983
FXAK68 PAFC 100159
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
459 PM AKST Thu Jan 9 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Saturday night)...

A complex low over the Gulf is currently wrapping into the
southeastern reaches of the forecast area (near the Copper Delta)
while a deformation band of mixed precipitation lingers over Cook
Inlet to the west. Rain will persist along the Gulf Coast and
especially across Prince William Sound into the weekend. Through
the remainder of tonight the low will continue lifting
northeastward with the deformation band to shift northeastward as
well. This will bring a chance for some additional light snow
across Anchorage and the Mat-Su through midnight tonight, though
don`t expect much in the way of accumulation. Anywhere from a
dusting to an inch or two is possible but, with the way the winter
season has continually teased Southcentral with possible snow,
it`s best to temper expectations. Moving into Friday, the
Anchorage Bowl and MatSu should see a brief break in
precipitation, but a warm front lifting up the western Gulf will
bring renewed precipitation in the form of a light rain/snow mix
by late morning/early afternoon.

Attention turns to the weekend when yet another upper low is
forecast to move into Cook Inlet. Models have trended more toward
a western solution with the track of the low, which unfortunately
means a wetter (rain instead of snow) and windier (Chinook
pattern) forecast on Saturday into Sunday. Gale southeasterly
winds look probable into the Barren Islands as well as into Prince
William Sound with gusts of 50 knots. Though less certain, the
easterly flow should once again be enhanced into Portage Valley
and the Eastern Turnagain Arm through morning hours on Saturday. A
Mat-Valley wind with gusts to 30+ mph will keep conditions
unsettled across the Valley.

-BL

&&


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

An active weather pattern continues for Southern Alaska as a
series of low pressure systems make their way through our region
tonight through the weekend. The first of these lows is a
Hurricane force North Pacific low, the center of which is just
South of Adak. The low is broad, spreading gale force winds from
Amchitka to Unalaska, with light to moderate rainfall and
rain/snow mix throughout the system. The progression of this low
center appears steady and is moving northeast. This low is
expected to bring storm force winds south of the low near the
eastern Aleutians late this evening into tonight. Gusts as high as
55 to 65 mph will be possible across parts of Unalaska as the low
passes to the north late tonight into early Friday morning,
particularly with winds funneling through terrain out of Captain`s
Bay. The broad arching front will spread from Unalaska late this
afternoon, and across the entire Southwest Alaska coastline by
early Friday morning, with potentially an initial push of
snowfall, transitioning to a rain/snow mix and eventually plain
rain by early Friday afternoon.

As the low lifts north towards Nunivak Island during the day on
Friday, the wind field will weaken to gale force, but will still
stay strong enough to cause possible impacts to the Kuskokwim
Delta Coast. Onshore winds could gust up to 40 mph as the low
approaches to the west from Friday afternoon into Friday night.
While there is more sea ice in place along the coast compared to
what we had for the last coastal flood event, there may still not
be enough stronger, shore-fast ice to protect coastal communities
from a possible storm surge with this low. Even where stronger ice
exists, water could pool up through cracks and cause localized
flooding for communities along the immediate coast near high on
Friday evening. Confidence on the degree of flooding is low, but
concern is high enough to justify issuing a Coastal Flood Advisory
for the Kuskokwim Delta Coast, which remains in effect starting
midday Friday. The low driving this will begin to weaken Saturday
morning, and exit into the northern Bering Sea late Saturday.

Attention from there quickly shifts to the next strong low setting
up along the active storm track continuing into the weekend. By
late Friday night, another potentially Hurricane force low will
approach Kodiak Island. The center could briefly head up into
Bristol Bay before it veers more northeast towards Southcentral on
Saturday. The main impact across Southwest will be another round
of gusty southwest winds moving in behind the low passage,
especially over southern parts of the region close to Bristol Bay
and the AKPen. Moderate rain and snow will also move north with
the low Friday night into Saturday morning, though temperatures
appear likely to remain too warm for significant snow
accumulation.

If all that wasn`t enough to handle, an even stronger, larger low
pressure system will begin to move up into the eastern Bering Sea
from the Pacific from Saturday into Saturday night. Very strong
southeast winds will spread into Southwest through the Kamishak
Gap into the greater Bristol Bay region along with locally heavy
rain/snow moving back across much of the area as well. Strong
north winds up to Storm force could also move into the eastern
Aleutians and Pribilofs west of the low, where temperatures could
remain cold enough for mostly snow to fall, especially up towards
the Pribilof Islands. Cold air pulled down on the western side of
the low may initiate gusty winds in the Pribilofs along with the
snowfall, however confidence for now is low on the precise low
position. Stay tuned as we continue to monitor this active pattern
and the many impacts expected around our region.

-CL/AS

&&


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

A very active weather pattern continues across Southern Alaska
through the forecast period. The upper longwave trough over the
Bering gains energy from several shortwaves and reorients over
Mainland Alaska into the Gulf of Alaska by Thursday. These
shortwaves support a well developed surface low moving through the
Bering Strait into the Russian Arctic, with its associated front
extending across Western Alaska and along the Southcentral coast.
Deterministic GFS, ECMWF and Canadian models carry the features
and changes well through Tuesday before the ensemble means take
over through the week.

Cold air from the backside of the low keeps areas of snow and
gusty winds across the Bering into Southwest Alaska, Pribilofs and
the Northern Alaska Peninsula. The warm sector weather presses
locally heavy rains and gusty winds along the Southcentral coasts,
with areas of locally heavy snow over inland and higher
elevations through Monday. An Eastern North Pacific low tracks
into the Copper River Delta for Tuesday before slipping into
Prince William Sound and dissipating late Tuesday, prolonging the
heavier precipitation and gusty offshore winds for that area. A
new North Pacific low and front spreads areas of moderate rain or
rain and snow mixed over the Eastern Aleutians Tuesday, becoming
areas of heavy rain or rain/snow mixed over the AKPEN, Kodiak
Island and Southwest Alaska through Thursday. A second Eastern
North Pacific low brings snow to the Southcentral coasts before
changing to rain later on Thursday.

&&

.AVIATION...

PANC...A band of precipitation will push off to the west this
afternoon, though some light rain or a rain snow mix may continue
to fall at the terminal between 0 and 5Z. The band will then push
back into Anchorage this evening to later tonight, leading to some
light snow accumulation. Conditions are expected to be VFR to
MVFR this afternoon to early this evening, then possibly becoming
IFR as the snow moves in. Saturation will then likely keep clouds
in the MVFR to IFR range through tomorrow afternoon. Winds will
be mostly light overnight, becoming southerly tomorrow. Total snow
accumulations of 1 to 3 inches possible, but may have difficulty
accumulating until later tonight.

&&


$$