660
FXAK68 PAFC 300027
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
427 PM AKDT Sun Jun 29 2025

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

The overall synoptic setup has changed little with overnight
guidance. In the upper levels, there is a deep, amplifying,
positively tilted, and digging longwave trough situated from the
Gulf southwestward into North Pacific. Within the trough envelope,
a broad, upper level low is quasi-stationary over the north-
central Gulf with several lobes or waves of vorticity rotating
around its periphery. The most relevant of these shortwaves is now
located near the Al-Can border, which is helping to initiate
showers and few isolated storms in the Copper River Basin, with a
steering flow causing storm motion to be northeast to southwest.
There is also a secondary upper level low centered in west-
central Alaska, which is helping to reinforce a northeast to
southwest flow across much of Southcentral.

At the surface, a slowly weakening occluded low is still sitting
and spinning across the north-central Gulf, which has allowed for
coastal ridging to sneak back into the picture, which has caused a
pressure gradient to develop, allowing the Turnagain and Knik Arm
winds to be gusty once again this afternoon. Radar returns depict
showers developing and moving out of the Copper River Basin and
into coastal regions such as Valdez, Cordova, and Tatitlek. It is
looking like that is where the main axis of precipitation is going
to continue to set up shop, with only a few showers to be felt
elsewhere closer to Anchorage and Palmer. The more clearing the
Copper River Basin sees this afternoon and evening, the more
likely the chance of storms to develop.

Later Monday through Tuesday, the Gulf low meanders eastward with
higher pressure filling in for Southcentral. Any showers that
linger will be near terrain. The next disturbance for Southcentral
will be possible around midweek from either the front that
reaches Southwest Alaska into the western Gulf and/or a shortwave
trough that stretches from the Northwest Territories to our
northeast to a southwest trajectory into Copper River Basin and
into Southcentral. While models are suggesting this, there are
plenty of synoptic players involved and a lot can change in the
details between now and then.

-McCormick/Rux

&&


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

An upper-level low situated near Galena this afternoon is sending
a shortwave trough southeast over the Y-K Delta, resulting in
scattered showers moving over the Kuskokwim Mountains. This wave
may also help to provide another round of isolated thunderstorms
this afternoon and evening near the Western Alaska Range north of
Lake Clark NP. Any storms that do develop, however,are expected to
be less widespread than yesterday. Any thunderstorms that are
able to develop will taper to showers by tonight as the next big
weather-maker arrives from the Bering Sea.

Focus then shifts west as a mature low emerging off of the
Kamchatka Peninsula pushes both a warm front and trailing cold
front across the Bering Sea and Aleutians to the Southwest Alaska
coast. The warm front approaching the Pribilof Islands this
afternoon will continue east tonight as the parent low advances
up the eastern coast of Kamchatka. A warm push of air along with
plentiful moisture from the tropical Pacific will accompany this
system. The front along with gusty southerly winds and moderate to
heavy rain at times arrives to the Kuskokwim Delta Coast overnight
Sunday into early Monday morning.

Rain works into Bristol Bay and the interior Kuskokwim Delta
through Monday morning and early afternoon. A reinforcing shot of
warm air and moisture get pulled northward into the Western and
Central Aleutians as well as the Pribilof Islands also on Monday.
This activity moves east to the Eastern Aleutians and southern
Alaska Peninsula (AKPEN) for Tuesday as the initial front begins
to occlude and moves further inland to the Kuskokwim Valley by
then. The heaviest rain looks to fall across the Kuskokwim Delta
Coast on Monday and across the Bristol Bay Coast, southern AKPEN,
and western Kuskokwim Valley for Tuesday.

In addition to the widespread rain, gusty south-southwesterly
winds will also accompany this system. Gusts of 35 to 40 kt are
possible by Monday afternoon for Unalaska Bay and Cold Bay.
Similar gusts are also possible across Kuskokwim Bay, likely
resulting in rough seas along with the potential of localized
areas of coastal erosion. The gusty winds will extend into the
Kuskokwim Delta, with winds gusting as high as 40 mph for Bethel.

Rain continues to linger across mainland Southwest through
Tuesday evening with the heaviest along the southern AKPEN as the
low tracks to the eastern Bering by then. Another shortwave then
looks to lift north ahead of the upper-level trough, bringing
additional rainfall to the AKPEN, Bristol Bay, and Southwest
Alaska coast into Wednesday.

A ridge builds in behind the low across the rest of Bering with
quieter weather across the Western and Central Aleutians Tuesday
evening as the Eastern Aleutians contend with northerly flow and
rain showers downstream of the ridge. Areas of fog are likely to
redevelop for the western Bering and Aleutians, underneath the
ridge.

-TM/JH

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

The long term forecast remains on track. A strong upper ridge
will build in over the northern half of Alaska through the end of
the week. This, combined with a persistent upper low in the
Alexander Archipelago will channel easterly waves through
Southcentral Alaska. This pattern will favor showers and
thunderstorms in the Copper River Basin and the Lower Kuskokwim
Valley for the end of the week including the 4th of July. The
Anchorage and Mat-Su Valley regions may see showers with chances
increasing the further north you go. The Kuskokwim Delta and the
western parts of Bristol Bay will also receive showers, but due
to the marine influence, thunderstorms are unlikely. The eastern
part of the Gulf coast from Cordova east will receive periodic
bouts of rainfall as the waves pass through. Meanwhile, the Bering
will start with slight ridging on Thursday, allowing for less
active weather. However, by Friday, a large low will swing in from
the west, increasing wind speeds and rain chances into the
weekend.

The weekend sees the upper ridge in the north flatten out. There
is quite a bit of uncertainty in how exactly this will play out,
but most guidance does agree that the ridge will weaken at some
point. As for our forecast area, the aforementioned large ridge in
the Bering will swing over into the Gulf of Alaska by Sunday,
bringing increased wind speeds and rain chances for first the Gulf
coast, then the rest of inland Southcentral by Monday. There is
good model agreement on this scenario with the main difference
being the exact track of the low when it moves into the Gulf of
Alaska.

&&.AVIATION...

PANC...VFR conditions are expected to continue. Scattered rain
showers will continue to work over the Chugach Mountains with the
potential for some showers to pass over the terminal. Shower
chances may increase Monday morning as another upper wave pushes
through enhancing activity spilling over the mountains. Ceilings
and visibility are expected to remain VFR but there is still the
potential for a brief dip in both for any shower that passes over.

&&


$$