241
FXAK68 PAFC 131352
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
552 AM AKDT Sun Jul 13 2025

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

A large upper-level ridge is situated over the Copper River Basin
this morning, allowing for generally clear and dry conditions
across most of the forecast area. An elongated shortwave embedded
within western periphery of the ridge axis is lifting north in
the weak southerly flow. This wave is resulting in a band of low
clouds across parts of coastal Prince William Sound and across the
Kenai Mountains north into the Susitna Valley.

It is this feature that will be the focus for shower and
thunderstorm develop again this afternoon and evening across the
Talkeetna Mountains and western and northern portions of the
Copper River Basin. The southerly flow across the Susitna Valley
could also allow for some upslope showers north of Skwentna and
Petersville, along the foothills of the Alaska Range.

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 occasional 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/TM

&&


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

Few changes to the previous forecast. Currently, isolated showers
are moving across Southwest Alaska, while fog and low stratus
blanket much of the Bering Sea. A weak low just south of the
Aleutian Chain is bringing showers to the Eastern Aleutians and
Alaska Peninsula. Further west, a front is beginning to push into
the Western Bering Sea.

For Southwest Alaska, increasing onshore flow today will bring in
cooler and more stable conditions, increasing fog and stratus
potential along the coast. While afternoon/evening thunderstorm
chances continue today, they should be limited to the Lower
Kuskokwim Valley and Western Alaska Range. A broad shortwave
trough lifts across Southwest Alaska on Monday, which will promote
widespread showers. No thunderstorms are expected due to the more
stable environment. For the beginning of the week, expect high
temperatures to cap out around 60 degrees for much of Southwest
Alaska, with slightly higher temperatures for Lower Kuskokwim
Valley and interior Bristol Bay. By late Tuesday, a low lifting up
from the North Pacific will bring steady rainfall to the Alaska
Peninsula.

For the Bering Sea and Aleutian Islands, the front moving in from
the west will be the primary weather influence for the short-term.
Expect south to southwesterly winds of 20-30 kt and steady light
to moderate rain to accompany the front. By the latter half of
Monday, a strengthening low near the Kamchatka Peninsula could
bring a period of gales to the Western Bering Sea, but there
remains some uncertainty with how strong this low will be.

&&

.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...VFR conditions will most likely persist through the
period. There is a small chance that low marine stratus may begin
to work up Cook Inlet towards the terminal this morning.
Confidence is higher for low clouds for the southern end of Cook
Inlet, but less for low clouds to work as far north as the PANC
terminal. Up-inlet, westerly flow begins by 0z this afternoon with
gusts as high as 15 kts, and relaxes Monday morning.


&&


$$