874
FXAK68 PAFC 310121
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
521 PM AKDT Sat Aug 30 2025

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

Key Messages:

 - Flood Warnings and Advisories remain in effect across Susitna
   Valley, and many rivers still have elevated river levels.

 - Through the remainder of Labor Day Weekend: Generally warm,
   mostly cloudy. Dry through Saturday afternoon, with a chance of
   light rain thereafter. Localized breezy areas.

Discussion:

Overall, fairly benign conditions continue. Expect generally warm
and dry weather to trend a bit wetter through the beginning of
next week as successive shortwave troughs move into Southern
Alaska from the North Pacific. Forecast confidence is high that
any rain that falls will be of low intensity, as the bulk of
rainfall will remain over Southwest Alaska. Forecast confidence is
medium to high that the greatest overall rain amounts will be
focused along Western Susitna Valley, the Western Alaska Range,
and Southern Kodiak Island. Forecast confidence is lowest
regarding the timing of rainfall, as well as far east rain will
extend into Southcentral. By Tuesday, models are signaling that
the ridge currently over Southcentral will weaken and be displaced
enough for a weakening front to push into the Talkeetna and Kenai
Mountains. However, models generally tend to overcome ridging a
bit too quickly, so it remains to be seen whether this trend will
hold. As it stands, all but the Copper River Basin is forecast to
see some light rain between now and Tuesday afternoon.

In addition to light rain, there will be localized areas of breezy
winds. Confidence is highest for Copper River Valley when it comes
to the timing and strength of winds. For other areas that
typically experience gusty southeasterly winds, such as the
Anchorage and Palmer areas, forecast confidence is much lower as
these localized winds will be much more sensitive to subtle shifts
in the pressure gradient field. If winds do occur for these areas,
they may occur Sunday afternoon and periodically on Monday and
Tuesday, with gusts currently forecast to remain below 20 mph.

-Chen

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA / BERING SEA / ALEUTIANS
(Sunday to Tuesday)...

A deep slow-moving low brings heavy rainfall, fog and strong
winds to the region through Tuesday.

A 980mb low located 200 nm east of Shemya moves northeastward the
next 48 hours. Its effects will be widespread over the Aleutians,
Alaska Peninsula and Southwest Alaska during this time.
Persistent southwest to southerly flow will continue to tap into
atmospheric river moisture resulting in heavy rainfall through
Monday morning. Rainfall amounts as of 4:00pm today range from a
trace to 0.15" from False Pass east to Nelson Lagoon.

This afternoon`s heavy rainfall continues into late Sunday
afternoon from False Pass to Nelson Lagoon and also from
Togiak/Twin Hills to Dillingham as a more southerly flow of
moisture reaches the Alaska Peninsula and coastal areas of
Southwest Alaska. Localized rainfall amounts on the southern side
of the Aleutians and AK Peninsula are likely to record an
additional total of 1.50" to 3.00" of rain during this time
frame. An additional 1.50" to 2.00" of rain to the Togiak/Twin
Hills to just west of the Dillingham area. A brief lull in the
rain is possible tomorrow afternoon though heavy rain returns for
the evening and continues into Monday morning. This second wave of
heavy rain brings an additional 1.00" to 2.00" of rain across the
entire area. Therefore, stream rises and ponding of low lying
areas along the Bristol Bay coastline are possible.

Widespread small craft to gale force strength winds are expected
over most of the region this weekend. This could cause elevated
surf conditions, wave heights between 4 and 8 feet and coastal
flooding. Wind gusts ranging from 30 to 40 mph in the False Pass
to Nelson Lagoon region though gap winds gusting to 55 mph. Today,
Cold Bay`s gusts ranged from 45 to 55 mph with a wind gust just
ahead of the passing front of 62 mph. While not receiving rainfall
amounts as high as coastal areas, inland areas of Southwest
Alaska could record wind gusts between 35 mph and 45 mph this
weekend.


&&

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

The long term forecast is similar to before. A longwave trough
sets up over the Bering while a stout ridge extends from the Gulf
of Alaska through the Alcan Border. This pattern will linger
until next weekend, when the ridge flattens out and allows the
trough to progress eastward.

Tuesday has a front from a north Pacific low move up into the
Alaska Peninsula. This steers the moisture flow from an
atmospheric river directly into the Alaska Peninsula and results
in heavy rain for the region as well as gusty gap winds.
Settlements such as Cold Bay and False Pass could see multiple
inches of rain through Saturday as this area continues to receive
rainfall and gusty winds as multiple fronts and lows move in from
the west. There is some uncertainty with the exact orientation of
the atmospheric river, so drier or wetter scenarios are possible.
Meanwhile, inland areas of Southwest Alaska will initially be dry
before the moisture plume pushes inland on Wednesday. Just like
the Alaska Peninsula, multiple fronts will push inland, bringing
multiple rounds of rainfall all the way through Saturday.

Southcentral is a completely different story. Apart from a front
that may bring rainfall to Kodiak Island and the Alaska Range on
Tuesday, the ridge will be present over the Gulf of Alaska at the
start of the long term on Tuesday. This means that drier
conditions as well as calmer winds will be prevalent. This
pattern will continue through Thursday. Friday is where things get
uncertain. Some guidance has a low move up the Gulf, bringing
heavy rains along the Southcentral coast and Kodiak Island whereas
others don`t have this happening. There is some more agreement on
Saturday when the ridge flattens out and the trough out west is
able to move eastward. Heavy rains and gusty winds will follow
with some uncertainty on their exact placement.

-JAR

&&


.AVIATION...

PANC...VFR conditions will persist through the TAF period.
Southeast gusts of 12 to 18 kts could clip the terminal at times
tonight through Sunday morning. However, the core of strongest
winds will remain over Turnagain Arm. High clouds should prevent
fog formation tomorrow morning.

&&


$$