770
FXAK68 PAFC 181251
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 AM AKDT Sat Oct 18 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA
(Days 1 through 3: This afternoon through Monday evening)...

An upper-level trough is currently stationary over the Copper
River Basin this morning. Situated at the base of this trough, a
compact vertically stacked low is spinning just north of Montague
Island. This feature, combined with lift and cold air advection in
association with the larger trough, is driving moisture across
the Sound northward into the western half of the Copper River
Basin. This moisture is wringing out in the form of snow across
the western and northern portions of the valley, with the heaviest
snow, on the order of 2 to 4 inches, falling along the Glenn
Highway west of Glennallen. Farther west, colder and drier air is
spilling south through the Susitna Valley. Lingering moisture
along the foothills of the Chugach and Talkeetna Mountains is
resulting in areas of fog and low stratus from Willow south to
East Anchorage.

The aforementioned compact low will move south through this
morning as the larger upper-level trough slides east toward the
Al-Can border. As it does, the snow will taper from east to west
across the southern Copper River Basin, but not before an expected
snowfall total of 2 to 6 inches, with the highest amounts around
Eureka. The combination of the low moving south, cold air
advection, and a ridge of high pressure building over the
interior, will drive gusty gap winds out of Seward, Whittier,
Thompson Pass, and the marine zone complex of Valdez.

While gusty northern gap winds through Thompson Pass and Valdez
Narrows persist into Monday, northerly surface flow should inhabit
really gusty conditions from getting into Whittier by Sunday. A
light easterly component is even possible for Passage
Canal/Whittier Sunday as the pressure gradient reorients. Whittier
winds and Passage Canal winds look to pick back up from the west
on Monday as a front lifts towards the Gulf Coast by then.

Speaking of the aforementioned front lifting towards the Gulf
Coast for Monday, the parent low pressure to this front continues
to trend more northward compared to previous model runs. As a
result, Kodiak Island will be wetter and windier Sunday night into
Monday with most of the heavy rain being confined to the Gulf
waters. Rain looks to also reach the Eastern Kenai Peninsula and
Western Prince William Sound Monday morning with rain perhaps
clipping portions of the northern Gulf Coast as well. The
strongest winds still look to remain on the southern flank of this
system in the North Pacific with some gale-force gusts over the
Gulf waters; however, easterly gales are also looking more likely
along the front as it lifts into the northern and western Gulf.
This system moves to the eastern Gulf and Southeast Alaska by
Monday evening. Stay tuned to further forecast updates as details
become more clear regarding this next frontal system for Sunday
and Monday.

-TM/DAN

&&


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

As of this morning, a surface trough is situated from northwest-
southeast across Unalaska and King Cove as a surface ridge slides
eastward across Southwest Alaska. A compact low looks to develop
within the trough envelope and bring showery and breezy weather to
the Pribilof Islands through this afternoon. Meanwhile, farther
west, weak transient ridging across Adak and Amchitka is eroding
away as a 1007 mb occluded low and its front move eastward and
away from the Western Aleutians.

The global models have trended a bit northward with the
advertised deep North Pacific low, which in turn will nudge and
bring easterly/northeasterly small craft and gale force winds
closer to Atka, Nikolski, and Unalaska for this evening into early
Sunday morning. If the current guidance holds / or keeps trending
northward, these winds will expand in coverage Sunday morning.
Likewise, confidence has increased that rainfall begins this
afternoon for these areas through Sunday morning as the northern
most portion of the low`s precipitation shield sideswipes the
Central and Eastern Aleutians.

With high pressure taking center stage across Southwest Alaska
Sunday morning, clearing skies and decreasing winds will allow for
some coastal and interior valley locations to bottom out in the
low to mid 20s for overnight lows. As the aforementioned surface
low tracks south of the area and deepens, its upper level low
component will amplify the 500 mb pattern, allowing for upper
level ridging to build in from the southeast. At the surface, cold
air advection from the light northerly to northwesterly flow
looks to be roughly on par with some of the coldest air so far
this season for the region. As the surface low tracks just south
of the Aleutians and Alaska Peninsula through Sunday
afternoon/evening, northwesterly winds in its wake will act to
reinforce cooler temperatures across Southwest Alaska.

Meanwhile, a secondary low pressure system works across the
Western Aleutians Sunday afternoon, bringing another round of rain
and windy conditions. As the low moves eastward towards Adak and
Atka, the global models have the system weakening and evolving
into a complex low as the 500 mb pattern becomes increasingly de-
amplified and flatter through Monday morning.

The latest runs of the GFS, EURO, and Canadian all show a potent
upper level wave and closed low drifting southward from the Bering
Strait and over Southwest Alaska Tuesday morning. There are
subtle differences in timing and placement of this feature, and
the GFS currently wants to develop a surface low Tuesday evening.
This will be one to watch for potential precip chances mid week.

-AM

&&


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

Upper level troughing over Mainland Alaska and a broad surface
low in the western Gulf of Alaska early this week will progress
into the eastern Gulf of Alaska through midweek. While relatively
good model agreement indicates most energy and associated rainfall
with this system will be directed towards southeast Alaska,
periods of rain can still be expected along the immediate coast
for the eastern Kenai Peninsula and Prince William Sound as
several weak perturbations rotate north into the northern Gulf
Coast. Eastward progression of this storm in the Gulf will promote
gusty northwesterly winds across the AKPen for Wednesday into
Thursday, with a cooler airmass spreading across the Bering and
much of the Mainland.

Guidance points to the jet stream becoming more zonal in the
North Pacific and in the Gulf of Alaska late in the week. Multiple
areas of weak low pressure across the Bering Sea, North Pacific,
northern Gulf of Alaska will keep much of the region under a
generally showery regime. Exact placement of these lows remains
uncertain and inconsistent, but confidence remains moderate that
the pattern remains rather progressive in the zonal flow.

&&

.AVIATION...

PANC...Predominantly VFR conditions and light northerly winds are
expected through the TAF period. There is a chance for a brief
period of MVFR conditions and patchy vicinity fog are possible
early this morning.


&&


$$