Gale Warning 893, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
427 PM AKST Sun Dec 29 2024

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

Currently, upper level ridging is taking place over much of
Alaska. As a result, mostly clear skies and calm winds are
prevalent in much of Southcentral. Gusty winds through gaps and
passes are also subsiding some as temperature and pressure
gradients loosen. Fog has mostly cleared out across the region,
but there is still some lingering in the Copper River Basin and
parts of the Cook Inlet. Conditions will begin to change tonight
as our next low approaches from the south. A upper level wave will
pass through tonight and will increase cloud cover and slightly
increase wind speeds. This will greatly diminish chances for fog
tonight. However, conditions won't be too dissimilar to last night
to completely end chances for fog, with decent temperature
inversions present especially in the Copper River Basin.

The aforementioned wave ahead of the approaching low will bring
plentiful moisture and increase chances for precipitation mostly
in Kodiak, but also the Kenai Mountains and the southern Alaska
range west of the Cook Inlet. Kodiak City may briefly receive
snowfall before warm air advection causes temperatures to increase
above freezing. Wind speeds will turn southeasterly and gradually
increase to gale force in the waters around Kodiak Island
including Shelikof Strait, Kamishak Bay, and the Barren Islands.
In contrast, the inland areas of Southcentral, are expected to
remain dry and relatively calm. As the low gets closer by Tuesday
evening, the closed high to the northeast between the Yukon and
Eastern Alaska will influence its track. The low will take a turn
to the west and pass south of Kodiak Island. This will orient
winds in such a way that storm force winds will be possible in
Shelikof Strait.

As the low moves west, it will leave a parting gift in the form of
an inverted trough that will move up the Gulf on Wednesday.
Widespread precipitation along the coast is expected with this
trough. Temperatures will be cold enough along the coast, that
light snowfall is possible. Another effect of the through is small
craft wind and near gale force winds along the Southcentral
coast. Inland areas will miss out once again on both the
precipitation and winds. As the inverted trough quickly moves out,
wind speed and precipitation chances will slowly diminish by
Wednesday afternoon.

-JAR

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

Strong winds continue across the eastern and northern Bering
tonight as a strong low pressure system continues to drive
northwestward. Gusts up to 65 mph are still possible along the
Pribilof Islands tonight, with gusts of 45 to 60 mph possible
along the southwest Alaska coastline. With the front of the low
moving over the coast tonight, brief periods of a rain/snow mix
are also possible. Strong southeasterly flow aloft will result in
upslope precipitation along the southern Alaska Peninsula and
Ahklun Mountains through early Tuesday. A broad area of low
pressure will reside in the North Pacific beginning Monday
afternoon and lasting through Wednesday. The exact positioning of
the low by midweek is uncertain, with the only concern being the
placement of rain and snow over the Alaska Peninsula and eastern
Aleutians.

For interior Southwest, conditions will remain mostly calm as a
ridge over most of mainland Alaska continues to keep the active
weather to the west. The western Aleutians/Bering will experience
periods of rain and snow showers through Wednesday due to the
multiple lows surrounding the area.

-BS

&&

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

A broad upper level ridge extending from the Western Canadian
Provinces across Mainland Alaska and continuing into the Russian
Arctic through most of the forecast period. The ridge is briefly
interrupted by an upper level Arctic trough slipping over the
Yukon Territory on Friday, and re-establishes itself Saturday.
Widespread dry and colder conditions prevail over most of the
Alaska Interior. The cold outflow brings some gusty winds into the
Northern Bering that will merge with another system from the
Southwest Friday. An equally elongated trough stretches from
Eastern Asia over the Aleutians and Bering into the Gulf of
Alaska, supporting a series of surface lows and fronts through the
weekend. Jetstream support of the storm tracks remains well South
of the Aleutians through the forecast period. Blended ECMWF/GFS
and Canadian models carry the features through Sunday.

A weakening low center South of the Alaska Peninsula spreads
rain, changing to snow further inland into the AKPEN, Kodiak
Island and along the Kenai Peninsula into Prince William Sound,
diminishing through Saturday. A well developed low and front bring
more moderate rain and gale force winds into the Western
Aleutians Thursday, and spreads over the Aleutians and Bering as
the low tracks East. Gale force winds push across the Central and
Eastern Aleutians for Friday, diminishing late Saturday as the
gales move into the Western Bering but maintaining gusty winds up
to gale force all the way over to the Gulf by Sunday. With the
associated front closing in on the AKPEN and Kodiak Island, areas
of heavy rain develop along the Pacific side from the Shumagin
Island to the mouth of Prince William Sound by Sunday.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. The biggest
question in weather around the terminal will be redevelopment of
fog/low stratus around the area. A bank of low stratus expanded
out of Turnagain Arm along the mountains earlier this morning, as
well as around upper Knik Arm near Birchwood AP. Overall,
conditions look to stay mostly the same in the low atmosphere so
patchy stratus and fog will remain around the area, but not
expected to be widespread.

MTL

&&