Gale Warning 473, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
447 PM AKDT Tue Aug 26 2025

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

This afternoon, satellite imagery reveals a wave of low pressure
quickly moving northward and approaching the Gulf coast. This is
out ahead of a large frontal system situated from the AKPen
northward across Bristol Bay and into the interior Southwest
zones. The coastal ridge draped mostly east of Southcentral is
gradually restrengthening as the low nears the coast, which in
turn will cause gap winds to increase. This is the first wave of
an active period of rain and wind this week for just about
everyone.

Wind for Southcentral today has been tricky as a weak gradient
set up this morning from Talkeetna to Kenai that was enough to
somewhat reorient the Turnagain Arm to keep it just south of the
Anchorage bowl. It appears this nuance is not as much of a player
anymore as there have been periods of breezy conditions across
PANC this afternoon.

Farther west, a low has developed along the frontal boundary
south of the AKPen and will gradually lift towards Bristol Bay
through tonight. Meanwhile, a shortwave trough looks to move
northeastward over Kodiak Island ahead of the main low and phase
with the Gulf system. Rainfall will likely pick up in intensity
over the Susitna Valley and Cook Inlet, along with heavier rain
for the eastern Kenai Peninsula. A period of light rain is also
possible for the Anchorage Bowl and Matanuska Valley by early
Wednesday morning.

Late Wednesday into Thursday, a more potent upper level shortwave
will lift north from the North Pacific as the upper level trough
continues to dig south over the Aleutians and AK Pen. The
shortwave will strengthen rapidly, aided by a 130kt north-south
oriented jet streak, and will also tap into a tropical moisture
feed. At the surface, a new low will spin up and drive northward
into Bristol Bay. Its front will slowly move from the western Gulf
to Prince William Sound through Thursday, and then stall over
Prince William Sound for Friday before finally exiting the region.
Multiple shortwaves will ride along the front, helping to enhance
precipitation along the coast and over most of Southcentral. Gap
winds will also continue through the week given the storm track,
with the strongest gusts likely Wednesday and Thursday afternoon
and evening. Gusts across favorable gap locations could range
between 30 and 45 mph. These gap winds will be more prevalent than
not throughout much of the week as the overall pattern stagnates,
though some lulls can be anticipated.

Rainfall totals through early Wednesday morning will be on the
order of 0.50" to 1.00" along eastern Kenai Peninsula and western
Prince William Sound and will be dependent on where the steadier
shower activity sets up as the front lifts north and a southerly
flow aloft develops. For Wednesday through Friday, rainfall totals
could top out between 2 and 4 inches, with locally higher
amounts, for many locations along the Southcentral coast. 1 to 3
inches of rain could fall across the Susitna Valley and coastal
western Kenai Peninsula. Upwards of an inch of rain is possible
for the Anchorage Bowl and Matanuska Valley, as the strong
dynamics with this system helps to negate any downsloping from the
southeasterly winds closer to mountaintop level. Around one half
to one inch of rain is also possible for the Copper River Basin on
Friday.

-AM/TM

&&

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

Active weather continues through the end of the work week. The
most impactful weather will be focused on Southwest Alaska, where
a Flood Watch is in effect for much of the region through Thursday
due to prolonged moderate to heavy rainfall. For the Bering Sea
and Aleutian Islands, gale force winds and moderate to heavy rain
are forecast from Thursday through Friday as a strong low and its
front sweep eastward across the Bering Sea. The forecast generally
remains on track, though there continues to be some uncertainty
with storm track and, thus, rain totals.

Diving into the details... radar shows a prominent band of rain
draped across Southwest Alaska as a front moves through. Rain
totals since Monday are sitting around 0.5 to 1.5 inches, though
strong winds with yesterday's rain may have led to an under-count
of rain amounts. The general synoptic picture remains on track as
this front lingers over Southwest Alaska, followed by a North
Pacific low moving in from late Wednesday through Thursday.
However, the track of this second low is much more uncertain.
There are some differences with how far west rain will extend,
with some model guidance bringing rain as far west as Bethel,
while other models keep the rain from Wednesday/Thursday's storm
from about Dillingham east. This will have implications for rain
amounts and flood potential for these areas. The speed of this low
will also factor into the timing of moderate to heavy rain, and
whether the Flood Watch may need to be extended to address
continued moderate to heavy rainfall after Thursday morning.

Less impactful but still notable will be nighttime lows dropping
into the low 40s and high 30s as cold air moves in behind the low
for Thursday night and Friday night. This influx of cold air will
lead to showers as the steadier rain tapers off on Thursday, with
the potential for more robust convection due to an unstable
vertical temperature profile. The colder air may also bring a
fresh dusting of snow to taller peaks in the Western Alaska Range,
and a momentary preview of more winter-like conditions before
temperatures warm up again with the next storm.

Speaking of the next storm, the primary feature of interest for
the Bering Sea and Aleutian Islands will be a 980-990 mb low
moving in from the west for Thursday and Friday. Confidence is
high that winds will reach gale force along its front, with
moderate rain rates. The low moves across the Western and Central
Bering/Aleutians from Thursday through Friday, reaching the
Pribilof and Eastern Aleutian Islands by Friday afternoon.

-Chen

&&

.LONG TERM FORECAST (Friday to Tuesday)...

Rainfall from this week's trough will be winding down though the
prolonged period of up inlet flow of precipitation could lead to
river rises especially in the Kenai Peninsula Rivers as well as
Yentna/Skwentna Rivers in the Susitna Valley through early next
week. A weak ridge builds into Southcentral Saturday evening into
Sunday morning though another round of rain is expected Sunday
through Tuesday.

A North Pacific low moves over Adak late this week and its front
brings strong winds and heavy rainfall to the Aleutians, the
Alaska Peninsula and Southwest Alaska. Wide spread small craft
advisories in the Bering Sea on Thursday increase to areas of gale
force winds, especially through the favored gap locations east of
Unalaska, Friday and Saturday. As the low moves toward the Bering
Strait, its front rotates through the Gulf of Alaska bringing
another round of heavy rain and gusty winds to Kodiak Island and
Southcentral Alaska for the holiday weekend.

&&

.AVIATION...

PANC...Breezy southerly winds will persist throughout the TAF
period for Anchorage, with the strongest winds expected this
evening as the coastal ridge strengthens, thus increasing the
pressure gradient. Conditions will remain VFR otherwise.

&&