Gale Warning 37, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
457 AM AKST Tue Jan 2 2024

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

The low southwest of Kodiak has rapidly weakened as expected and
can hardly be seen on satellite early this morning. The front
that extended out of this low is moving northward over the Gulf of
Alaska and it did spin up a closed low along it which was a
question from yesterday. This low is much more prominent on
satellite in the central Gulf than its parent low and is
producing Gale force winds along much of the Gulf coast. This low
will also rapidly weaken over the course of the day, but not
before bringing rain to the eastern Kenai Peninsula with light
snow inland over the Kenai Mountains. Kodiak will stay in the rain
and wind as this front moves through this morning and then the
next, stronger, front moves into the area by this evening. This
second front is associated with a very large and still
strengthening low just south of the central Aleutians this
morning. This low will stall out in the eastern Bering Sea for
most of the remainder of the week and keep mild, southeasterly
flow moving into Southcentral Alaska the rest of the week.

This pattern will increase the northeasterly winds out of the
Matanuska River Valley today and likely bring in wind gusts from
35 to 50 mph into the Palmer and Wasilla areas late tonight
through Wednesday. There may be some areas of blowing and
drifting snow with these winds.

A strong front associated with this Aleutian low will move across
Kodiak tonight and then weaken some as it moves to the north Gulf
coast Wednesday. There will be a mix of rain and snow with this
front for the Kenai Peninsula and north Gulf coast on Wednesday.
Upslope areas on the windward side of the mountains will see the
vast majority of the precipitation with inland areas on the lee
side of the mountains downsloping out. By Wednesday night, some
colder air aloft will trickle into the area due to the occluding
low and should begin to shift the dominant precipitation type back
to snow for most of the area.

&&

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

The forecast is largely on track with a large, strong, deep low
moving towards the Aleutian Chain. The models are all showing this
system dropping to around 937 mb this morning. The front attached
to this behemoth moves over the Central and Eastern Aleutians this
morning, and then tracks up the Alaska Peninsula towards the
Southwest coast through this afternoon. Storm force winds and high
end gales are approaching the Aleutians currently. Adak's latest
observation at 4am had a peak wind gust of 53 mph and Dutch Harbor
at 47 mph. Strong winds will continue pushing northward along the
southern Alaska Peninsula today. Colder air will hold on over the
Central Aleutians this morning, keeping precipitation all snow.
The Winter Storm Warning for the area remains in effect.
Temperatures should rise by this afternoon, allowing snow to
transition to a rain/snow mix or all rain. Additionally, winds for
this area will come down below storm force, but will remain in
higher end gales.

Reverting the discussion back to winds: the High Wind Watch
remains in effect for Bristol Bay. Overall, warning level winds
are NOT expected for most areas, however, wind gusts reaching 60
mph are possible, namely along the Alaska Peninsula south of King
Salmon, as well as along the higher elevations. BUT! Areas
particularly vulnerable to the strong easterly winds racing out of
Kamishak Gap may see warning criteria wind gusts to 75 mph, this
includes Iliamna, Koliganek, and New Stuyahok.

Moving further along the coast, the Winter Storm Watch has been
upgraded to a Blizzard Warning for the Kuskokwim Delta coast and
Nunivak Island tonight. Wind gusts to 50 mph are possible and
areas of blowing snow will bring visibilities down to a quarter
mile at times with snow accumulations between 1 to 3 inches
possible.

Lastly, not wanting to leave the Pribilof's out of all this
wintertime fun, they too will see high end winds with gusts to 55
mph possible this afternoon into this evening. Winds switch to
northeasterly overnight and will begin to weaken. There is a
chance for snow and blowing snow so long as the cold air holds in
place this evening.

&&

.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 will persist. Low level wind shear is
expected to develop this morning as surface winds will be
northerly with winds aloft increasing to southeast 25 to 30 kt at
the 2000 ft level. These winds aloft may increase more than
current 30 kt so that is something to watch as the day goes on.

&&

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.

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

AKZ112-030130-
Matanuska Valley-
Including the cities of Palmer, Wasilla, Sutton, and Chickaloon
403 AM AKST Tue Jan 2 2024

...STRONG GUSTY WINDS AND LOCALIZED AREAS OF BLOWING AND DRIFTING
SNOW THIS MORNING THROUGH WEDNESDAY...

Northeast winds will steadily strengthen across the Matanuska
Valley today and then peak late tonight into Wednesday afternoon.
Wind gusts are expected to reach 40 to 50 mph late tonight and
Wednesday before starting to diminish some Wednesday night.

While the recent cold and dry weather has lessened the amount of
transportable snow by forming a crust on top of it, the winds
will be strong enough to produce localized areas of blowing and
drifting snow. Expect some areas where snow drifts cause difficult
driving conditions.