426
FXAK68 PAFC 010054
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
454 PM AKDT Wed Sep 30 2026

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

Aside from areas of wintry precipitation across Southcentral,
there are quite a few marine lightning strikes to speak of across
the far northern Gulf near Cordova due to some instability
associated with colder air moving in aloft and a surface low
located over the north-central Gulf. This activity is located
downstream of relatively broad troughing over much of Alaska,
allowing for additional lift and steeper/steepening lapse rates.
These isolated thunderstorms will move eastward towards Yakutat
through tonight, and has been reflected in marine products with
this afternoon forecast package.

The big story is lower elevation rainfall with a few flakes mixed
in and higher elevation snow continuing this afternoon across the
northern Cook Inlet region northward into the Matanuska Valley.
Precipitation type has not only been elevation driven, but also
intensity driven as well. Even in places where the predominant
precipitation type has been rain today, there have been flakes
mixing in with heavier precipitation rates just a few hundred feet
up in elevation. The forecast largely remains on track as we
continue to watch the progression of two trough axises; one
negatively tilted trough stretching from the Cook Inlet region
into the Gulf and lifting northward and another digging
southeastward over Southwest Alaska to the west. The main forecast
challenge over the course of the short term will be honing in on
how quickly these two features phase as the first trough continues
to lift towards the southern Copper River Basin as the second
trough moves south and eastward through this evening and
overnight. The GFS has consistently been the slower solution, and
lingers the secondary trough over Southcentral for longer, which
in turn would keep precipitation chances around through Friday
morning or so. Although the GFS is starting to look more like an
outlier compared to other deterministic models that bring
precipitation out of the region faster, its consistency increases
forecaster confidence that precipitation will linger for longer
than what the EC and some of the other models currently depict. If
the GFS is "more correct" than the other models, and should
showers train over the higher elevation areas like Glen Alps or
South Fork tonight, up to 5 inches of snowfall will be possible.

By Thursday morning, the southern most trough axis will move into
the southern Copper River Basin, the Panhandle, and Yukon
Territory, while an arm of the notably colder upper low/trough
moves southward over the western Alaska Range and greater Bristol
Bay area. This will continue to provide lift for showers along the
Chugach and Kenai Mountains, with some precipitation possible for
Anchorage and the Matanuska Valley. By this time, the airmass
aloft will be quite cold, dropping snow levels as low as 800 ft or
so. It is not out of the realm of possibility for some near sea
level areas from Anchorage north to Palmer to see some snowflakes
Thursday morning if a heavier shower moves overhead and mixes
colder air down closer to the surface. Areas along the upper
Hillside and South Fork Eagle River are likely (60 to 70 percent
chance) to get a dusting up to 3 inches depending on the elevation
and intensity of the showers. By Friday morning, precipitation
should be out of the area, and with clearing skies, the first hard
freeze with temperatures less than 30 degrees is likely for many
of the population centers.

AM/CJ

&&




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

Key Messages:

* Sub-freezing overnight temperatures in Southwest Alaska
  throughout the week.

* Rain and gale-force winds spreads eastward across the central to
  eastern Bering/Aleutians through Friday. Another, slightly
  stronger front enters the western Bering/Aleutians Friday night
  and its accompanied low treks through Saturday morning.

Discussion:

As the northern periphery of a low pressure system, south of the
Aleutian Chain, skirts across the Aleutians to the Alaska
Peninsula, expect widespread rainfall and generally windy
conditions through Friday evening. Meanwhile, a stronger Kamchatka
low with its attendant front reaches the western Bering Sea and
Aleutians Friday night. Additional rainfall is expected to
continue for the Aleutians. Although it appears to be a stronger
than the previous, gale force sustained winds are expected at this
time. On the back side of the front and wrapping around the parent
low, winds could increase to storm force (with a 35 to 50 percent
confidence).

As the upper level trough moves east tonight, ridging will build
across Southwest Alaska. Northerly flow and relatively dense,
Arctic air will allow for relatively clearer skies and ultimately
colder temperatures. Daytime high temperatures will struggle to
get out of the 40s with nighttime/morning lows in the 20s. A few
isolated spots farther inland could even touch the upper teens.
The minimum temperatures will be highly dependent upon cloud
cover. None-the-less, skies should generally continue to clear
over the next couple of mornings. Temperatures across the AKPEN
should stay above freezing through the week. This weekend into
next week, temperatures will slightly rebound toward more
seasonably normal temperatures.

&&

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

No change from previous discussion... Looking ahead toward this
weekend, models are synoptically in good agreement in the mid-
range forecast, featuring a low moving toward Kodiak Island from
the North Pacific and another low into the Bering Sea from the
west. Precipitation with east to southeast winds will be more than
likely for Southcentral, especially closer to the Northern Gulf
coast and Kodiak Island. By Sunday, the front extending from the
Bering Sea low reaches Southwest Alaska and the Alaska Peninsula
bringing rain, snow, and southerly flow across the area. As the
low sinks southward Monday, models diverge on how far south the
low will dip. Generally, the low appears to pass through the
Alaska Peninsula and near Kodiak Island/Western Gulf. As this
pattern sets up through the first half of next week, cold air
advection and northerly winds will become enhanced through gaps
along the Aleutians. If the low sinks south farther east, the
Alaska Peninsula would see more cold air advection and those
northerly winds. While temperatures overall for southern Mainland
are trending cooler in the short term, some moderation of that
trend is expected toward more seasonable norms, but will remain on
the cooler side.

&&

.AVIATION...

PANC...Periods of low clouds and occasional rainfall will linger
into this evening and into at least the first half of tomorrow as
a trough gradually crosses the area. CIGs may oscillate between
IFR and MVFR through the duration. Winds will generally remain out
of the north, though may become light/variable at times.
Precipitation will taper off Thursday evening (after 00z) in wake
of the trough, though lingering low-level moisture may trap low
clouds for a little while thereafter.

&&

$$