714
FXAK68 PAFC 041318
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
518 AM AKDT Thu Jul 4 2024

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

An upper level ridge now beginning to shift into the northern
Gulf is still anticipated to hold out just long enough for most of
Southcentral to stay dry for much of the July 4th holiday. Cloud
cover associated with an approaching frontal system out west will
continue to spill around the ridge and keep us from getting much
on the way of direct sunshine, but all but the Talkeetnas and
northern Susitna Valley will avoid any meaningful rainfall
potential until the tail end of the day. Light rain will fill in
from northwest to southeast as the weakening front crosses the
Alaska Range into the Cook Inlet region this evening, particularly
over higher terrain. West to northwest flow persisting in the
upper levels plus drier air in place in the lowest levels should
greatly limit how much rainfall reaches the ground near sea level.
Light rain should move into the Mat Valley and Anchorage by late
tonight, while much of the western Kenai Peninsula and Copper
Basin could stay totally dry into Friday morning.

A short break in the wetter pattern materializing is expected on
Friday as the front and upper shortwave push off to the southeast
and the ridging tries briefly to rebound behind it. Gap winds,
including through the Turnagain Arm and out of the Copper River
Valley, will also become stronger as southerly flow strengthens
ahead of a much deeper trough digging into the western Mainland.
Once again, don`t expect much of a break in the cloud cover, but
it should be a bit drier day overall, except for eastern portions
of Prince William Sound.

By Saturday morning, the second and likely more formidable
rainfall event will begin to take shape as a strong convergence
zone and moisture axis set up with southwesterly flow between the
trough moving into Southwest and the ridge still lingering over
the Gulf. Model guidance has struggled a bit with the placement of
the axis of heavier rainfall, with newer guidance suggesting an
axis from the Kenai Peninsula to the Prince William Sound could
take the brunt of the highest rainfall through Saturday afternoon.
Regardless of the exact details, the bottom line is that it looks
like a wet day just about everyone, and it`s a good idea to make
holiday weekend plans accordingly.

-AS

&&


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

The pattern shifts as a shortwave drops into Southwest Alaska
today and combines with a front tracking from the Bering Sea. The
pull of moisture from the front bring widespread wetting rains to
Southwest and south across the Alaska Peninsula through Saturday
morning. High pressure continues over portions of the Bering Sea,
bringing areas of patchy fog to the Central/Western Aleutians as
well as the Pribilof Islands.

&&


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

The long range models are in more agreement today with the
pattern change mentioned in previous discussions. The areas of
high pressure that have been persistent over the Bering Sea and
the Gulf of Alaska in the early part of the period will start to
break down allowing a North Pacific low to track northward into
the Gulf. This combined with troughs of low pressure transiting
across the Bering Sea and Kuskokwim Delta will track eastward
across the region through the end of the period. As a result,
expect scattered precipitation and cooler temperatures across the
much of the forecast area. Additionally, gusty winds and possible
small craft conditions are expected in Cook Inlet and coastal
regions of the Kenai Peninsula Saturday afternoon and into Sunday.

-DD

.AVIATION...

PANC...VFR conditions and light winds persist through tomorrow
morning. Westerly winds begin shifting southerly this evening as
Turnagain Arm winds strengthen ahead of an approaching front.
Southerly to southeasterly winds then increase by late Thursday
morning, with the potential for gusts 20-25 kt persisting through
the afternoon.

Light rain is expected late Thursday afternoon through Friday
morning, with minor uncertainty in timing. Ceilings will drop with
this rainfall, likely below 5000 ft, with some guidance even
dropping ceilings to MVFR.

&&


$$