849
FXAK68 PAFC 030045
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
445 PM AKDT Sun Jun 2 2024

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

An occluded low south of Kodiak Island this afternoon will weaken
overnight. Its occluded front will remain draped over the
northern gulf, producing steady rain and easterly winds up to 30
kt across the northern Gulf, weakening by Monday morning. For
Kodiak City, an additional 0.6" of rain could fall by Monday
afternoon with up to 2" for the northern mountains of Kodiak
Island.

Shower activity across interior Southcentral will be less
pronounced overnight due to weak upper-level ridging ahead of the
upper-level shortwave over the northern Gulf yields breaks in the
cloud cover along with slightly warmer temperatures Monday.

By Monday afternoon, another upper-level shortwave rotating
around the nearly stationary upper-level low over the Gulf will
help to push the occluded front into the Southcentral coast as the
shortwave itself moves inland. The result will be a more
southeasterly flow aloft that will usher in clouds and moisture in
the form of scattered showers. Most of the shower activity will
be across the Copper River Basin and along both the coastal
mountains and Alaska Range. A few isolated showers will also be
possible west of the Chugach and Kenai mountains for the first
half of Monday.

Another easterly upper-level shortwave passes over interior
Southcentral early Wednesday with widespread shower activity from
the Copper River Basin to the Mat-Su Valleys. However, there is
still some uncertainty as to the strength and timing of
precipitation.

&&

SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE
ALEUTIANS (Days 1 through 3)...

A broad trough just south of the Alaska Peninsula digs into the
Gulf of Alaska Monday as a high pressure ridge builds in over the
Bering. This alignment of systems will continue to help produce
easterly waves over Southwest tonight through Monday night. A
long band of rain showers is currently located over the Middle
Kuskokwim Valley and Bristol Bay, and will continue to move
southwest towards the eastern Aleutians into tomorrow morning. To
the north of this band of rain near Aniak, an isolated line of
thunderstorms is also moving to the southwest towards Bethel and
should diminish before midnight. This continued pattern into
Tuesday will allow the potential for isolated thunderstorms to
take place near the western Alaska Range and Middle Kuskokwim
Valley tomorrow afternoon and evening.

As high pressure builds in over the Bering on Monday, an Arctic
low is developing in northern Alaska and will dig southwards
towards the eastern Bering through the forecast period. Ahead of
it, a surge of cold air will push the high pressure ridge south of
the Aleutians Monday evening. This cold air mass will help force
northerly small craft force winds over much of the central and
eastern Bering, while locations near Nunivak Island and south of
the eastern Aleutians will experience gale force winds Monday
night and Tuesday. Precipitation impacts over the Bering will be
limited since the low will be surrounded by drier air until it
moves further south.

The Arctic low will continue to move southward and eventually
enter the eastern Bering by Wednesday afternoon. As it does so,
the placement of it and the upper trough in the Gulf of Alaska
will create a convergence band of rain over the Kuskokwim Delta
and Bristol Bay Monday night through Tuesday morning. Conditions
will be quieter Tuesday and Wednesday, with more scattered showers
across southwest and slightly cooler temperature as the Arctic low
digs south. Looking ahead, a broad easterly shortwave producing
widespread precipitation will begin to move across southern
Alaska Wednesday and reach the western Alaska Range by the
evening hours.

-BS

&&

.LONG TERM FORECAST (Days 4 through 7) Thursday through Sunday...

A generally unsettled pattern remains for much of southern Alaska
for the beginning of the period as a large upper low sits over
the Bering. This feature looks to wobble around and slowly dive
southward through the end of the week. Moderate precipitation
continues across much of Southcentral on Thursday, heaviest along
the coast, gradually ending through Friday.

Models are in good agreement on the upper level pattern
amplifying as a shortwave and associated surface low swinging
around the base of the Bering upper low strengthens while moving
into the Gulf for the weekend. There are still differences in the
timing of this system, and consequently also the strength of the
ridge over Southcentral ahead of this system on Saturday, with the
GFS/GEFS being the strongest and most amplified solution.
Regardless, areas of moderate to locally heavy precipitation are
likely, especially along portions of the coast of Southcentral and
Alaska Peninsula this weekend. Scattered rain showers look to
remain across most of the Aleutians throughout the entire period.

-ME

&&
.AVIATION...

PANC...Gusty southeasterly winds out the Turnagain Arm will
continue this afternoon and into the evening before abating some
overnight. Gusty southeast Turnagain Arm winds can be expected
again Monday afternoon/evening. Otherwise, expect VFR conditions
to prevail throughout the rest of the TAF period.

&&


$$