954
FXAK68 PAFC 201259
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
459 AM AKDT Wed Aug 20 2025

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

The location of the trough which brought rain the to region
yesterday can be seen on satellite imagery stretching from the
Copper River Basin into Prince William Sound and to the Gulf.
Behind this trough there is a ridge which has pushed far enough
east to bring some partial clearing to the western Susitna Valley.
This also brings subsidence and, in the saturated airmass, areas
of fog. The immediate forecast challenge is the potential for fog
development in the Mat-Su valleys and southward to Anchorage and
the Kenai Peninsula. With the trough stalled out and not moving,
these locations are right on the edge of clearing, which would
bring widespread fog with some locally dense fog, and enough cloud
cover to keep it from developing. Farther east, in the Copper
Basin and Prince William Sound areas, there will remain enough
lift under the trough for scattered showers to persist throughout
the day. This pattern will be sow to change through tomorrow, but
with the trough remnants continuing to weaken, there should be a
chance for a little less cloudiness Thursday and, dare we hope
for: partial clearing by Friday as an upper level ridge pokes its
way into Southcentral from the southwest.

&&


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

Currently, an upper-level ridge over the eastern Bering Sea and
Pribilof Islands continues to nudge further eastward over
Southwest Alaska. With the Pribilof Islands being under the ridge
axis, low stratus and fog are the story there this morning. So
far, Saint Paul has recorded visibility as low as 1/2 mile. Low
stratus also continues to move across the Eastern Aleutians and
the southern Alaska Peninsula this morning. Meanwhile, zonal west-
southwest to east-northeast flow occupies the western and central
Bering Sea.

Diving into the details, a trough digging into the North Pacific
from Kamchatka moves east across the western Bering Sea today and
brings rain to the southwestern and southcentral Bering as well as
the Western and Central Aleutians through Thursday morning. This
system eventually makes it to the Eastern Aleutians Thursday
afternoon and evening providing a round of rain there.

A stronger low pressure system moves northward from the North
Pacific and straddles the Kamchatka coast Thursday through Friday
as its front clips the extreme western Bering Sea through that
time period. This front will bring gusty southerly winds across
the Western Aleutians and western Bering late Thursday evening
through Friday with the peak occurring late Friday morning through
Friday afternoon. Sustained gale-force winds are likely during
this time for the Western Aleutians and western Bering. While most
precipitation associated with the front will remain to the west
of the western Aleutians, the front will drag northward a warmer
airmass across the area with fog and low stratus becoming the main
concern after the gusty winds abate Friday evening.

The pattern amplifies further Friday evening and Saturday as the
upper-level ridge currently in the North Pacific this morning will
poke up further across the Bering and southwest Alaska. As the
ridge elongates further north, the Kamchatka trough will dig
further south into the North Pacific and help to draw additional
sub-tropical moisture northward across the Western Aleutians and
western Bering Friday evening through Saturday. There is some
uncertainty regarding the overall progression of the parent low`s
front Friday evening and Saturday. The Kuskokwim Delta Coast has
the best chance for rain associated with the front for Friday
evening into Saturday morning. As of now, it looks like most
precipitation stays further to the north across the Yukon Delta
and Western Alaska. Up to this point, across the southwestern
mainland, mainly quiet weather is expected today through Saturday
with occasional showers across the higher terrain.

&&


.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...Fog development across PANC and Cook Inlet remains
possible through this morning. Turnagain Arm winds are expected
to bend towards the terminal by late this afternoon through this
evening with southerly gusts to 20 knots by 05Z. Vicinity showers
are expected to develop this afternoon and linger through this
evening.

&&


$$