Gale Warning 658, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
502 PM AKST Tue Nov 28 2023

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/This
afternoon through Friday afternoon)...

Few major changes to the forecast as things remain largely on
track. Wet and windy conditions were felt today across much of
the region as a compact low moved through Southwest Alaska. With
the low continuing to move north, winds have already begun to
weaken across Kodiak Island. In other parts of Southcentral
Alaska, winds should be at or nearing their peak. Winds today have
remained largely as forecast, gusting to about 30-40 mph in
Matanuska Valley and as high as 45-55 mph along the Anchorage
Hillside. Expect these winds to gradually diminish from late
tonight through early tomorrow morning as flow backs from
southeast to northeast ahead of an incoming storm system.

Overall, not too much has changed with the deepening low and its
front, which will move into the Gulf of Alaska late tonight and
linger through Wednesday. There remain some model differences with
the track of this low, but confidence has increased enough for a
Winter Weather Advisory to be issued for Turnagain Pass for snow
and, potentially, blowing snow. Eastern Kenai Peninsula will
likely see precipitation for much of the day Wednesday with this
front, with the heaviest precipitation rates expected from
Wednesday afternoon through evening as the front moves inland.
Snowfall rates could reach or exceed 1 inch per hour in Turnagain
Pass during this time period. While warmer temperatures will
likely keep this as a wetter and heavier snow, there may still be
visibility reductions due to heavy snow and/or gusty winds. No
matter what happens, confidence is high that Wednesday will be a
wet day along the north Gulf coast; satellite imagery shows
precipitable water values of 0.5 to 1 inch with this system, which
is quite moist for this time of year. Areas away from the coast
may see a bit of precipitation, but most of it should be limited
to Eastern/Southern Kenai Peninsula and Prince William Sound.

-KC

&&

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

A compact low is currently moving north through the Lower
Kuskokwim Valley, bringing a mixture of rain, snow and wind to
much of interior Southwest. An additional one to two inches of
snow is expected this evening for interior areas before the system
departs to the north. Behind the low, weather will become quieter
with a return to more seasonal temperatures as colder air moves
in from the Bering. A few weak shortwaves and instability aloft on
Wednesday will generate coastal snow showers for the Kusko Delta and
Alaska Peninsula, otherwise broken skies and decreasing
temperatures will prevail for southwest through the early part of
the weekend.

Weather over the Bering will get increasingly active as a front
extending off of a low currently south of Kamchatka reaches the
western Aleutians tomorrow morning. Models are then indicating one
or more additional lows developing along the front as it extends
east towards the eastern Aleutians late Wednesday night. Depending
on the location of these lows, isolated areas with storm force
gusts are expected, but honing in on their location is challenging
at the moment due to a large model spread. Broadly speaking, most
of the Chain will receive high end gales through Friday, with
pockets of storm force winds likely on the backside of the
mesolows.

-CJ

&&

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

The long-term forecast period begins Saturday morning with fair
model agreement depicting a broad upper-level trough stretched
across the Bering Sea into the Gulf of Alaska, creating several
surface low pressure centers in the southeastern Bering and
northern Gulf. These lows will draw westerly gales across the
Aleutian Chain and easterly gales across the northern Gulf coast
into Prince William Sound. Generally a showery, wet pattern will
be in place across all of Southern Alaska, with areas such as the
lower Kuskokwim Valley, and Copper River Basin seeing the driest
conditions. Looking into Sunday model uncertainty remains fair,
with most solutions sinking the low in the Southern Bering across
the Aleutian Chain, into the northern-most Pacific, south of
Adak. By Monday morning, model disagreements become severe with
some solutions keeping a low in the Southern Gulf of Alaska while
keeping coastal Southcentral in a light rain and breezy pattern.
While other solutions take the low southeast, pushing into
Juneau's region before advancing northward towards Southcentral.
By Monday afternoon, models seem to converge on a solution
bringing a strong low pressure system towards the Southcentral
coastline. Heavy rains and strong winds appear to move in, however
timing the system's arrival is still debated. At latest, Tuesday
afternoon will likely be rainy and windy in the Prince William
Sound region. Overall, a wet pattern for the Aleutians and
Southcentral regions, looking colder and drier from mid to late
week for Southwest Alaska, and cooler and wetter for Southcentral.

CL

&&

.AVIATION...

PANC...Gusty southeasterly winds will continue through tonight.
Winds diminish and transition to northerly early Wednesday
morning. Flow aloft may hold on to southeast winds longer after
surface winds have shifted, which may lead to some wind shear
beginning around 12Z Wednesday.

&&