469
FXAK68 PAFC 021319
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
519 AM AKDT Tue Sep 2 2025

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

Discussion:

The ridge that was over portions of Southcentral yesterday has
shifted east with the primary axis tilted NE to SW as a shortwave
moves up into interior Alaska. While the front has also shifted
east, it has once again stalled as the ridge prevents it from making
additional movement eastwards. This has shifted the main precip
axis eastwards as well...generally extending from Kodiak Island
towards the Copper River Delta. Behind the front, there are areas
of drizzle and light showers from the AKPen up through the Susitna
Valley. A low sitting off the coast of Washington and Oregon will
begin to retrograde back to the west, helping to squish the ridge
even more. The ridge will build back over portions of
Southcentral Wednesday in response to both the retrograding PacNW
low and a trough lifting north towards the southern AKPen out of
the north Pacific.

Once again, moisture transport will be focused in between the systems
with another round of rain moving up across Kodiak Island, Cook
Inlet, and Mat-Su Valley on Wednesday. More widespread rain will be
focused over the northern Susitna Valley where another inch of rain
is possible as the parent trough moves up towards the Kuskokwim
Delta.

- PP

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA / BERING SEA / ALEUTIANS
(Monday to Thursday)...

Overnight rainfall is gradually shifting east of the region this
morning, though light showers are still falling from King Salmon
up into Iliamna. This activity should steadily diminish as the
remnants of a front/trough slide off to the east. Further to the
north, an upper trough is digging across the YK Delta with gusty
southerly winds ongoing across Nunivak Island and the Kuskokwim
Coast. Southwest winds gusting as high as 25 to 30 mph will likely
persist through midday before tapering off this afternoon. As a
result of the upper trough exiting Southwest into interior Alaska
and the remnant front/trough pushing east of the Western Alaska
Range, the second half of Tuesday is expected to be relatively
pleasant with dry weather and light winds. Cloud cover is more in
question, though it is likely that many areas across Southwest
will see some breaks over the Kuskokwim Delta and western portions
of the Kuskokwim Valley at times today.

All attention then turns to the next system that is expected to
move into Southwest Alaska later this evening/tonight. A North
Pacific low now south of the Eastern Aleutians will spread a front
over the Alaska Peninsula later this evening with increasing rain
chances. Initially easterly winds along the front will transition
to southeasterly behind the front, with gusty southerly gap winds
to develop across the Alaska Peninsula behind the front. Models
have come into better agreement with the placement timing of the
North Pacific system. Greater confidence exists with the center of
the low lifting northeastward across the Aleutians near Unimak
Pass and west of Cold Bay roughly around 4AM Wednesday morning. As
the low continues into the Kuskokwim Bay on Wednesday another
round of widespread rainfall is anticipated across Southwest
Alaska. This next round of precipitation will be lighter and
shorter in duration, with the bulk of rainfall only clipping the
Bristol Bay area and instead moving across the Kuskokwim Delta
through Wednesday morning and afternoon.

Beyond Wednesday the next low pressure system, yet another North
Pacific low, will be approaching the Western Aleutians. Forecast
models take this low into the southern Bering by Friday with its
front sliding across the entire Aleutian Chain during the same
time period. Thus, an active pattern looks to continue for the
Bering and Southwest. Precipitation chances will again arrive to
Southwest Alaska on Friday and continue into the weekend.

-BL

&&

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

True to early September, the weather will remain active for much
of Southwest and Southcentral Alaska through the weekend into
early next week. For the period beginning on Thursday night, the
pattern will be characterized by a ridge across the eastern Bering
Sea into the North Pacific and western Gulf of Alaska, with a
strong low across the Aleutians, likely centered somewhere near
the Rat Islands, and moving northeastward in the direction of the
Pribilof Islands. Meanwhile, Southcentral Alaska will be under the
influence of a departing trough. Rain will likely be diminishing
across Southcentral AK Thursday night into early Friday, with the
greatest uncertainty in how quickly it clears up depending on the
low timing.

Attention turns towards the gale-force low in the Bering Sea
Friday and Saturday as it treks northeast towards the Pribilofs
and then Southwest Alaska. The Aleutian Chain gets the worst of
the weather from this system as the attendant fronts draw
northward an atmospheric river from the North Pacific which will
bring heavy rain and strong gale-force winds to the chain as it
sweeps across.

Model agreement is surprisingly good with this system, suggesting
a `landfall` of the low near Nunivak Island Saturday evening,
weakening to somewhere in the vicinity of 995mb as it does so.
There`s also decent agreement that, while the first half of the
weekend might be dry for Anchorage and the rest of Southcentral,
precipitation then overspreads SC AK late Saturday and Sunday as
moisture is drawn northward from the North Pacific. At this time,
this looks like a widespread wetting rainfall, but the good news
is that the numbers/probabilities aren`t quite lighting up as an
anomalously heavy rain as we experienced at the end of last week.

What reasonable model agreement we had before is lost by the
start of next week. There are some signals of another strong low
marching across the Bering, while some models signal at a lower-
amplitude wavetrain. Either way, it`s September in Alaska- be
prepared for rains to glisten the yellowing foliage.

-Brown

&&

.AVIATION...

PANC...Off and on showers will persist this morning, along with
MVFR ceilings at times. Ceilings will rise and become
predominantly VFR by late morning. However, 5,000 foot ceilings
could linger with light southerly flow in the lower levels and
continued moist southwesterly flow in the middle to upper levels.
Southeasterly Turnagain Arm winds will also shut off early this
afternoon with winds becoming light and variable. A front lifts
northward across the western Gulf for Wednesday morning bringing
the chance for another round of showers across the terminal.
Ceilings look to remain VFR Wednesday morning, but around 5,000
feet with a lower deck developing at times. Flow should be
predominantly down-inlet Wednesday morning with light north winds
across the terminal and winds in Turnagain Arm bending down-inlet
as well.

&&


$$