Gale Warning 770, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
527 AM AKST Tue Dec 26 2023

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

A deep and cold upper level low pressure system located over the
Bering Strait will remain in place today and Wednesday and then
begins to retreat to the north. A weak ridge builds into the
southern Bering Sea on Thursday and Friday and into the northwest
Gulf of Alaska and mainland Alaska for Friday into Saturday. A
blocking ridge builds northward over Western Canada and into the
Yukon Friday into the Weekend.

On the surface a weak but cold high pressure system remains parked
over Western Alaska with well below normal temperatures found
over the Bering Sea and Southwest Alaska. A weak low pressure
system currently near Cold Bay will continue to push north and
east into the the Northwestern Gulf of Alaska today passing over
Kodiak Island as a 994 mb low this afternoon and will dissipate
over Prince William Sound tonight. As the low pushes north expect
isolated to scattered snow showers to develop this afternoon over
the Western Kenai Peninsula, Cook Inlet, the Anchorage Bowl as
well as the Matanuska and Susitna Valleys where 1 to 2 inches of
accumulation is possible as the low moves north and weakens. The
snow showers will be accompanied with strong and gusty winds and
may briefly reduce visibility in blowing snow as the showers pass.
Snow showers will be likely this afternoon and evening as well as
overnight over the Eastern Kenai Peninsula and Prince William
Sound, where 2 to 4 inches of snow accumulation are expected.
Scattered snow showers are also expected to develop late this
afternoon and evening and continue over night in the Copper River
Basin.

Locations that managed to clear out overnight have dropped into
the single digits above and below zero this morning. High
temperatures today will struggle to reach into the teens over much
of the inland areas today and 20s near the coast. Temperatures
tonight will be highly dependent on cloud cover with inland
temperatures dropping again to the single digits below to the
single digits above. Locations in the Copper River Basin that
clear out will likely drop into the teens below. Low temperatures
along the coast will drop into the teens and low 20s. Winds in
Inland areas will again be light and variable today and tonight
except in and near stronger snow showers while coastal locations
will be gusty with outflow winds.

&&

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

Multiple upper level and surface features will bring active
weather to Bristol Bay over the next 24 to 36 hours. The main
features this morning are an upper level shortwave and its
attendant surface low over the Alaska Peninsula, and a stout
shortwave rounding the base of the deep upper low over the
northern Bering. These features are merging over Bristol Bay, and
will generate an area of snow along the northern coast of Bristol
Bay, where an advisory is now in effect till Wednesday morning. A
meso-low near the surface is generating gusty north winds around
Dillingham and Manokotak. This, in combination with falling snow
is will continue to lower visibility through the morning. Light to
moderate snow will continue through the day, with the higher
accumulations expected to be around the Dillingham area. These
features will spread inland this afternoon, bringing a couple
inches to interior Southwest. Increased cloud cover will also help
to alleviate the very cold temperatures in the Lower Kuskokwim
Valley this morning.

Overnight the upper low will consolidate and move into the
Interior. To its south, a narrow band of ocean effect snow
showers are expected to train somewhere between Togiak and
Dillingham. Should these showers continue over one area, expect
snow accumulations up to or over a foot. Snowfall rates in these
showers could reach 1-2 inches per hour. Influence of the trough
will wane Thursday, with patchy showers and light winds over
Southwest and the Alaska Peninsula.

Over the Bering today cold temperatures will persist with
scattered to numerous snow showers. A few polar lows are
embedded on a shortwave moving east near the Pribilofs this
morning. One of these features hit the Islands and created a
brief period of intense winds and heavy snow. Otherwise, showers
and 15 to 30 kt westerlies will continue through Wednesday
afternoon when a moderate to strong front reaches the western
Aleutians. This feature will spread into the Bering through
Friday, bringing a mix of rain and snow along the occluded front
and gale to storm force winds.

-Jones

&&

.LONG TERM FORECAST (Days 4 through 7: Thursday through New Years
Day)...

The weather pattern starting this Thursday and lasting through
Monday, New Years Day, is seemingly dominated by some form of a
Bering Low pressure system. Shortwaves will rotate around the
base of this low. Weak troughing across the Gulf will give way to
weak ridging for a few days. But by next weekend, that ridging
will slide east across the panhandle. This will give way to
continued southerly flow for much of south central. The early week
cold temperatures will bring warming with no significantly
impactful weather systems moving towards southcentral. For the
Bering and Southwest, the first of two systems will move from the
central Aleutians Sunday/Monday before weakening over the Akpen
Monday. The second of two systems is progged to develop and deepen
across the western Aleutians near New Years Day. Despite being a
week out, models and ensembles are in good agreement in having a
very strong low move towards the central Aleutians and Bering.
Early indications are of a sub 960mb low and strong storm force
winds, though in time, that will easily increase... as it is
something to watch for as the week progresses.

&&

.AVIATION...

PANC...While conditions stayed mostly clear overnight, fog is
finally starting to build in north and east Anchorage early this
morning, with hints of low stratus near the terminal on satellite.
Current thinking is that IFR/LIFR vis and ceilings will move over
the terminal very soon, then linger through about noon.
Conditions expected to improve to VFR around noon, then snow
chances increase by evening as a weak low moves through Anchorage.
High confidence that any snow that falls will be light. Moderate
to high confidence that easterly winds aloft will also pick up
this evening, leading to wind shear.

-KC

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
1119 AM AKST Tue Dec 26 2023

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

0828 AM     Snow             Rabbit Creek            61.07N 149.77W
12/26/2023  M0.4 inch        Anchorage          AK   Trained Spotter

            A trained spotter measured 0.4 inches of
            snow overnight. Not snowing at observation.

&&