Area Forecast Discussion
Issued by NWS Anchorage, AK

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685
FXAK68 PAFC 200109
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
509 PM AKDT Tue Aug 19 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: This
afternoon through Friday afternoon)...

Widespread rain continues across the Southcentral Mainland today
as an Arctic trough digs across the region. Then, warmer and drier
with isolated showers through Friday afternoon behind the trough.
Winds pick up as a coastal ridge of high pressure develops,
leading to gusty southeasterly winds through gaps and passes.
Overall forecast confidence is low to medium, with uncertainty
regarding: (1) rain amounts with today`s system, (2) fog potential
tomorrow morning, and (3) where showers will develop later this
week. However, weather impacts will also likely remain low, as no
hazardous conditions are currently anticipated.

Diving into the details... rain amounts with the Arctic trough
remain uncertain as models continue to show inconsistencies from
run to run. Generally, the latest model guidance has trended
towards the trough diving further south and remaining further
west. As such, rain amounts have increased along the Talkeetna,
Chugach, and Kenai Mountains, with reduced rain amounts for the
Copper River Basin. Confidence is lowest for Mat-Su Valleys,
Anchorage, and Western Kenai Peninsula, which will be on the
periphery of the rain band associated with this trough. Radar, as
of the writing of this discussion at 4pm, also has been slow to
fill in, suggesting that overall rain amounts may lean lower than
what`s currently in the forecast.

As rain begins to taper off tonight into tomorrow morning, there
is the potential for fog from Anchorage north into the Mat-Su as
higher pressure builds in and traps low-level moisture from the
recent rainfall. Confidence is low regarding fog potential,
especially if less rain falls than initially forecast. Overall, be
alert to the potential for fog to affect your commute or outdoor
activities tomorrow morning.

After the passage of today`s trough, generally expect warmer
conditions, with a trend towards drier weather through the end of
the work week. Weak upper level shortwaves will keep a chance for
showers in the forecast, especially along higher elevation. In
addition, this will keep skies partly to mostly cloudy.

-Chen

&&


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

This afternoon, the main weather feature is a 500 mb arctic
trough digging across the mainland. Though most of its energy is
concentrated to the east, some areas of showers are clipping the
eastern most zones of the lower Kuskokwim Valley. The combination
of upper level negative (or anti-cyclonic) vorticity advection and
transient surface high pressure moving into Southwest this
evening will result in subsidence and clearing skies for the
overnight hours. This will allow for tonight`s low temperatures
across Southwest to dip down into the upper 30s and lower 40s.

At the same time, a front moving over the west-central Bering Sea
falls apart with only a few showers possible this evening for
Amchitka and Adak. In the wake of the front, high pressure and
warm air advection will likely promote low stratus and areas of
fog. The current fog forecast for the Bering Sea has been scaled
back a bit from this morning. Model guidance of favorable fog
parameters suggest that most of the fog will be confined to the
southern Bering Sea and Nikolski westward to Shemya. Otherwise,
the next features to watch for will be a weak low lifting out of
the North Pacific and tracking along the Aleutian Chain Wednesday
evening through Thursday. This system looks to be non-impactful
and dissipates by Thursday evening. On the heels of the
aforementioned disturbance, a stronger low moves into the Western
Bering by late Thursday. Models differ on precipitation coverage,
but most of the guidance brings small craft winds into the Western
Aleutians by Friday morning.

-AM/JH

&&


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

For the Bering Sea, the Aleutians and Southwest Alaska: Confidence
in the ridge of high pressure breaking down this weekend and
retreating southward into the North Pacific remains moderate.
Simultaneously, a strong low moves toward the Bering Strait
causing rounds of precipitation to flow over the northern side of
the high. As the high flattens and moves southward, signals
continue to point toward an atmospheric river influence early
next week. This would result in more widespread precipitation in
the Aleutians and the Southwest Mainland.

For Southcentral: An upper-level low moves through the Interior
this weekend. This brings mostly cloudy skies and the chance of rain
to the region through early next week.

&&.AVIATION...

PANC...Showers are expected to expand across Anchorage, including
PANC, through this afternoon into early evening as a trough pushes
through. Fog may develop overnight across PANC and Cook Inlet, but
high uncertainty exists due to the uncertainty with today`s
rainfall and overnight cloud cover. Otherwise, light and variable
winds will prevail before becoming southerly tonight.

&&


$$