601
FXAK68 PAFC 211250
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
450 AM AKDT Thu Aug 21 2025

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

Low level convergence of southerly winds moving up Cook Inlet with
southeasterly Turnagain Arm winds was enough to initiate some
persistent showers over Anchorage and parts of the Mat-Su valleys
for much of the night. With the Turnagain Arm winds diminishing
toward morning, these showers stopped developing. A weak upper
level wave moving across Southcentral will keep skies mostly
cloudy over the region today. This shortwave will stall out and
dissipate tomorrow which will allow some periods of sunshine as
we head into the weekend. This may not be long lasting as a front
will move from Southwest Alaska into Southcentral late Saturday
which could bring in some rain, especially for the Susitna Valley.


&&


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

An upper-level ridge over mainland Southwest Alaska this morning
will begin to weaken through the morning as a weak upper-level
trough comes ashore from the eastern Bering Sea. There will not be
a lot of precipitation associated with this feature and the
majority of showery activity it does produce will remain along the
higher terrain of the mountain ranges. West to east zonal flow
remains in the upper levels across the central and western Bering
Sea and Aleutian Chain. An embedded shortwave in the flow will
spread rain across the Aleutian Chain today before upper-level
ridging moves in for Friday. There have been a few lightning
strikes across the Western Aleutians and western Bering since last
night. With continued instability aloft, lightning strikes are
possible again today mostly on the Bering Sea side coastal marine
zones north of the Central and Western Aleutians.

Quiet weather remains across mainland Southwest Alaska Friday
through most of Saturday as upper-level remains weak. Therefore,
low stratus and fog will be possible across the southwestern
mainland, especially for Friday. Back to the west, a North Pacific
low moves to along the Kamchatka coast and sends its front into
the far western Bering Sea this morning as the low continues along
the Kamchatka coast through Friday evening. The far western
Aleutians could be clipped with some rain by the southern end of
the front this morning. The bigger story will be the gale-force
winds associated with the low and front today through Friday along
the western Bering. This low looks to move to the Gulf of Anadyr
by Friday evening with the front moving inland of Western Alaska.
While most precipitation associated with the front will remain to
the north of Southwest Alaska, the best chance (50%)for some light
rain is mainly along the Kuskokwim Delta Coast and Nunivak Island
Friday night and Saturday morning with lower chances (30%)
elsewhere across the southwestern mainland. Showers look to
persist through Saturday across the southwest mainland but mainly
confined to the higher terrain.

The upper-level ridge that will have moved across the central and
eastern Bering Friday morning will begin to amplify further as it
extends further north and east to encompass the eastern Bering
and portions of the Southwest Alaska by Friday afternoon and
evening. In response, the trough across Kamchatka, responsible for
guiding the gale-force low along the Kamchatka coast, will also
amplify further by digging southward. This will allow sub-tropical
moisture to surge northward to the Western Aleutians by Friday
afternoon. A corridor of moderate to heavy rain will remain across
the Western Aleutians Friday through Sunday as it slowly tracks
eastward with time. This moderate to heavy precipitation looks to
reach Central Aleutians and Pribilof Islands by Sunday afternoon.
There are indications that this band of precipitation could also
move into the northern portions of the Kuskokwim Delta Coast and
Nunivak Island also by Sunday afternoon. Stay tuned as we begin to
dig into the finer details of the upcoming wetter pattern shaping
up for the weekend and into next week.

&&


.LONG TERM FORECAST (Saturday through Wednesday)...

High pressure continues to flatten through this weekend as it
stretches across Bristol Bay and into Southcentral. A low over
continues to linger over the North Pacific, influencing the Gulf
of Alaska. Frontal passages span the Bering Sea as a low skims the
coast of Russia.

As the low center near Russia deepens and begins to track
eastward, chances appear more likely for the high pressure ridge
to breakdown and retreat southward early next week. Deep southwest
flow with an amble moisture fetch would direct its energy over
the Aleutians and across the Bering Sea Monday. By Tuesday, models
point toward not only a soggy weather pattern with moderate to
heavy rainfall at times, but also gusty southwesterly winds that
would raise the potential for coastal flooding along the Southwest
coast.

Model agreement decreases by midweek, but the general idea is
that the Northern Pacific low will follow a track along with the
ridge by moving southward and the low near the Russian coast will
have moved east toward the Northern Bering. A surface low
deepening south of the Aleutians will help fuel the amplified
pattern, but there are some differences in how the orientation of
the trough progresses through midweek. The differences in outcomes
could mean different forecasts with timing, duration, and amounts
of precipitation any given location would get, as it tracks along
the Alaska Peninsula and Kodiak Island. This also affects how far
east the weather system progresses toward Southcentral and its
subsequential precipitation.


&&

.AVIATION...

PANC...The likelihood of showers in the vicinity and MVFR
ceilings continues to decrease throughout this morning. Southerly
winds up to 10 knots and VFR conditions are expected to prevail
through this afternoon and evening.

&&


$$