436
FXAK68 PAFC 021245
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
445 AM AKDT Tue Jul 2 2024

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

Not much change to the overall pattern is expected for the next
couple days as a low meandering close to Kodiak pulls south into
the North Pacific and a weak ridge of high pressure spanning along
a west-east axis slowly builds over Southcentral through
Wednesday. A couple very weak waves rotating around this ridge
from the Yukon this morning will help set off areas of rain
showers across the northeastern half of the Copper Basin today.
None of this activity is looking too impressive, and little more
than a tenth of an inch of rainfall is expected for any part of
the Copper Basin before showers mostly dissipate by this evening.
Away from the briefly cooler and showery pattern setting up to the
northeast, it looks like a better afternoon at least is in store
across western parts of the outlook area. Scattered to broken
cloud cover in place this morning across the Mat-Su and Kenai
Peninsula is expected to erode somewhat with subsidence drying
around the developing upper level ridge drifting in from the
north. Despite the strengthening high pressure, low level flow
will remain south to southwesterly (especially near the Cook
Inlet), and this will tamp down highs in the low to mid 60s for
much of the region even with partial sun returning. Much of the
same is expected for Wednesday as the narrow ridge remains mostly
intact and the Gulf low moves even farther out into the Pacific.

By Thursday (July 4th), hints of a bigger pattern change will
begin to be felt by some. A series of shortwaves interacting with
a band of moisture streaming around the ridge from the Bering Sea
into the Interior will begin to encroach from the north, with a
stronger trough expected to approach the Alaska Range by the
afternoon. Increasing cloud cover will spread in from north to
south through the evening, with steady light rain also spreading
in ahead of the wave first into the Susitna Valley, then expanding
south towards the Matanuska Valley late in the evening.
Fortunately, it doesn`t look like a washout holiday for most, with
the best potential for rainfall holding off until very late in
the day for all but portions of the Susitna Valley.

-AS

&&


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

High pressure ridging builds over Southwest Alaska today, cutting
off precipitation for most areas but bringing in some patchy fog
and/or low ceilings along the coast today. Shortwaves riding
overtop the ridge will drop south into Southwest Alaska late
Wednesday night/early Thursday morning. This will allow for a
shift to a more rainy pattern beginning in the Kuskokwim Delta
before tracking eastward. Further west, a front extending off a
Kamchatka low moves into the western Bering Sea this morning,
bringing widespread rain showers to the Western and Central
Aleutians.

&&

.LONG TERM FORECAST (Days 4 through 7: Friday through Monday)...

The ridge of high pressure over Southcentral Alaska will start to
gradually weaken through early next week. This, coupled with an
approaching frontal system from the west, will produce a
southeasterly wind flow across the area. Cooler temperatures and
sporadic widespread precipitation over the region is possible over
the long 4th of July weekend. Precipitation should remain in the
mid to upper elevations but we cannot rule out intermittent rain
over much of Southcentral Alaska and the Copper River Basin
through Monday. Several troughs of low pressure extending from a
cutoff low in the North Pacific will bring some heavier periods of
precipitation across Kenai Peninsula, Kodiak Island and the
Northern Alaskan Peninsula through Monday afternoon. Out west, the
Bering/Aleutians and Southwest Alaska can also expect showery
conditions through the weekend as an upper-level trough and
multiple shortwaves rotate across the regions.

-DD

&&




.AVIATION...

PANC...VFR conditions expected to persist Tuesday into Wednesday
while weakening ridge of high pressure over interior Alaska sags
southward into the region. Light southerly winds in the morning
will gradually transition to a westerly direction this afternoon.
The Turnagain Arm wind should be largely absent for the first time
in several days.

&&


$$