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FXAK68 PAFC 041419
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
519 AM AKST Thu Dec 4 2025

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

Key Points:

- Scattered showers lifting up across the Kenai Peninsula towards
the Mat-Su Valley combined with near freezing surface temperatures
have resulted in a glaze to a tenth of an inch of ice accumulation
on area roadways this morning. This will make for an icy morning
work and school commute for the western Kenai up through the Mat-Su
Valley.

- Southern Copper River Basin will likely see several days of light
snow from today and into the weekend, leading to overall
accumulations on the order of 6-12 inches.

- Increasing offshore winds will lead to frigid wind chills
(especially near the Alaska Range) and the potential for blowing
snow.

Discussion:

A large, nearly stacked, low spinning over the southern AKPEN
continues to eject shortwaves north towards Kodiak Island, Kenai
Peninsula, and western Gulf. The most recent wave overnight combined
with broad isentropic lift has resulted is scattered showers
developing from the Cook Inlet east into the northern Gulf. These
showers have been lifting north for much of the overnight period
with the northern edge starting to move into the lower Susitna and
Mat Valleys. Areas of dense fog that started the night along the
Knik Arm has since dissipated as showers moved in. Temperatures have
been holding steady in the low to mid 30s near Homer, near freezing
throughout the Anchorage Bowl, and in the upper 20s for Wasilla and
Palmer area. The result has been another round of freezing rain for
much of the wester and central Kenai Peninsula, Anchorage Bowl, and
lower Mat-Su Valley. Winter Weather Advisories have been issued for
these areas for light icing on roadways making for hazardous travel
conditions for the morning commute. A Winter Weather Advisory has
also been issued for Turnagain Pass down to about Moose Pass where a
mix of freezing rain and light snow could make for icy conditions.

As has been the case for the past week, deterministic model
guidance has been struggling to resolve these systems. Probabilistic
guidance has done slightly better. For the wave this morning,
precipitation has developed farther west and has progressed
farther north than anticipated. However, with the Arctic airmass
oozing south, showers should be limited in northward progress.
The 12Z PANC ROAB once again showed a decent warm layer from just
above the surface to about 3400 feet. Cooler midlevel air will
start to work in, helping to cool this layer a bit later today. As
such, should see rain showers transition over to a rain/snow mix
then light snow by mid to late afternoon. By then, this round of
precipitation should be winding down for western Southcentral but
working into the Southern Copper Basin. However, the Arctic front
will be quickly approaching from the NW this evening, helping to
tighten the baroclinic zone on this side of the Alaska Range.
Given this, wouldn`t be surprised to see a band of light snow
develop from the northern Kenai Peninsula and up through the Mat
Valley and central Copper Basin by late tonight. Snow will linger
for several days over the southern Copper Basin where snow
accumulations of 6-12 inches are possible.

The Arctic front push through Southcentral on Friday with
temperatures rapidly falling from north to south as the Arctic
airmass works into Southcentral. These temperatures will likely be
the coldest so far this season with many areas across
Southcentral seeing temperatures fall below zero. The Copper Basin
could see temperatures fall into the -20s and dangerous wind
chills of -30 to -35 degrees. Lastly, the Arctic airmass will also
result in strong north/south gap winds for the Alaska Range and
typical spots across the southern Southcentral.

- PP

&&


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

As the low pressure system south of the Alaska Peninsula continues
to steadily weaken, winds speeds will begin to similarly slowly
diminish. Drier, and colder conditions have settled over Southwest
Alaska, providing a reprieve from the precipitation, but
introducing a new concern with the incoming colder temperatures.
Through Thursday, lingering showers will affect Bristol Bay, and
much of the Alaska Peninsula as the low pressure system remains
relatively stationed just to the south of Unimak Island.
Northeasterly winds across the Central Bering and Pribilof Islands
have diminished, and will continue to do so as the low slowly
weakens.

Next up is an Arctic airmass pushing into Southwest Alaska from
the north. Temperatures will plummet into the weekend as an Arctic
trough dives into the region. Temperatures will drop below zero
across the Kuskokwim Delta and the Lower Kuskokwim Valley by
Friday night. Another effect of the Arctic trough will be an area
of gusty north to northeasterly winds re-initiating off of the
Kuskokwim Delta. These winds will reach gale to storm force in
strength and will stretch all the way down to the Aleutians.
Stronger gap winds out of favored southern channels in the
Aleutians are likely with these winds by Saturday. A consequence
of these offshore winds is the threat of extreme freezing spray
from Nunivak Island to Cape Newenham. A Marine Weather Statement
has been issued for Saturday through Tuesday detailing this
threat. Another consequence of the gusty winds and very cold
temperatures is wind chill. Wind chills could dip below -35F in
the Kuskokwim Delta by Saturday night into Sunday. Looking ahead,
it seems like the Arctic air mass will persist into next week,
potentially allowing for a long period of extremely cold
temperatures.

-JAR/CL

&&


.LONG TERM FORECAST (Days 4 through 7 - Sunday through Wednesday)...

A broad area of low pressure will fill most of the Gulf of Alaska
on Sunday and remain in place through next week. Forecast models
have various differences on when low pressure breaks down and
moves out of the Gulf. To the west, high pressure will persist
over the Bering while a weaker front systems track south of the
Aleutians. As has been advertised, beginning on Friday a
significant outbreak of colder air is forecast to spill out of
Canada and into interior Alaska, eventually reaching the eastern
Bering and Alaska Peninsula on Sunday. Cold temperatures are
expected to remain in place through early next week, with cold air
over the Alaska Peninsula to wrap back into the Gulf of Alaska
Sunday into Wednesday. Strong winds out of the interior are
forecast and there is potential for high winds into Southwest
Alaska. The strong northeasterly flow of colder temperatures atop
warmer Bering Sea waters will also promote ocean effect snow
showers for parts of the Aleutian Chain and Alaska Peninsula.
Meanwhile, the denser cold air over Southcentral will increase gap
winds through the usual locations and into the Gulf of Alaska.
With the colder temperatures, areas of snow will be possible for
numerous locations, but nailing down the when and where will
require further analysis of newer model data. The BLUF, it`s going
to be colder; there will be wind through the gaps; and snow
chances will continue to increase through the middle of next week.
Stay tuned.


-BL

&&
.AVIATION...

PANC...VFR to MVFR conditions are expected through the forecast
period. Light freezing rain is expected to become a mix with snow
by 18Z, then switch to all snow by 00Z Friday as weak northerly
flow brings in colder air. Accumulation is expected to be less
than one inch through 00Z Saturday.

&&


$$