859
FXAK68 PAFC 291252
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
452 AM AKDT Fri Aug 29 2025

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

Key messages:

 - An atmospheric river continues to move across the eastern half
   of Southcentral this morning. Flood Watches remain in effect
   for the eastern Kenai Peninsula and the Susitna Valley. A Flood
   Warning remains in effect for the Yentna River above Lake
   Creek. A Flood Advisory is in effect for the Anchorage Bowl and
   Seward and Bear Creek Neighborhoods until 10 AM this morning.

 - Strong gap winds will continue across the Copper Basin through
   this afternoon. Gusty southerly winds will also redevelop over
   Cook Inlet this morning, with gusts to 40 mph expected from
   Homer to Anchorage. A Special Weather Statement is out for
   portions of the Copper River Basin, the Copper River Valley,
   and the Western Kenai Peninsula.

 - Rain and strong winds will end from west to east through this
   evening as quieter conditions return for the start of the
   weekend.

Discussion:

A very active pattern remains in place across Southcentral this
morning as an atmospheric river continues to move east toward
Prince William Sound and a strong frontal system moves over Cook
Inlet. While the heaviest rain is moving east of Cook Inlet, bands
of moderate to heavy showers are developing continue to stream
over Cook Inlet, Anchorage Bowl, Mat-Su, and western Kenai
Peninsula just out ahead of the front. The persistent rainfall has
elevated numerous creeks and rivers across the area.

Overall, the forecast today through the weekend remains on track.
The main upper trough off to the west will amplify and accelerate
northeast into the Copper River Basin by Friday afternoon, while
the main moisture tap and front sweep across Southcentral from
west to east. Cooler, drier air will advect into the region with
the frontal passage. A colder airmass advecting into the region
through Kamishak Gap, along pressure rises behind the front, will
usher strong southwesterly winds up the Cook Inlet this morning,
persisting into much of Friday. Gusts of 30 to 45 mph are not out
of the question from Homer north to Kenai, with the peak expected
around mid- to late-morning Friday. Gusty southwesterly winds
will also develop over at least West Anchorage through Friday
evening. Periods of rain will end from west to east through Friday
evening as the front and upper trough progress steadily northeast
with time. Ahead of the trough passage, cooling air aloft coupled
with daytime heating over the Copper Basin could yield a few
thunderstorms on Friday afternoon as the air mass briefly becomes
more unstable.

Behind this system, expect clearing skies by Friday afternoon and
evening. Low temperatures overnight Friday into early Saturday
morning could dip into the 30s for some sheltered locations if
winds become calm. Saturday again looks to be much calmer and
quieter as the upper level ridge rebounds overhead. Cloud cover
and rain chances will begin to increase somewhat from late
Saturday into Sunday ahead of a strong low pressure and frontal
system moving over Southwest. Right now, it looks like the best
rainfall chances will stay confined to the Alaska Range and
northern Susitna Valley, but this will depend on how far the front
along with a returning moisture axis is able to work into
Southcentral through Sunday evening.

-AS/TM

&&


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

Light and scattered rain showers across the Kuskokwim Delta early
this morning have diminished with partially clearing skies and
pockets of low stratus elsewhere across Southwest Alaska as the
longwave trough axis pushes through the region. The clearing skies
along with cold air advection overnight has allowed temperatures
to drop into the upper 30s across much of Southwest Alaska. Drier
conditions and periods of sunshine are expected through today
across the southwest mainland as weak, transient ridging moves
over the region.

Further west, a dynamic 982 mb low enters the western Bering this
morning as its gale-force front tracks across the central Bering
through this morning into this afternoon. Widespread moderate to
heavy rainfall and low end storm-force gusts along the front are
expected across the Central Aleutians today before peak wind gusts
gradually weaken back to gale strength as the front pushes over
the Eastern Aleutians and Pribilof Islands this afternoon. The
front reaches Southwest Alaska by early Saturday morning, bringing
an end to the brief period of quiet weather.

Another potentially prolonged rainfall event is in store for much
of Southwest Alaska as rain initially reaches the Kuskokwim Delta
and Western Capes on Saturday morning before becoming more
widespread across Southwest Alaska through Saturday evening. Deep
southwesterly flow transporting ample moisture out of the North
Pacific and the front stalling near the coast will again allow for
multiple rounds of rainfall across Southwest Alaska and the
southern AKPen through the weekend into early next week.
Persistent southerly flow in the eastern Bering pushing small
craft to gale-force winds into the northern Kuskokwim Bay may
produce areas of increased surf at times, though the chance for
coastal flooding remains low at this time but will continue to be
monitored.

&&


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

At the beginning of next week, a broad longwave trough will be
situated over the western and central Bering Sea, while a longwave
ridge extends up from the North Pacific into the Gulf of Alaska
toward the Alcan Border. This general pattern looks to hold
through mid-to-late week, aiming a stream of tropical moisture in
excess of one inch of precipitable water between these features,
toward the Alaska Peninsula and Southwest Alaska. As a result,
several inches of rainfall are forecast along the Pacific side of
the Alaska Peninsula, potentially in excess of 4 inches for some
locations through Thursday. Lower amounts, broadly speaking 1 to 3
inches are possible for mainland Southwest Alaska. While these
regions are likely to be wet for much of the long term forecast
period, there is uncertainty in the exact orientation of the
atmospheric river, so many locations will likely see several
periods of moderate to heavy rain as the moisture plume wobbles
back and forth (west/east). There is some potential that the moist
southerly flow glances parts of Southcentral, with the Cook Inlet
region and southern Kenai Peninsula with the greatest potential
to see another round of lighter rainfall.

Otherwise, gusty southerly winds from a broad, weakening low
tracking into the northern Bering Sea on Sunday will lead to a low
risk of coastal flooding along the northern Kuskokwim Bay
coastline. Winds decrease on Monday as the low lifts into the
Bering Strait or across the far eastern reaches of Chukotka. High
pressure across the Gulf of Alaska keeps winds light and
conditions generally dry across Southcentral for the duration of
the forecast period (with the exception of the aforementioned
potential for glances of moisture intrusion). By Wednesday, the
next North Pacific low approaches the western Aleutians, bringing
gusty winds, potentially to gale force, and light to moderate
rainfall. The track of this low is particularly uncertain, but it
looks to be fairly slow moving and generally tracks along the
periphery of the Aleutian Chain through the end of the week.

&&

.AVIATION...

PANC...Gusty southeast winds early this morning will turn
southerly to south-southwesterly later this morning with gusts
persisting around 35 kts at times. Gusty winds will begin to
diminish this afternoon and evening with southwesterly winds
becoming around 10 kts by this evening and overnight. Southerly
winds at or less than 10 kts will persist into Saturday morning.
Rain showers will continue at times through the morning hours
with dry conditions returning around noon today to early afternoon
and persisting through Saturday morning. Regardless of the rain
showers, VFR conditions are still expected but with a 5,000 foot
cloud deck at times this morning before ceilings rise and remain
above 5,000 feet early this afternoon.

&&


$$