at least the next day or two. From
Monday into Tuesday, northerly gap winds will tick back up as a
mid to upper level jet streak wrapping around a strengthening
upper ridge out west pushes east into Southcentral. Thankfully,
this setup does not look nearly as supportive for high winds
compared what we are seeing with the ongoing wind event. Gusty
winds will mainly pick back up in and around Whittier, Seward,
Kodiak and Valdez as the day progresses on Tuesday. For the rest
of Southcentral, dry, clear and cold conditions will persist into
midweek.

-AS

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1
through 3: Today through Tuesday)...

Satellite imagery shows a front draped across the eastern Bering
from near Nunivak Island and extending NNW into a low in the Chukchi
Sea. This front will gradually push into the Y-K Delta this morning
before gradually dissipating this afternoon. Light snow rates and
totals of less than 2 inches are expected to spread across Nunivak
Island and the western Kuskokwim Delta. Only minor accumulation is
expected east of the Kusko River before the front shears apart.

This system will be quickly followed up by a more potent trough,
pushing into the coast by early Monday morning. This system will be
organized enough to persist beyond the coast and push snowfall
further inland. Snowfall lingering around Southwest will result in
total snow accumulations of 2-4 inches across Southwest Alaska
through Tuesday morning. Inland areas near Aniak and Sleetmute to
see slightly less accumulations.

Temperatures will begin to trend warmer with each subsequent front
or wave bringing slightly warmer air and enough wind to mix the
lower-levels into the region through midweek. The majority of the
Aleutian Chain will remain unaffected by the passage of these
troughs, with the ridge axis continuing to promote inactive weather
with southerly winds for the western Aleutians, and northwesterly
winds for the eastern Aleutians through Tuesday.

-Brown/CL

.LONG TERM FORECAST (Days 4 through 7: Wednesday through
Saturday)...

A strong upper level ridge will slowly drift east to keep much of
the AKPen and southern Alaska mainly clear, cold, and dry through
Wednesday into Thursday. By Thursday night into Friday, a potent
shortwave flattens the ridge as it drives south out of the Arctic
and across the interior before deepening into a closed low over
southern Alaska and the northern Gulf by the weekend. This trough
will bring increased chances for snow across Southwest Alaska, the
Copper River Basin, and mainly along the northern/interior side
of terrain across Southcentral for mid to late next week. As this
system progresses south into the Gulf, it brings a renewed threat
for strong northerly winds late next week across typical
locations, including the Matanuska Valley, Valdez area/Thompson
Pass, and along the southern AKPen and Gulf coast. Temperatures
remain below average across Southcentral Alaska, with the coldest
area being the Copper River Basin, where ambient temperatures will
hover in the range of 20 to 40 below zero. Southwest Alaska will
trend warmer through midweek as relatively warm, moist air rides
up and over the ridge, while the western Bering and Aleutian Chain
remains fairly showery and breezy as the ridge nudges east.
Following the passage of the trough late next week, northerly flow
and much colder temperatures are reestablished across Southwest
Alaska while a stronger ridge builds back across the Bering Sea by
next weekend.

&&
.AVIATION...

PANC...VFR conditions expected to persist through the period.
Northerly winds will begin to decline after 18Z Sunday. Winds
turn more out of the north-northwest after 00Z Monday though
continue to decrease.

&&