596
FXAK68 PAFC 090116
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
516 PM AKDT Sat Jun 8 2024

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

A broad longwave trough over the southern Gulf of Alaska will
start to send multiple fronts over Southcentral starting tonight.
The first front has been over the central Gulf, sending a line of
very moist air over Kodiak Island throughout the day today and
will continue to do so through the remainder of the weekend. The
Flood Watch for the island is still in effect through late Sunday
night for an additional 2-3 inches of rain still possible. A brief
lull overnight will subside to another front passing over on
Sunday, providing an additional round of heavier precipitation.

As the current front over the Gulf moves over Southcentral
tonight, gap winds near Turnagain Arm, Knik River Valley, and the
Copper River Valley will quickly increase and persist through the
overnight hours. A Special Weather Statement is out for the
potential of gusty winds briefly bending into Anchorage this
evening. The duration of this will be short lived as the energy
of the frontal passage will be the main factor in turning the
Turnagain Arm wind northward. Relatively cooler temperatures will
move in over the region and last through at least Tuesday
afternoon. Additionally, the multiple fronts moving northward from
the trough in the Gulf will increase the potential for widespread
showers over most of the southern portion of the forecast area as
each day passes.

Moving into Tuesday, the pattern begins to shift as the longwave
trough slowly moves southwestward towards the North Pacific. As
it does so, the orientation of the trough and a ridge building in
from the North Slope and moving southward will cause most of its
energy to move over Southcentral in the form of easterly waves.
There are currently discrepancies from current model guidance in
the intensity of the waves over the region Tuesday afternoon, so
stay tuned for future updates as this system continues to develop.

-BS

&&


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

Unsettled weather persists through the weekend as several lows
merge southwest of Kodiak Island, sending pinwheeling upper level
shortwaves across all but the Western Aleutian Islands and Bering
Sea. One such wave will move through this afternoon and evening,
with another arriving for Sunday. Rain will be more widespread,
albeit light, with the wave moving through today. Meanwhile,
winds will be the primary threat for tomorrow; we continue to
expect gusts of 40-50 mph for interior Bristol Bay. Conditions
improve from Monday through Tuesday as the low near Kodiak Island
weakens and a ridge builds in from the west. The next system
approaches the Western Aleutians Tuesday afternoon, heralding a
return to more active weather after a spell of calmer conditions
for the Western Aleutians/Bering.

-KC

&&
.LONG TERM FORECAST (Days 4 through 7)...

Upper level ridging extends from northern Alaska into the Bering
Sea by mid week, with two upper level lows on either side, one
situated over the Western Aleutians and the other in the North
Pacific. Multiple shortwaves will cycle around the Pacific low and
move over Southcentral and portions of the Alaska Peninsula,
bringing rounds of rainfall through at least Friday. High pressure
dips south over Southcentral by next weekend which is likely to
bring about drier conditions. The system developing out west will
push its front across the Aleutians towards Southwest Alaska
through next weekend. Areas of small craft to gale force winds are
likely along the front as well as localized areas of heavy
rainfall. There is decent model agreement initially but
discrepancies quickly increase by next weekend.

&&

.AVIATION...

PANC...VFR conditions to persist. Mild northerly winds continue
to filter into the terminal but the expectation remains for winds
to increase in intensity through this evening while also
transitioning to a southeasterly direction. From this morning`s
discussion with a few updates, a pressure gradient between
Anchorage and the Susitna Valley should be strong enough to
briefly overcome a strong down-inlet pressure gradient developing
out ahead of a strong trough moving into the Kenai Peninsula from
the northern Gulf. Southeast gusts associated with a strong
Turnagain Arm wind clipping west Anchorage as strong as 30 kts
will be possible between 3z and 9z tonight. Winds bend away from
the terminal briefly late tomorrow morning before returning in the
afternoon with gusts closer to 15 knots.

BL/SB

&&


$$