Gale Warning 121, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
550 AM AKST Tue Jan 28 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
3/Today through Thursday Night)...

The longwave upper-level trough sits anchored over the western
half of the state this morning. Multiple shortwaves and vorticity
maxima continue to rotate around this trough, moving from
southwest to northeast over Southcentral from the AKPen and
Western Gulf.

Two such waves can be seen on satellite this morning. The first is
driving toward the Copper River Delta, bringing snow to the
central and eastern Chugach Mountains as well as to Valdez and
Cordova. The second is a weaker feature moving up northern Cook
Inlet. This feature is spinning up a meso-low at the surface,
lifting over the Talkeetna Mountains and bringing snow to the
mountains and along the Glenn Highway northeast of Palmer and
Sutton.

As the aforementioned features lift north, another wave will slide
east from Bristol Bay to Cook Inlet. This feature will help to
usher in another wave of arctic air and allow for additional snow
shower activity from Kenai north to the Mat-Su Valleys later
today. One challenge with this feature is that yet another wave
will drop in from the northwest tonight as the entire upper-level
low moves toward Southcentral. Models are hinting at the
development of a second meso-low over Cook Inlet, dropping south
from Anchorage to Homer overnight. If this comes to fruition,
locations along the western Kenai Peninsula could see a brief
bout of snow and blowing snow before the system moves over the
Barren Islands.

As each of these features rotates and lifts northeast, periods of
light snow will be possible over the Copper River Basin.
Accumulations are expected to be light; however, any snow could
linger into Wednesday.

As the wave potentially spinning up the Cook Inlet meso-low moves
into the Gulf for Wednesday, the westerly flow aloft and strong
cold air advection will allow for a rapid increase in gap winds,
especially for places like Seward and Whittier. The upper-level
flow then becomes a bit more northerly by late Wednesday and into
Thursday as the upper-level low moves over the Talkeetnas and
eventually into the northeasterly Gulf. Gap winds will increase
for Broad Pass and Isabel Pass by late Wednesday morning with
strong winds developing for Thompson Pass and Valdez for Wednesday
afternoon. Considering that these passes all received quite a bit
of snow from our big storm event last weekend, it is likely that
blowing snow will be a concern as the winds resuspend snow that
has already fallen. Visibilities north of Paxson and in Thompson
Pass could even drop to a quarter mile of less at times in strong
winds.

In addition to strong winds through gaps and passes, expect strong
winds across the coastal water along with falling temperatures.
The result will be the development of widespread freezing spray
beginning Tuesday night and Wednesday. Heavy freezing spray is
likely along the Alaska Peninsula from southern Cook Inlet through
Shelikof Strait.

Finally, temperature will continue to fall through Thursday, with
almost every locations below zero by Thursday morning. For areas
still dealing with winds, winds chills could fall to 25 to 40
below zero for interior locations and mountain passes.

&&

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

Key Messages:

 - A Cold Weather Advisory is in effect for the Kuskokwim Delta
   beginning tonight and continuing through Thursday morning for
   wind chills as low as 40 to 50 below zero.

 - Periods of strong winds and blowing snow are expected through
   this evening for the Eastern Aleutians and Southern Alaska
   Peninsula. Gusty northwesterly winds combined with snow showers
   could significantly reduce visibilities.

Satellite this morning shows much of the southwest mainland
Alaska sky clearing out. Areas of upslope-driven low stratus and
light snow showers remain for areas on the windward side of the
Kuskokwim and Alaska Range Mountains as westerly to southwesterly
upper level flow continues to establish the very cold airmass over
Southwest Alaska. Elsewhere, gusty winds and snow showers
associated with a compact low that traversed over the Pribilof
Islands overnight continues to move southward towards the Eastern
Aleutians and Southern Alaska Peninsula. Gale-force winds with
gusts up to 50 mph along with snow showers are expected to
continue through this evening for the Eastern Aleutians and
Southern AKPen. Conditions will improve from west to east
throughout the day as the low continues southeastward into the
North Pacific.

Temperatures this morning continue to plummet across Southwest
Alaska with many areas already in the minus teens. Beginning
tonight, the Kuskokwim Delta and Lower Kuskokwim Valley will see
temperatures fall to near -20F with windchills reaching -40F.
Daytime temperatures for Wednesday for these areas will remain
well below zero, before further falling to -20F to -30F with wind
chills between -40F to -50F Wednesday night into Thursday morning.
Bristol Bay will be "warmer" with low temperatures reaching the
minus teens Tuesday night/Wednesday night. The Alaska Peninsula
will be the "warmest" with temperatures from -4F to 18F between
Pilot Point and False Pass respectively. Daytime temperatures will
be subzero for all areas except from Pilot Point south on
Wednesday.

The next weather driver will be an incoming front set to
move over the Western Aleutians this morning. A band of gale
force winds surrounded by widespread small craft will move west to
east across the Bering Sea through the end of the week.
Precipitation will move along the front, starting as snow
initially and transitioning to rain as warm air encroaches in. The
Western/Central Aleutians will likely see very little, if any,
snowfall due to already having temperatures at or above freezing
prior to precipitation. The front reaches the Pribilof Islands by
tomorrow morning, bringing rounds of snowfall and gale force
winds. There is potential for blowing snow conditions as the
arrival of the front precedes the warmer air by several hours
before transitioning to a rain/snow mix and then rain. Similar
conditions are expected along the Kuskokwim Delta Coast by
Thursday.

-JH/KM

&&

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

Seasonably cool temperatures continue over much of the
southeastern half of the State as the longwave trough over the
Bering Sea retreats back towards the Arctic and the building high
pressure ridge shifts towards the East. Several shortwave troughs
with associated surface lows will move through the Gulf of Alaska
through the end of the week producing moderate coastal rain and
mountain snow to Prince William Sound and into the Copper River
Basin. Cooler air across the Interior to the Kenai Peninsula,
Kodiak Island, Anchorage and Mat- Su Valleys will start to warm as
more southerly winds return to the area early next week.
Precipitation during this time is favor a rain/snow mix later
transitioning to more rain at the lower elevations at the start of
the new week.

A building pressure gradient will produce strong southerly winds
across the Central Aleutians through the Western Alaskan Peninsula
and Southern Bering Sea through the end of the forecast period.

-DD

&&

.AVIATION...

PANC...VFR conditions should persist through the TAF period.
There is a chance a some flurries or very light snow showers this
afternoon into the evening as a weak upper disturbance lifts over
the area. A lower cloud deck could form as a result of snow shower
activity, but VFR should be maintained. Gusty south-southwesterly
up-inlet winds will begin to diminish by late this morning or
early afternoon and turn northerly by this evening. A few gusts
between 15 to 20 kts are possible Wednesday as a reinforcing shot
of cold air works in by then.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
929 AM AKST Tue Jan 28 2025

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

0916 AM     Snow             6 SE Valdez             61.11N 146.22W
01/28/2025  M2.5 Inch        Chugach            AK   CO-OP Observer

            0.27 SWE.

&&