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FXAK68 PAFC 311408
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
608 AM AKDT Mon Aug 31 2026

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

Key Messages:

- Frost Advisory is in effect overnight tonight from 2 AM to 9 AM
  AKDT for the Anchorage and Lower Matanuska Valley. Coldest prone
  locations (Butte, Muldoon, Campbell Tract, and the Eagle River
  Valley) could see temperatures near or below freezing. Main
  concern is for frost sensitive outdoor plants and vegetation.

- Termination dust and snow is possible for the higher elevations
  and passes. Snow levels this morning across the Alaska Range
  near Cantwell/Broad Pass, Talkeetnas, Western Chugach, and Kenai
  Mountains bottom out to roughly 2500 to 3000 feet. To the
  Central Chugach and eastern Alaska Range, near 4000 feet.

- Gusty offshore winds continue over the next few days with the
  strongest winds along the coast and through gaps and passes this
  afternoon and evening.

Discussion:

Gusty offshore winds will continue along the coast and through
gaps and passes for the next few days. Strongest winds are
expected this afternoon and evening. Precipitation associated with
an upper-level low will continue south through Southcentral
moving from northwest to southeast throughout the day. Generally,
precipitation will end by this afternoon for most locations. The
only place that could see precipitation linger is for the
Richardson Highway south of Glennallen. There is also a slight
chance (30 percent) for a brief shower early in the afternoon
across Anchorage and the Mat Valley, enhanced by orographic lift
associated as a shortwave behind the low circulation passes
through. Temperatures are expected to trend cooler as an arctic
airmass moves through and skies clear across the region.

With colder air moving in aloft, lapse rates are becoming more
unstable. Lower elevations will see primarily rain though. Several
lightning strikes were observed however with showers near Cordova
and east this morning. Strong showers moving across the MatSu and
Anchorage produced a couple lightning strikes near Big Lake and
the vicinity of Anchorage. At higher elevations, snow is possible
at higher elevations this morning with termination dust on the
mountain peaks and through Broad, Tahneta, Isabel, and Hatcher
Passes. Snow levels this morning across the Alaska Range near
Cantwell/Broad Pass, Talkeetnas, Western Chugach, and Kenai
Mountains bottom out to roughly 2500 to 3000 feet. To the Central
Chugach and eastern Alaska Range, near 4000 feet. Road
temperatures will be warm enough to limit accumulation.

Temperatures will cool considerably behind this low. Clearing
skies and a cold airmass will allow temperatures to fall sharply
tonight into Tuesday morning. A Frost Advisory is in effect from 2
AM to 9 AM AKDT Tuesday for Anchorage and the Lower Matanuska
Valley. Temperatures could fall as low as the upper 20s in
typically colder locations, with frost capable of occurring. Other
portions of Southcentral, including the lower Susitna Valley and
western Kenai Peninsula, will also have the potential for near-
freezing temperatures and patchy frost Tuesday morning. Wednesday
morning will remain chilly, though frost potential currently looks
less widespread as temperatures begin to moderate.

Tuesday into Wednesday, broad northwesterly flow remains over
Southcentral as the main upper low shifts southeast. Additional
weak shortwaves embedded within the flow may produce periods of
increases cloud cover and isolated to scattered showers,
particularly over the higher terrain and Copper River Basin. By
Wednesday, model guidance show heights beginning to rise as an
upper-level ridge builds eastward toward Southcentral, allowing
for a gradual moderating and drying trend.

LM/Rux

&&


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

The active pattern in the Bering continues as a front remains
stalled from from the Shemya area, the Pribilof Islands and the
Alaska Peninsula. Weak lows are moving along the front, which is
bringing widespread rainfall and gusty winds to those regions.
Meanwhile in the Southwest Mainland, a cold and dry airmass will
persist through Wednesday, allowing for low temperatures to drop
into the 30s across interior Southwest Alaska. Coastal regions
will see low temperatures in the low to mid 40s.

Across the Bering, the strong ridge remains anchored in the North
Pacific with a series of shortwaves rounding the top of the
ridge. These various systems will take similar tracks, bringing
periods of gusty winds and rainfall to the western Aleutians, the
Pribilof Islands, and the Alaska Peninsula through Tuesday. Across
the southern Bering and Aleutian Chain, including those areas
under the ridge from Adak to Unalaska, high-end small-craft winds
and gale-force gusts persist through the first half of the week.
Fog and low stratus will be possible over the area of ridging and
in-between shortwaves elsewhere.

On Tuesday, a low moves into the Western Aleutians, bringing gale
force winds and rainfall. This low will push the ridge eastward,
but the ridge strengthens as it moves, becoming taller and
diminishing rain chances in the Pribilof Islands and the Alaska
Peninsula on Wednesday. The low seems to remain nearly stationary
in the Shemya region, perhaps finally moving east by Thursday.
Its front looks to push east across the Bering Tuesday morning
through Wednesday, arriving at the Pribilof Islands and Unalaska
by Wednesday afternoon. The front will advect a warm, tropical
airmass into the region as it progresses, leading to warmer
temperatures over the Aleutians. A robust stream of Pacific
moisture brings potentially moderate to heavy rain while strong
southerly winds advance east across the Aleutian Chain Tuesday
through Wednesday. Stay tuned for updates as this system evolves
and reaches the Southwest Alaska coast by the latter half of this
week.

-JAR/JH

&&


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

The long-term period looks to remain active, especially across
Southwest Alaska, The Bering Sea, and the Aleutian Chain. Thursday
features a strong upper-level low in the western Bering with a
ridge moving into the western Gulf of Alaska. A strong shortwave
will move north along a stalled frontal boundary which will lead
to the development of a surface low between Saint Matthew Island
and Saint Lawrence Island late Thursday morning into Thursday
afternoon. This low and its front will aid in another round of
heavy rain for the and gusty southwesterly winds along the coast
for Thursday.

Across Southcentral Alaska, the ridge will be overhead for much
of Thursday with relatively quiet weather anticipated. The ridge
moves east to the eastern Gulf of Alaska and into Yukon, Canada
for Friday which will open the door to southwest flow aloft.
Steady rain from Southwest will move into Southcentral through
Friday as a plethora of shortwaves lift up and over the area from
North Pacific and Gulf. Showers continue over Southwest, the
Aleutian Chain, and Southcentral for Saturday as a broad upper-
level trough remains in the Bering and southwest flow aloft
remains across Southcentral.

Guidance diverges for Saturday evening and into Sunday and
forecast confidence begins to wane. The point of disagreement
comes with how guidance handles the strength and track of a
shortwave rounding the base of the broad Bering trough as well as
the placement of the upper- level ridge to the east. The GFS and
Canadian guidance have the ridge farther to the southeast with its
axis mostly over British Columbia while the European guidance has
the ridge axis more to the west with its axis over Southeast
Alaska. The GFS also closes the shortwave off into an upper-level
over the Gulf the Canadian and European guidance depicts more of
an open wave(s). Regardless, Saturday night through Sunday looks
wet across the Southern Mainland, its a matter of pinpointing who
receives higher magnitudes of rain and who sees just showers. As
timing gets closer, details should become more clearer on these
points of disagreement.

&&


.AVIATION...

PANC...Rainfall may lower ceilings to MVFR conditions this
morning. A few lightning strikes have been observed this morning
in the vicinity and the threat for isolated thunderstorms will
last until 16Z. Generally expect a drying trend with clearing
skies throughout the day. However, there is a small chance (30
percent) that a brief shower may occur early this afternoon, but
all precipitation should be out of the area by 00Z. Gusty
northerly winds are expected to increase throughout the day.

&&


$$