973
FXAK68 PAFC 081330
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
530 AM AKDT Mon Jul 8 2024

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

Southcentral is sandwiched in between an elongated low stretching
into the region from well south of the Gulf to the Kenai and
Chugach Mountains. At the same time, a weak 500 mb trough is in
the Susitna Valley and will be moving eastward through the area
today. This setup is causing a persistent band of rain to have
developed over the northern part of Knik Arm and the Matanuska
Valley this morning. This rain may persist through much of the
morning until the 500 mb trough passes to the east. By late Monday
night, the low in the Gulf will push a front to the northern Gulf
and bring widespread rainfall along the coastal areas late
tonight into Tuesday. This rainfall is not expected to push very
far inland as the increasing pressure gradient increases southerly
gap winds in the typical locations and there will be enough
downsloping to keep inland areas with less chance of rain than
today. While the pesky and persistent upper level low that has
been along the northern coast of the state moves eastward late
today, on Tuesday, another upper level low will dig southward from
the Arctic Ocean into the Bering Sea. At this time it looks like
the bulk of the rainfall from this system will occur over
Southwest Alaska for Tuesday and Wednesday. However, most of
Southcentral will remain in this cool, damp, and cloudy pattern
through the middle of the week.If one is looking for a respite
from this August-like pattern, the one area that may see some
break in the cloud cover is the Copper River Basin from Tuesday
night into Wednesday morning.

&&


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

A blocking low located over the Gulf of Alaska will budge little
over the coming days. Immediately to its northwest, weak high
pressure is persisting over Southwest Alaska. Meanwhile, a compact
low north of the Central Aleutians has transitioned into an open
wave trough and will cross over the Aleutians into the North
Pacific through tonight.

Dry conditions and light southerly winds will start the day
across Southwest Alaska, though low stratus and areas of fog have
been observed on satellite beneath high pressure aloft. High
pressure will break down over the second half of the day as a
shortwave trough, evident on water vapor imagery over the Bering
Strait, dips across the region later this evening. Increasing rain
showers are forecast to expand into the Kuskokwim Delta and the
Lower Kuskokwim Valley. The trough`s eastward movement and a
broader front sagging across all the way into the southern Bering
will see widespread showers by Tuesday across Southwest Alaska,
along with developing gusty southwesterly winds ahead of the
trough and front.

Further west, isolated to scattered showers will be possible as
the aforementioned open wave trough crosses the Aleutians on its
way into the North Pacific. However, conditions should dry out by
this afternoon and evening as temporary high pressure resumes
across the southern Bering. The next shortwave trough tracks into
the Western Aleutian on Tuesday in concert with a broad front
extending across the southern Bering and into Southwest Alaska.
Thus, late Tuesday will likely see rain showers spanning the
Aleutians and much of Southwest Alaska. Shower activity continues
across the Western and Central Aleutians on Wednesday with yet
another trough into the region. The rest of the Aleutians dry out
as the previously mentioned front continues southeastward into the
Pacific and western Bering. High pressure lingering over the
Western Alaska Range on Wednesday will see the bulk of shower
activity for Southwest Alaska confined to the Kuskokwim Delta and
Bristol Bay regions.


-BL

&&

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

The upper level Alaska Weather map opens with a closed low over
the Northwest Bering that will shift towards the Western Alaska
coast by the end of the forecast period. A weakening low near
Kodiak Island is absorbed into this low, and results in a broad
low that stretches from the Russian Far East into the Western
Alaska Mainland by Sunday. A weak ridge holds across the Eastern
Interior of the state, supporting surface thermal troughs and
local convection through the weekend. Forecast model spread is
reduced through the period. Southcentral Alaska is sustained with
considerable moisture and areas of rain from the Alaska Range
South. Some areas may experience briefly heavier rains through
Sunday. A well developed surface frontal system brings locally
heavy rains over the Aleutians and Bering through Saturday. An
increasing area of heavier rains sets up from Nunivak Island and
the West Coast Late Friday, and spreads inland and across the
Alaska Peninsula by Saturday. Heavier rains move over Kodiak
Island and the Southern Kenai Peninsula late Saturday and Sunday.
This area of heavier rains continues across the Southcentral
Coastal zones beyond the end of forecast period.

- Kutz

.AVIATION...

PANC...MVFR or low VFR ceilings will persist through this
afternoon and into this evening. A weak Turnagain Arm wind will
persist over the terminal through Monday evening.

&&

$$