626
FXAK68 PAFC 050034
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
434 PM AKDT Thu Sep 4 2025

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

Synoptically, an upper ridge over the AlCan border begins to
erode overnight as a trough currently stretching from the Susitna
Valley to the southern Kenai Peninsula moves eastward.

Scattered rain showers for the Kenai Peninsula northward through
the Wasilla / Palmer area and into the Susitna Valley will
persist this evening as a trough moves slowly across the region.
The rainfall amounts will be highest in the Susitna Valley and
also in upsloping, mountainous areas. A flood advisory remains in
effect for this area through 10:00 am Friday morning. This trough
moves eastward overnight continuing the rain showers for most of
these areas through late Friday morning. In its wake, dry
conditions and cooler northwest air flows into the area. Another
chance of rain returns for Saturday as a storm currently
approaching Southwest Alaska moves eastward.

Temperatures in the Copper River Basin today reached the lower 70s
as a ridge of high pressure dominated. Overnight, the
aforementioned trough will bring an end to these conditions as
clouds and scattered rain showers arrive. This trough quickly
dissipates Friday afternoon allowing for dry and cooler conditions
the remainder of Friday. Winds through the Prince William Sound
gaps will remain breezy into Friday evening though diminish for
Saturday.

-Johnston

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA / BERING SEA / ALEUTIANS
(Today through Sunday)...

Currently, there is a ridge in place in the Eastern Aleutians.
This is allowing for areas of clear skies, lower chances for rain,
and light winds around that area. The mainland is seeing rain
showers slowly taper off as the ridge moves eastward. Showers
should end by the morning hours of Friday in the mainland. The
main story for today into the weekend is the large low that is
currently over the Western Aleutians. The low is already bringing
gale force winds to Shemya and Adak. The triple point low at the
surface is forming clusters of marine thunderstorms between from
just west of Kiska to west of Adak. These marine thunderstorms
will taper off as colder air wraps around the low by Friday
morning. Moderate to heavy rain is also being seen in the
aforementioned locations.

The low will progress to the Eastern Aleutians/Alaska Peninsula
region by Friday morning. Gusty gale force winds are expected
first for the Pribilof Islands and the Fox Islands by Friday
morning. Then, by Friday afternoon, the Alaska Peninsula and the
Southwest coast will see high end small craft winds. Again,
moderate to heavy rainfall will also accompany the low in these
areas. The back end of the low will drive another round of gale
force winds in the Western Aleutians at this point. Saturday has
southerly small craft winds affecting communities along the
Kuskokwim Delta coast. This will cause water levels to rise above
high tide, but significant coastal flooding is not expected at
this time. It is something to keep monitoring, so check back for
updates. The low quickly weakens after this point with some
lingering northwesterly small craft winds from the Pribilof
Islands to Unalaska on Sunday morning. Ridging builds into the
Bering on Sunday, which allows for calm winds and lower chances
for rainfall. Another low looms on the horizon. This north Pacific
low rises into the Adak region Sunday night. There is uncertainty
on its track, but this low may be stronger the the current one.

-JAR

&&

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

At the beginning of next week, a gale or potentially storm-force
low is likely to be located near the central Aleutians. To the
east, a trough extends south across Western Alaska into the Gulf
of Alaska. Near and ahead of the trough axis, rain showers will be
favored as a former surface low pressure system winds down and
deposits its moisture across the state. The trough exits east into
Yukon by Tuesday, with a quickly-progressing ridge moving in to
replace it across southern mainland Alaska. As a result, rain
showers diminish across the region. Along the Aleutians, it is
difficult to pinpoint impacts from the potentially storm-force
low, as there is significant uncertainty in the track. Regardless,
expect periods of strong, gusty winds, potentially as strong as
storm force. Accompanying the low will also be tropical moisture
with precipitable water values of 1.5 inches or greater sourced
from Tropical Storm Peipah (currently located over southwestern
Japan) and strong dynamics which will lead to moderate to heavy
rain along the Aleutians on Monday.

For Tuesday, the low tracks near or along the Aleutians toward the
Alaska Peninsula or into the southeastern Bering Sea. The
occluding low begins to lose some of its moisture tap and
strength, though its front, depending on track, may lift into the
Southwest Alaska coast near gale force. This would lead to a low
potential for some coastal flooding/erosion concerns on Tuesday,
though a more southern track would negate this potential. Light
to moderate rainfall begins to move inland over parts of Southwest
Alaska, regardless of track. In general, the low appears stronger
than the previous low, so winds and precipitation are expected to
be greater than what is seen on Friday and Saturday.

The low tracks somewhere in the vicinity of Bristol Bay to Kodiak
Island by Wednesday. Its front pushes east along the Gulf of
Alaska coast, where it may cause moderate to heavy rain along the
coastal mountains. The abundant moisture and weak to moderate
cross-barrier flow likely allows for at least some rainfall to
push past the coastal mountains into inland Southcentral at times.
The low continues to shift slowly eastward toward the end of the
week, keeping generally showery conditions in place across the
southern mainland, with heavier rain along the coast. For the
Bering Sea and Aleutians, surface high pressure moves in mid-week,
though the upper-level pattern appears fairly messy and the
confidence in any individual feature`s location is very low.

Quesada

&&

.AVIATION...

PANC...Rain will move into Anchorage late afternoon into the
evening today as a trough slowly shifts east. Ceilings will
generally deteriorate from VFR to MVFR and potentially even IFR
overnight. Conditions improve by late tomorrow morning in wake of
the system. Southerly winds will generally prevail through the
period.

&&
$$