654
FXAK68 PAFC 280040
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
440 PM AKDT Mon May 27 2024

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

A broad trough over the Yukon today will move slowly westward
over Alaska by mid-week. Satellite and radar show continued cloud
cover and rain across much of the Copper River Basin this afternoon.
Rain will persist overnight as northeasterly flow from the
aforementioned trough continues over the region. The heaviest of
the precipitation for the Copper River Basin will fall later this
evening and into early tomorrow morning as weak shortwaves move
through the area. Isolated rain showers are possible tomorrow
north and west of a line from Tok to Glennallen to Valdez as the
trough slowly moves eastward and the windflow becomes more
northerly; steadier showers are expected east of this line through
Wednesday with continued weak waves moving out of the Yukon.
These waves could continue through mid-week as the low currently
in Prince William Sound moves closer to shore reinforcing the
northerly to northeasterly flow for Valdez to Cordova during that
time.

Periods of scattered rain showers through mid-week are possible
in the Mat-Su Valley and Anchorage areas as northeast flow form
the aforementioned trough and PWS low impact Southcentral Alaska.
More widespread rain is expected Wednesday for Kodiak Island as a
front and short-wave approach from the south. The forecast for
Southcentral becomes more uncertain, with model differences in
track of another short-wave out of the Yukon into Southcentral.
There is potential for another round of steady rain across the
Copper River Basin Wednesday, with showers out ahead of it over
western portions of Southcentral.

-DJ

&&


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

Southwest Alaska is expected to remain dry through Tuesday as
weak high pressure ridges inland from the eastern Bering. This
will also maintain mild winds over the region through tomorrow.
A broad front extends southeastward from the western Bering into
the Eastern Aleutians. This front is bringing rain showers
this afternoon to the eastern Aleutians with southeasterly winds
gusting between 25 to 30 knots.

Into Tuesday a surface low is forecast to develop along the front
somewhere south of the Pribilofs. Enhanced southeasterly flow
will become more prominent through the Alaska Peninsula with
increased winds through gaps and passes. Across Southwest, a
shortwave trough lifting out of the North Pacific will promote
renewed shower chances from Bristol Bay into the Lower Kuskokwim
Delta and Lower Kuskokwim Valley. While thunderstorm chances are
less certain, it appears isolated wet thunderstorms will be
possible with the an area of weak instability developing over the
Middle Kuskokwim Valley late in the day. Any activity that does
develop should get carried northwestward within broad southeasterly
flow aloft.

Shower activity and winds over the Alaska Peninsula should
gradually diminish by Wednesday morning. The Aleutians and
Southwest should experience below normal temperatures and general
cloudiness while the low remains in place. By Wednesday afternoon
a surface low over the Eastern Aleutians will begin to weaken and
fall apart as the next system approaches the Western Aleutians
from south of the Commander Islands.

&&

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

The weekend opens with a decaying upper level low over the
Northeast Pacific that gets absorbed by a Western Aleutian low
as it moves across the Alaska Peninsula by Sunday. This second
low tracks to the East-Southeast through Monday. A broad trough
remains over most of the Bering and Southern Alaska through the
forecast. Model agreement is relatively good, opening with a
deterministic blend and transitioning to a one-half ensemble
means by the beginning of next week. Most of the active weather
continues across the Southern portions of the state.

Southcentral Alaska stays under persistent Southeasterly flow,
keeping a good mix of moisture moving inland to the Alaska Range.
Showery precipitation will continue through the weekend. More
active lows, fronts or troughs brings periods of rainfall across
the Aleutians, Bering and AKPEN, and into Southwest Alaska.
Northerly wind flow across the Western parts of the state
maintains lower than normal surface temperatures. Only the
Eastern Interior will see any warmer temperatures, with a upper
level ridge angled over the Central and Northern areas.

-Kutz

&&

.AVIATION...

PANC...VFR conditions will likely persist through the TAF period.
With a ridge building overhead and weak upslope flow with
southwesterly flow coming up Cook Inlet, ceilings will likely
lower with loss of solar heating this evening. There is a small
chance of MVFR ceilings overnight through Tuesday morning, though
the more likely scenario is low end VFR ceilings. Expect a
gradual lifting of ceilings during the day Tuesday with surface
heating and a shift to easterly flow at mountain-top level.

&&

$$