Gale Warning 648, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
441 PM AKDT Tue Oct 21 2025

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

A deepening triple point low sits at the southern periphery of the
Gulf of Alaska, while upper-level ridging extends west from
Yukon/Southeast Alaska over Southcentral Alaska, where conditions
are relatively calm this evening. Between these two features lies
a weak surface trough lifting across the north Gulf coast,
producing light rain showers. The low in the southern Gulf
intensifies tonight, becoming a compact, dynamic system with storm
force winds as it tracks gradually northwest. It pushes a strong
front to the north Gulf coast tonight, which will bring increasing
precipitation intensity along the coast. At the same time
northerly gap winds will intensify, including through Thompson
Pass. Precipitation will be showery in nature, with temperatures
below freezing as colder air is drawn out of the Copper Basin,
leading to the potential for some intermittent blowing snow, with
visibility potentially below one mile at times, in the morning
hours of Wednesday. The front lifts inland through the morning and
warmer air will begin to work north, leading to diminishing winds
and improving visibilities. In the Copper River Basin, there will
be a chance for light snow showers as the front lifts through.

Northerly gap winds along the coast increase again Wednesday
afternoon/evening as the compact but at this point, decaying,
occluded, but still deep low tracks into the northwestern Gulf and
strengthens coastal pressure gradients. There is still some
uncertainty in the low track, however, and a more easterly track
would lead to a variation in timing and location of strongest
winds and potential for precipitation. Confidence is fairly high
on a track heading into the Kenai Peninsula Wednesday night,
however, which would push a corridor of gale force winds into
Prince William Sound. The primarily geostrophic flow pushing
through Turnagain Arm as the low tracks south of Seward will favor
some moisture making it past the coastal mountains, especially
combined with some upper-level forcing from the lifting shortwave.
Cloud cover and southeasterly flow will keep low temperatures
from falling much below the mid 30s, so rain is expected to be
favored around the Cook Inlet region, but some snow mixing in
cannot be ruled out especially when precipitation falls overnight
(during the day, snow will be unlikely as temperatures will be
warmer). Exact timing and placement of the precipitation remains
low confidence at this time. Along the coast, precipitation
reaches its heaviest Wednesday evening into the overnight hours.
Through Wednesday night, this is likely to bring Thompson Pass 4
to 8 inches of snow, while most other locations along the road
system see primarily rain. The main exceptions to this are likely
to be along the Glenn Highway near Tahneta Pass and in portions of
the Copper River Basin where precipitation works past the coastal
mountains, which could see some light snow accumulations.

Heading into Thursday, a broad upper level trough continues to
linger across the Gulf of Alaska and Southcentral. With weak
upper level forcing, timing winds or precipitation will be further
complicated by another low from the North Pacific moving into the
Gulf Thursday, and a trough from southwest Alaska sinking into
the western Gulf. Overall, a generally persistent weather pattern
is setting up for the latter half of this week. Generally weaker
flow across the coastal mountains will allow for periods of light
precipitation at inland locations with continued rainfall along
the coast as low pressure lingers in the northwestern Gulf. Each
feature embedded in the upper level pattern will play a key role
in the enhancement of the precipitation and wind outcomes for the
rest of the week.

Quesada/Rux

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(Days 1 through 3: This afternoon through Friday evening)...

The first Aleutian low, yesterday, is now beginning its move into
the Gulf of Alaska this afternoon. The second low in this sequence
is now impacting the Central Aleutians with gusty easterly winds
and rain. This system will continue east-southeastward farther
into the North Pacific by Wednesday morning. The Eastern Aleutians
could be clipped by rain late tonight before the system exits.

Across the southwestern mainland, an upper-level low remains
across the Kuskokwim Delta Coast this afternoon. This feature is
going to interact with upper-level shortwaves rotating around the
low in the Gulf Wednesday morning through Thursday morning. The
result will be a swath of light snow snow from Aniak southward
through Bethel and along the Kuskokwim, Kilbuck, and Ahklun
Mountains. While Aniak to Bethel can expect around an inch of
accumulation with this system, higher amounts remained confined to
the mountain ranges. A shortwave rotates around an upper-level low
in the North Pacific for Friday morning and moves across lower
Bristol Bay and the upper Alaska Peninsula (AKPEN). The airmass
will be cold enough to support snow across areas from Pilot Point
north to King Salmon and Dillingham. However, there are still
question about the strength of this particular shortwave and if it
will provide enough lift to generate precipitation, therefore,
left chance PoPs from King Salmon to Pilot Point for Friday
morning.

Meanwhile, cold northerly flow ensues across the eastern Bering
Sea, Eastern Aleutians, Pribilof Islands, and AKPEN this
afternoon through much of Friday before a weak ridge builds in.
Within this cold and unstable airmass, showery rain/snow mix will
be likely across the AKPEN, especially at night Wednesday and
Thursday nights with max cooling. During the day, expect more rain
and less rain/snow mix. Saint Paul has already recorded their
first flakes of the season today and are currently snowing. Winter
precipitation will continue there into Wednesday morning with a
light accumulation of snow. Another reinforcing shot of cold air
comes in for Thursday morning with more light snow and or
rain/snow mix possible.

A series of shortwaves rounding the base of an upper-level low in
Kamchatka will move into the western Bering by early Friday
morning providing another round of showers for the western
Aleutians. This activity makes it to the Central Aleutians late
Friday morning into the afternoon hours and to the Pribilofs and
Eastern Aleutians by Friday evening. The parent surface low looks
to remain to the west of Saint Matthew Island to near the Gulf of
Anadyr Friday evening.

&&

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

The long term forecast in Southcentral is quite uncertain.
A low in the Gulf of Alaska is expected to bring gusty winds to
gap regions around Kodiak Island on Saturday, but the exact
strength of these winds is uncertain due to a lack in confidence
of the low's position. Precipitation along the Southcentral Coast
is likely with this low. A troughy pattern remains on Sunday,
allowing for lingering rainfall along the coast, but lighter winds
in gap regions. A front pushes into the Gulf of Alaska on Monday,
bringing more precipitation and stronger winds to Kodiak Island
and the Southcentral coast. There is uncertainty in strength and
extent of this front, so winds and rain could be more or less.
Tuesday is where uncertainty reaches its maximum. Some kind of low
is expected in the Gulf, but guidance is all over the place with
its position, strength, and size. Details will be clarified as
Tuesday draws closer.

Southwest Alaska has less uncertainty, but solutions do vary to
an extent. A large low centered over the Gulf of Anadyr is
expected on Saturday, with its front bringing line of small craft
winds to the western Aleutians and a wide swath of light
precipitation for most of the Bering, even including the coastal
Southwest Mainland. including the Western Aleutians. The low drops
into on Sunday, allowing for the wide swath of precipitation to
continue as well as small craft winds in the Aleutians. There is
uncertainty on how far the low will drop and winds will vary
depending on its track. Monday sees the low traverse eastward,
potentially bringing gap winds to the Eastern Aleutians depending
on its track. Tuesday sees a front from a Kamchatka low push into
the Bering. The western Aleutians will see gale force winds and
precipitation with this front. The front will push eastward as the
low enters the Bering sometime early Wednesday.

-JAR

&&

.AVIATION...

PANC...VFR conditions will persist. Northerly winds will strengthen
as a strengthening low moves into the Gulf tonight. Generally
expect speeds to max out at 10 kts, but there could be an
occasional brief period of stronger winds.

&&