506
FXAK68 PAFC 130103
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
503 PM AKDT Sat Jul 12 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
3/Today through Tuesday evening)...

Currently, there is a large upper high over Central Alaska. This
high is allowing for calm winds and clearer conditions across
Southcentral. However, there are some weak shortwaves moving
through the region. Showers and thunderstorms are possible in the
Talkeetna Mountains and the higher elevations of the Copper River
Basin with these waves. The Susitna Valley could see some storms
moves in from the Talkeetna Mountains due to easterly storm
motion. Sunday is almost the same story as today (Saturday). The
high will slowly track eastward, but will still influence the
region in the form of light winds and lower rain chances. There
will still be instability present in the Talkeetna Mountains and
the Copper River Basin, so chances for showers and thunderstorms
remain.

A pattern shift occurs on Monday. The upper high moves east into
Canada while a more troughy pattern moves into Southcentral. A
front pushes in from the south, allowing for widespread light
rainfall across the interior of Southcentral. Some blocking will
occur in the Susitna Valley, but the Anchorage, and Matanuska
Valley should see rainfall lasting through Tuesday morning. As
with everything, there is uncertainty in how this situation will
unfold. Some guidance has the front taking a more eastward track,
leaving the Anchorage and Mat-Su Valley regions drier and giving
the Prince William Sound region the brunt of the rainfall. Other
guidance has the core of rainfall impacting Anchorage and Palmer.
The real solution will likely fall somewhere in the middle. Winds
will pick up to an extent in the gap regions, but will remain on
the weaker side with this shortwave. Temperatures will cool down
to the upper 50s and low 60s thanks to the increased cloud cover
and rainfall. Afterwards, weaker shortwaves will pass through from
the west, keeping rain chances elevated in the higher elevations.

Looking ahead to Wednesday shows that model agreement falls off
the cliff as a low in the north Pacific tracks eastward. Most
guidance has a different scenario with some tracking it into the
Gulf of Alaska while others have it take a more northerly track.
The only thing that can be deciphered is that some kind of a front
will move into Southcentral.

-JAR


&&


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

Southwest Alaska and the Bering Sea remain fairly quiet under a
weak flow regime. Weak ridging over the Alaska mainland continues
to build in today over Southwest Alaska, leading to high
temperatures in 70s for most of interior Southwest Alaska. Weak
shortwaves rotating around the ridge have combined with these warm
temperatures to produce scattered to numerous showers along an
axis from the Western Alaska Range over the Kilbuck and Ahklun
Mountains. Though none of have been observed yet, embedded within
these showers is the potential for some isolated thunderstorms
this evening. Showers are forecast to move off the high terrain
into the Kuskokwim Delta, bringing thunderstorm potential with
them. Showers, and any thunderstorms along with them, diminish
tonight with the loss of surface heating.

Out west, a weak surface low brings light rain and low stratus to
the Bering Sea and Aleutians. The low dips south of the Aleutian
Chain tonight, spreading precipitation as far as the eastern
Aleutians and southern Alaska Peninsula. Otherwise, a col over the
eastern Bering Sea leads to stagnant conditions with stratus and
fog. The upper component of the low weakens and elongates, pushing
back north on Sunday. This combines with an incoming front off a
Kamchatka low that returns southerly winds to the western Bering
Sea.

Light offshore flow for Southwest Alaska shifts onshore and
intensifies as surface high pressure builds to the east over the
Gulf of Alaska beginning tonight. This will bring in cooler and
more stable conditions, increasing fog and stratus potential along
the coast. Additionally, thunderstorms retreat inland for Sunday
afternoon/evening, being limited to the Lower Kuskokwim Valley
and Western Alaska Range.

By Monday, the bulk of the front pushing into the Bering reaches
the Pribilof Islands, though winds remain below gale force. A
broad shortwave trough lifts across Southwest Alaska, which will
continue to promote showers each afternoon and evening. For the
beginning of the week, expect high temperatures to cap out around
60 degrees for much of Southwest Alaska. On Tuesday, in addition
to the low out west, a second low lifts up around the ridge in the
Gulf/Northeast Pacific, bringing steady rainfall to the Alaska
Peninsula.


&&


.LONG TERM FORECAST (Days 4 through 7: Wednesday through
Saturday)...

The longterm forecast begins on Wednesday with a low in the
northwestern Gulf of Alaska and another low in the western Bering
Sea. Models are still struggling with the placement and evolution
of the low in the Gulf of Alaska. The GFS quickly moves the low
to the northeast into Canada by Thursday morning, the Canadian
shows the low tracking to the northwest and being absorbed into
the aforementioned Bering low, and the ECMWF has the Gulf low
moving due east to the Alaska Panhandle by Friday morning.
Therefore, confidence on precipitation and sky conditions is
still low. Towards the end of the longterm, high pressure builds
across the Copper River Basin and should promote a better chance
for less clouds and drier conditions.

In the Bering Sea, the low pressure system generally remains over
the Bering during most of the longterm while high pressure
strengthens over the AK Mainland. The main uncertainty with the
Bering low is in regards to how it interacts with surrounding
shortwaves/lows and the speed of its surface front. The GFS
solution would push the front quickly across SW AK and portions of
Southcentral (with the bulk of precipitation across SW on Saturday
morning), whereas the Canadian front is slower (with the bulk of
precipitation across SW on Sunday morning). Nonetheless, expect an
active pattern out west during the long term period.


&&


.AVIATION...

PANC...Ceilings expected to remain primarily VFR between 5-8 kft through
this evening with the potential for scattered showers mainly along
the Chugach Mountains. High pressure will build into the region
tonight with winds remaining light. This could set the stage for
low marine stratus to begin to work up the Cook Inlet towards the
terminal by Sunday morning. Confidence is stronger for low clouds
for the southern end of Cook Inlet, but less so for the low
clouds to work as far north as the PANC terminal Sunday morning.


&&


$$