Mill Bay, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

880
FXAK68 PAFC 091335
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
535 AM AKDT Wed Apr 9 2025

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

Discussion:

The upper low that dropped south across Southwest Alaska yesterday
has now moved to just east of Kodiak Island of of early this
morning. On the south side of this low, an elongated trough is
digging across the southern Gulf and North Pacific with models in
good agreement with lifting it towards Southeast Alaska on Thursday.
Another trough and associated front are rotating around the northern
side of the parent low with colder temperatures filtering northward
across the northern Gulf behind the aforementioned front. Cold mid-
levels has resulted in scattered rain and snow showers over the
Gulf with more steady precipitation along the front as it begins
to move inland. Cordova has seen a switch to snow this morning as
this band moves through. Seward, Whittier, and Valdez are still
warm enough ahead of the front for all rain, but as colder
temperatures begin to filter in...these locations should also see
a change-over to all snow. However, gusty winds moving into
Western Prince William Sound may allow for periods of mixed
precipitation for Whittier. Depending on how quickly these
locations change-over to snow and the showery nature will
determine how much snowfall accumulates. But it is looking likely
that Seward could see about 2 to 4 inches today as southerly flow
develops. Turnagain Pass and Whittier could see around 5 to 8
inches. As the colder air and snow spreads inland across the
Chugach Mountains, Portage Valley could see snow accumulations of
6 to 10 inches with gusty winds. While there is some uncertainty
in amounts and initial precipitation type at some locations, we
have seen over the past few days that these more convectively
driven snow bands result in good snowfall rates allowing for
snowfall to rapidly accumulate. As such, have gone ahead and
issued a Winter Weather Advisory in include Turnagain Pass,
Portage Valley, Girdwood, and Whittier for later this morning
through Thursday morning.

The parent Gulf low will weaken into an open wave tonight as it
lifts north towards Prince William Sound. This will allow another
round of snow showers the eastern Kenai, Prince William Sound, and
the coastal mountains. Thompson Pass could see up to a foot or
more of snow through Thursday night.

With troughing over western Alaska and the shortwave trough lifting
over the northern Kenai and Prince William Sound, expect the ongoing
band of snow extending from the southern Kenai Peninsula northward
to continue through at least early afternoon. A Winter Weather
Advisory remains in effect for the southern Kenai Peninsula this
morning.

- PP

&&


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

A generally unsettled weather pattern will persist through this
forecast period. Conditions will continue to improve along the
Alaska Peninsula this morning as a low exits into the Gulf. This
will quickly be followed by a shortwave moving across the Bering
Sea today, bringing another round of light snow to the Eastern
Aleutians and Alaska Peninsula, with the potential for rain to
mix with snow as temperatures rise above freezing in the
afternoon. Parts of Nunivak Island, Kuskokwim Delta, and Kuskokwim
Valley will likely also see some light snow as a weak upper level
shortwave moves through. Otherwise, expect clearer skies, lighter
winds, and cool temperatures for Southwest Alaska.

Forecast confidence diminishes tomorrow night and into Friday as
another shortwave trough dives into the Bering Sea from Russia.
There`s uncertainty with how this trough will interact with an
upper low near the Seward Peninsula and, therefore, the
positioning of the resultant surface low. The overall impact of
this uncertainty is fairly small, mostly affecting the forecast
for the Northern to Central Bering Sea, Pribilof Islands, and
Kuskokwim Delta. The latest model run of the NAM keeps the surface
low in the central Bering, suggesting quieter weather for
Kuskokwim Delta. The Canadian model is tracking the system further
west over Nunivak Island while the GFS and ECMWF fall somewhere
in the middle. We will keep a close eye on how this system
progresses going forward.

Further south, a North Pacific low and its front skirt the
southern side of the Aleutian Chain as it works its way east on
Friday, gradually pushing out the ridge of high pressure that sits
across the Western and Central Aleutians through tomorrow. There
are still uncertainties with the system`s exact positioning, which
will affect forecast winds and precipitation chances along the
Aleutian Chain. A surface low looks to form along the front and
track over the Alaska Peninsula early Saturday morning, bringing
enhanced winds and precipitation to the region as it moves north
into Bristol Bay.

-Chen/TK

&&


.LONG TERM FORECAST (Days 4 through 7: Saturday through Tuesday)...

A well developed closed upper low over the Northern Bering begins
its sweep across the Alaska Peninsula into the Gulf of Alaska and
Eastern North Pacific by Tuesday. This center runs through an
elongated negatively tilted trough and slowly weakens through the
period. It is also dragging considerable colder air with it. Throw
in a number of shortwaves passing over the Aleutians and
generally unstable conditions will be spreading from the Central
Bering across Southwest Alaska. A generalized blend of forecast
models covers the larger scale features, but uncertainty remains
high in the unsettled pattern and smaller details.

A developing surface low to the South of the AKPEN spread areas
of moderate snow and gusty winds from the Eastern Aleutians and
AKPEN into the Central Bering on Saturday. The snow will change to
moderate rain over the AKPEN and Bristol Bay, spreading over
Kodiak Island and along the Southcentral coastal zones as the low
gets stronger across Bristol Bay. Winds increase to gale force
late Saturday over the Eastern Bering, and through the Barren
Islands into Kamishak Bay late Saturday and extend along the
Southcentral Coast through Sunday. A weak surface and front push
across the Western Aleutians Sunday. Locally moderate snow extends
along the West Coast and over the Eastern Bering. As this surface
low slips back across the AKPEN, mostly snow remains and slowly
dissipates in the West by Tuesday. Moderate to heavy rains move
from Kodiak Island into the Eastern Kenai Peninsula, and Western
Prince William Sound, diminishing Tuesday.

- Kutz

&&

.AVIATION...

PANC...Vicinity showers and flurries will continue throughout
today with mostly VFR to MVFR conditions expected, accompanied by
5-15 kt southeasterly Turnagain Arm winds. Brief periods of more
intense snowfall rates along with IFR to LIFR conditions are not
out of the question, but there is also less confidence in exact
placement of snow bands that develop. Up to a 0.5" is possible
through Wednesday afternoon, while winds shift to light and
northerly Thursday morning.

-AM

&&
$$