586
FXAK68 PAFC 311323
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
523 AM AKDT Sun Aug 31 2025

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

Key Messages:

 - Flood Warnings and Advisories remain in effect across Susitna
Valley. Most rivers have, or are currently cresting, and are
expected to fall over the next several days.

 - Labor Day Weekend: Mild with a chance of light rain Sunday and
Monday afternoons for western portions of Southcentral. Localized
breezy areas in the afternoon and evening.

Discussion:

This mornings water vapor imagery shows a broad ridge stationed over
the Gulf with a shortwave trough moving through interior Alaska and
another shortwave lifting towards Nunivak Island and the Southwest
coast. Several more shortwaves can be picked out rotating around the
large low spinning over the Bering Sea. A nice fetch of tropical
moisture is being drawn up between the Gulf ridge and the Bering
low...funneling towards the eastern Aleutians, AKPen, and Bristol
Bay. A shortwave trough is starting to organize near Unalaska and
will be the next system to lift north towards Nunivak Island through
early afternoon. Widespread rain will move into Bristol Bay then
along the southern Alaska Range, spilling over into the Susitna
Valley by this evening. Models still have some disagreement with the
exact position of the rain axis. The NAM moves the rain in slightly
faster with rain moves in further east. The GFS is a bit slower and
keeps the main precip axis along and just west of the Alaska Range
due to having the trough digging deeper over the AKPen on Monday.
Light rain will spread into the Susitna Valley Monday night into
Tuesday as this next trough lifts north. Most of the rivers have
crested as of this morning, but could tick back up with additional
rainfall.

In addition to the light rain, there will be some areas that will
experience breezy conditions as each of these shortwaves moves
through the region. While the Copper Basin should remain generally
dry the next few days, the northern part of the basin could see some
scattered light rain showers work in from the west tonight and again
Monday night. The southern half of the Basin should see some of the
cloud cover scour out today. Bufkit model soundings do indicate more
of a inverted-V sounding profile late this afternoon resulting in
dryer low levels and breezy south winds.

- PP

&&

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

The forecasted atmospheric river event is in progress across
Southwest Alaska this morning. The culprit, a south-to-north
oriented front draped over the Alaska Peninsula, sits nearly
stationary between a deep occluded low over the Bering and high
pressure situated over the Gulf of Alaska. Rainfall has been
steady from the Alaska Peninsula up into the Kuskokwim Delta and
Kuskokwim Valley, and this should persist into Monday.

Very little has changed with the overall forecast and a
hydrologic outlook for the region covers expected rainfall totals
well through Monday afternoon:

* Togiak/Twin Hills: 2.5 to 4.0 inches.

* Dillingham: 2.0 to 3.0 inches.

* Manokotak: 2.5 to 4.0 inches.

* Clarks Point: 2.0 to 3.0 inches.

The main concerns with expected rainfall will be for higher than
normal river and stream levels, as well as water inundation and
ponding of water for low-lying areas.

Otherwise, widespread small craft winds will persist across the
Bering on Sunday, eventually tapering off later this evening.
Gales have been noted through the bays and passes around Cold Bay
with gusts up to and over 50 knots possible. This should hold true
through noon today, with the stronger gusts also diminishing over
the latter half of the day today. Winds for Bristol Bay should
become offshore and gusty as the low approaches from the south,
with northerly gap winds increasing through the Alaska Peninsula.

Conditions take a temporary reprieve on Tuesday morning as the
Bering front finally pushes into interior Alaska and the deep low
over the Bering lifts into the Bering Strait as an open-wave
trough. This should allow for rain to come to a halt over
Southwest Alaska for much of the day on Tuesday. A new system,
however, is forecast to lift into the Aleutians and Alaska
Peninsula from the North Pacific midday Tuesday. This will see
rain chances quickly return to Southwest Alaska Tuesday night and
Wednesday. Additionally, gusty offshore winds are anticipated over
Bristol Bay with northerly gap flow developing through the Alaska
Peninsula as the low approaches from the south.

BL

&&

.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 where
as 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 with
high clouds preventing fog formation this morning. Winds will
remain light and variable, with a southerly component at times,
today and less then 10 kts. Winds turn southeasterly this evening
but remain at 10 kts or less. The best chance for a few southeast
gusts to work in over the terminal looks to be tonight into
Monday morning. The core of strongest southeast winds and gusts
will remain over Turnagain Arm.

&&


$$