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FXAK68 PAFC 060054
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
454 PM AKDT Sat Jul 5 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Monday night)...

Upper level ridging over interior Alaska has once again helped to
clear out morning cloud cover over the Copper River Basin. Cloud
cover has been more persistent over the Talkeetnas and northern
Susitna Valley and has subsequently kept temperatures slightly
cooler. Regardless of the clouds, daytime temperatures have warmed
into the upper 60s and lower 70s across much of the region.
Prince William Sound and coastal areas continue to be the cool
locales with temperatures in the 50s. For the rest of this
afternoon, strong daytime heating and the passage of another
shortwave trough will contribute to destabilization of the
atmosphere over northern portions of Southcentral. Isolated to
widely scattered wet thunderstorms and convective showers are
anticipated over the Susitna Valley and Copper Basin through the
evening hours.

Meanwhile, coastal ridging downstream of an approaching front and
warmer interior temperatures will see a tightened pressure
gradient with increasing gap winds through Southcentral for the
rest of today. The Copper River wind and Knik River wind could see
gusts as high as 35 mph this afternoon and evening while gusts
through the Turnagain Arm could gust anywhere from 30 to 40 mph.

The driest location across Southcentral is near the Tok Cutoff,
where temperatures are already in the mid to upper 70s with RH
values near or just below 30 percent. Increasing winds gusting to
15 to 20 mph may briefly result in Hot-Dry-Windy conditions later
this evening, but RH values at or above 25 percent will quickly
rebound with the loss of daytime heating. As mentioned in the
previous discussion, showers will likely keep going through the
overnight hours for the Talkeetna Mountains and northern Susitna
Valley with the slow departure of the shortwave trough tonight.
Further south, a trough over the western Gulf will struggle to
lift northward toward Southcentral, keeping rain confined to
Kodiak Island and the Gulf for the remainder of today.

Sunday will be a transition day as the ridge weakens to the north
and the upper low shifts into the Gulf, with short-waves rotating
northward toward Southcentral. Increased cloud cover will lead to
somewhat more stable conditions inland, with much less convection
expected. Steady rain will settle in along the north Gulf coast
and Prince William Sound. Short-waves will then rotate northward
into Southcentral Sunday night through Monday, though model
guidance varies on the exact track of short-waves. Rain is likely
ahead of the short-waves, especially from Prince William Sound to
the Copper River Basin. The big question is how far west rain will
make it, as the upper low in the Gulf will continue eastward
toward Southeast Alaska, causing flow over Southcentral to shift
toward northerly and change the direction of flow (and movement of
short-waves). Stay tuned, as there is potential for widespread
wetting rains to start the work week.

Forecast confidence continues to fall Monday night into Tuesday
as an Arctic trough digs southward across mainland Alaska. Model
guidance continues to struggle with the ultimate track and
amplitude of the Arctic trough, with individual short-waves
leading to wildly different solutions among the guidance. The
likely bet is that unsettled weather will persist as we continue
through the work week.

-SEB/BL

&&


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

Currently, there is a large low over the east Aleutians/Alaska
Peninsula region. This is bringing rainfall and gusty winds to
Bristol Bay and the Alaska Peninsula. Attention shifts the
Kuskokwim Delta and the Lower Kuskokwim Valley over the evening as
a wave passes through and kicks off chances for thunderstorms. The
Lower Kuskokwim Valley will have the best chances for
thunderstorms with this wave. In the Kuskokwim Valley,
thunderstorms will be most likely north of Aniak and Bethel.
The Bethel and Aniak communities will likely stay in a stratiform
rainfall region. There is uncertainty in exactly where and if the
thunderstorms will form with some models bringing them further
south or north. Rain chances will continue in the aforementioned
regions though Sunday evening. The Southwest Mainland dries out
on Monday as slack flow builds in. Winds become light and
precipitation chances diminish, lasting through Wednesday.
However, chances for thunderstorms remain in the Lower Kuskokwim
Delta, particularly closer to the Alaska Range.

The Bering will be fairly active. A front from a low in the North
Pacific will enter the western Aleutians on Sunday. Rainfall and
gusty winds will accompany the low as it tracks eastward. The low
will strengthen as it moves east, eventually reaching the eastern
Aleutians by Wednesday. Another bout of rainfall and gusty winds
will impact the Eastern Aleutians and Alaska Peninsula region
once the low arrives. There is decent model agreement on this
scenario, so confidence is increased.

-JAR

&&

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

The long-term period begins with a shortwave ridge over
Southcentral Alaska, weak flow across Southwest Alaska, and a
North Pacific low south of the Eastern Aleutians and southern
Alaska Peninsula (AKPEN). The ridge over Southcentral Wednesday
looks to move northward and reorient with a more east to west axis
across the central interior by Thursday. This will open the door
for the North Pacific low to move into the Gulf of Alaska by
Thursday. Wettest locations look to be across Kodiak Island, the
Eastern Kenai Peninsula, and Prince William Sound with scattered
showers for Southwest and interior Southcentral. Steady rains
across the Southcentral coast taper off to a more showery regime
Friday and Saturday very much like inland locations as the low
weakens and energy goes to Southeast Alaska.

Further to the west, an upper level shortwave looks to dig
southward from northern Kamchatka into the central Bering by
Thursday. Rain looks to be mostly confined to the Bering but may
make it as far south as the Pribilof Islands and as far east as
Nunivak Island. Elsewhere, a ridge across the western Bering will
weaken into Thursday and allow for a few weak systems tracking
southeastward from southern Kamchatka to move over the Western
Aleutians and Bering by Friday. Rain with these systems will be
light. The ridge looks to build back across the western Bering by
Saturday. Confidence remains low and uncertainty remains high
regarding the track of a North Pacific low Thursday through
Saturday. Some guidance keeps the low south of the Aleutian Chain
(Canadian and somewhat the ECMWF) while some guidance wants to
clip the Central/Eastern Aleutians and southern AKPEN with the
front bringing another round of light rain to those areas.

&&.AVIATION...

PANC...VFR conditions will persist. There is high confidence in
strong gusty southeasterly winds developing later this afternoon
through the Turnagain Arm and bending into the terminal at
times. Gusts of 30 to 35 kts are possible through about 09-10Z
Sunday then are expected to quickly shut off as winds turn down
inlet. Isolated to scattered showers are possible through the
period along the Chugach Mountains and possibly working into the
vicinity of the terminal.

&&


$$