Gale Warning 36, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
508 PM AKST Mon Jan 1 2024

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

A 970 mb low southwest of Kodiak Island and a weak upper level
high over the eastern Alaskan interior maintain easterly flow
over Southcentral Alaska overnight. Light rain and snow showers
will continue along the coast of the eastern Kenai Peninsula.
Lower elevations near the coast might see some mixed rain and
snow, but farther inland and at higher elevations precipitation is
expected to remain as snow. Kodiak will see rain and increasing
winds overnight into Tuesday from a shortwave trough of the low.

After a brief period of weaker winds Tuesday morning, winds up to
gales and increasing rain may be possible in the marine zones
along the northern Gulf coast Tuesday afternoon. Winds will also
increase significantly through the Matanuska River Valley and into
the Palmer and Wasilla areas Tuesday into Wednesday as the
pressure gradient increases and the cold, dense air from the
Copper River Basin flows downslope.

A much larger 940 mb low tracking just south of the Aleutians
will become the dominate system for Tuesday night into Wednesday
as it crosses into Bristol Bay. A foot or more of new snow will
be possible for the passes of the Eastern Kenai with a period of
even higher winds before subsiding Wednesday night. Precipitation
from this system may stretch beyond Thursday as shortwaves
associated with the low continue through Southcentral.

&&

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

An unsettled weather pattern continues from the Central Aleutians
into Southwest Alaska this evening. A 1045 mb surface high
centered over the northern periphery of the Beaufort Sea is
contrasting an approaching sub 950 mb North Pacific low moving
into the Central Aleutians and Eastern Aleutians. A game of where-
are-the-lows is currently being played on satellite. The remnants
of a complex low is slowly dissipating over the western Bering
with multiple smaller lows spinning away to the west of the
Pribilofs. Meanwhile, a cutoff low sits just south of the Alaska
Peninsula with ongoing rain and snow. The main focus, however, is
the approaching sub 950 mb North Pacific low into the Aleutians,
which will bring gusty conditions as well as widespread rain and
snow through the Aleutians and Southwest Alaska over the next
couple of days. Models have been persistent in deepening the low
below 940 mb before it crosses the Eastern Aleutians.

A Winter Storm Warning for the Central Aleutians is valid through
tomorrow evening for expected moderate to heavy snow and winds
gusting as high as 70 mph. Reduced visibility down to 1/2 mile is
anticipated with the heaviest snow totals (up to 8 inches)
forecast over Adak. Further east, a Winter Weather Advisory for
the Kuskokwim Delta Coast comes to an end in the next few hours as
winds have begun to trend down and radar shows snow is in the
process of lifting northward and out of the region. The North
Pacific low has slowed somewhat and is now forecast to eventually
track into the southern Bering by Wednesday morning before
becoming stationary up until dissipation on Thursday. A broad
front will precede the low, tracking from west to east across the
Aleutian Chain and then lifting northward through Bristol Bay and
the Kuskokwim Delta tomorrow night. A High Wind Watch is in effect
for interior Bristol Bay tomorrow evening through Wednesday
morning. While there remains some uncertainty in the strength of
overall winds as the front moves through the region, easterly flow
through the Kamishak Gap could promote winds gusting to as high
as 75 mph from Iliamna down into New Stuyahok and Koliganek. Gusts
to as high as 60 mph will be possible along the Alaska Peninsula,
mainly south of King Salmon, from Egegik to Port Heiden.

&&

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

Active weather continues for the long-term forecast. Confidence is
high that yet another strong low will move into the Bering Sea on
Friday. However, model differences in the the exact low track are
leading to lower forecast confidence for specific impacts. We
will be monitoring the following hazards, with additional hazards
possible but difficult to pin down at this time:

* High Winds: Western and Central Aleutians, Saturday Jan 6
* Heavy Precipitation: Eastern Kenai Peninsula and Prince William
  Sound, Saturday Jan 6 through Sunday Jan 7

Diving into the details, Friday begins with an occluding Bering
Sea low moving into Southwest Alaska, bringing persistent showers
to much of the Southern Alaska coastline. By Friday afternoon, a
strong, 950-960 mb North Pacific low pushes its front into the
Aleutian Islands. The low itself appears to move into the Bering
Sea by Sat afternoon, bringing sustained winds to gale or even
storm force around the Bering Sea and Aleutian Islands. Depending
on the track of the low, the bands of vorticity rotating around
it, and the strength of the cold air advection wrapping around it,
high wind products are not out of the question for Saturday in
the Aleutians.

In addition to high winds, heavy precipitation will also be a
concern. Current thinking is that although precipitation will be
moderate to heavy as the front pushes into the Aleutians, the
front itself will be moving quickly enough to keep precipitation
totals from climbing too high. In fact, Southcentral Alaska, along
the north Gulf coast, will have a higher chance of seeing heavy
precipitation from Saturday through Sunday as the front slows
down due to the low's occlusion. The Aleutian Islands will likely
see rain as 850 mb temperatures climb as high as 2-3 degrees
Celsius, but chances of seeing rain are lower in Southcentral as
cold air wraps back around with the occlusion.

- KC

.AVIATION...

PANC...VFR conditions and light winds will persist through Tuesday
morning. Northerly winds will begin to increase between 18-21Z
Tuesday as pressure gradient increase over the Chugach and Cook
Inlet ahead of an approaching frontal boundary.

PP

&&

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
317 AM AKST Tue Jan 2 2024

AKZ195-030200-
Pribilof Islands-
Including the city of Saint Paul
317 AM AKST Tue Jan 2 2024

...STRONG WINDS DEVELOPING WITH SNOW AND BLOWING SNOW CHANGING TO
RAIN THIS AFTERNOON THROUGH TONIGHT...

A strong low pressure system is poised to move along the Aleutian
Chain today before entering the southern Bering Sea tonight into
Wednesday. Easterly to east-northeasterly winds will pick up
this morning and peak with gusts to 55 mph in the afternoon to
early evening. Winds begin to weaken and turn more northeasterly
during the late evening and overnight hours. The front will reach
the Pribilof Islands this afternoon into the early evening hours.
Precipitation will begin from south to north as the winds are
peaking. There could be enough cold air in place initially that
St. Paul Island could experience a period of snow and blowing snow
late this afternoon into the evening hours before mixing with and
changing over to rain.