Storm Warning 132, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
542 AM AKDT Thu Oct 10 2024

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

A surface low in the northern Gulf in conjunction with a short
wave has sent rain and snow showers over the Anchorage area and
eastward through Prince William Sound overnight into early this
morning. This low will dissipate throughout the day with shower
activity decreasing. However, this break in the weather will be
short lived as a strong storm, currently in the Bearing Sea, is
headed this way.
This is an interesting storm with the way it is expected to
develop as it moves toward the Gulf of Alaska. Right now, one can
see the jet stream flowing south of the low as it spins in the
Bearing Sea. This will cause a triple-point low to develop and
move northward along the front tonight. What is unusual is the
strength of this secondary low as the main low looks like it wants to
become a complex low. The initial front will cross Kodiak Friday
and continue to head to the north Gulf coast and bring in very
strong winds to that region as well. This whole storm system is a
bit chaotic and is unusually difficult to nail down when and where
the heaviest rain and strongest winds will be.

It does look like the main impacts will be very strong winds in
Kodiak (with a high wind watch for Friday) and the along the
northern Gulf to southern Cook Inlet for Friday. There coastal
regions will also see periods of heavy rain tomorrow.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (Today through Sunday morning)...

The low pressure system in the Bering Sea continues to deepen and
move eastward. The center of the low currently sits north of the
Central Aleutians, where they have started to see an increase in
winds and scattered light precipitation. Further east, a band of
clear skies ahead of our Bering low will allow for radiative
cooling early this morning in Southwest Alaska, bringing morning
temperatures down to the low 20's for select locations, especially
in the interior.

For the rest of today, the low center will slide to just
southwest of the Pribilof Islands. A ridge building over Kamchatka
is aiding in some northerly cold air advection getting wrapped
into the low, enhancing the winds on the backside of the storm.
The Western and Central Aleutians look to see sustained gale-force
to storm-force winds for most of today. The low tracks southeast
across the Alaska Peninsula (AKPEN) tonight and into Friday
morning, where a triple point occurs. It meanders here for the day
before moving more towards Western Gulf late Saturday.

With this, the High Wind Watch for the Eastern Aleutians has been
upgraded to a High Wind Warning which is in effect Friday morning
through early Saturday evening. The High Wind Watch for the AKPEN,
specifically for locations west of Nelson Lagoon, remains out
from Friday morning through Saturday afternoon. Both the Eastern
Aleutians and west of Nelson Lagoon on the AKPEN will see 50 to
60 mph north winds with the possibility of gusts up to 75 mph.
The best chance to see hurricane-force gusts will be through
channeled terrain. Due to a long and persistent northerly fetch,
seas 20 to 25 ft are expected in Outer Unalaska Bay and marine
zones north of the Eastern Aleutians.

For Bristol Bay and the rest of Southwest Alaska, we can expect
strong easterly to northeasterly winds Friday and into Saturday.
Winds through Kamishak Gap could reach 50-60 mph and affect
nearby communities. A Special Weather Statement remains issued to
address the gusty Kamishak Gap winds over Greater Bristol Bay.
Overall, this should be a relatively dry system with light
precipitation in Bristol Bay. The greatest rainfall amounts look
to occur across the Pribilof Islands with the initial front today.
Heavy rain is also likely across the North Pacific side of the
AKPEN with southerly upslope flow associated with the main Bering
front Thursday, but also into Friday as the new triple- point low
spins up. Elsewhere to the north, persistent northerly winds and
cool temperatures are expected for the Kuskokwim Delta through the
weekend.

&&

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

By Sunday, the broad low encompassing most of southern Alaska is
likely to have weakened to gale force. A broad swath of gales
will extend across the eastern Bering Sea as cold, Arctic air
streaming southward leads to an unstable atmosphere that will
allow stronger winds aloft to mix down to the surface easily. This
will keep gusty winds blowing across the Pribilof Islands,
eastern Aleutians, and Alaska Peninsula through Monday. Seas,
initially 15-20 ft on Sunday between the Pribilof Islands and the
eastern Aleutians and in portions of the Gulf of Alaska gradually
subside heading into Monday. Precipitation will largely be focused
along the coast of the Gulf of Alaska, as moist, unstable air
rotates up from the North Pacific and is squeezed out along the
coastal mountains in the form of rain showers. There will also be
snow showers across the eastern Bering Sea, eastern Aleutians, and
Alaska Peninsula as the cold, Arctic air surges across the
relatively warm waters of the Bering Sea. Inland precipitation
will be limited by cross-barrier flow and a lack of strong forcing
aloft, though a weakening front may extend into Southwest Alaska
from the Interior on Sunday, which could produce a band of light
snow. All of these precipitation features weaken on Monday as the
parent low weakens over the Gulf and shifts slowly east.

High pressure over the western Bering on Sunday will gradually
work into the northern and eastern Bering and leading to dry
conditions over Southwest Alaska for Monday and Tuesday. For the
Aleutians, conditions will primarily be dictated by the
extratropical remnants of Tropical Storm Barijat (formerly 21W).
The low will center near Kamchatka on Sunday, pushing its front
into the western Aleutians. As the low tracks eastward, its front
will progress to the eastern Aleutians by Wednesday. Southeasterly
winds along the front may reach gale force at times as weak
shortwaves lifting along the front enhance instability and tighten
the pressure gradient. Along the front, precipitation will fall as
rain as the result of warmer tropical air entrained in the
remnants of Barijat. Finally, a chance of light snow occurs for
inland areas of mainland Alaska as a strong shortwave trough
drops south from the Chukchi Sea on Wednesday and brings even
colder air aloft.

Quesada

&&

.AVIATION...

PANC...MVFR to IFR ceilings and visibility are expected through
23:00Z, improving to VFR. Periods of rain/snow mix with up to 1/2
inch of accumulation unpaved surfaces.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
1038 AM AKDT Thu Oct 10 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0525 AM     Snow             1 NNE Anchorage (Potter 61.06N 149.76W
10/10/2024  M1.5 Inch        Anchorage          AK   NWS Employee

            Still snowing at time of measurement.

&&

PP

Preliminary Local Storm Report
National Weather Service Anchorage AK
1236 PM AKDT Thu Oct 10 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0730 AM     Snow             Northeast Anchorage     61.21N 149.76W
10/10/2024  M0.7 Inch        Anchorage          AK   NWS Employee

            An NWS employee measured 0.7 inches of snow.

0912 AM     Snow             Rabbit Creek            61.07N 149.77W
10/10/2024  M1.0 Inch        Anchorage          AK   Trained Spotter

            A trained spotter measured 1 inch of snow
            overnight. Precipitation changed to rain by
            report time.

&&