Gale Warning 290, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
340 AM AKDT Sun Apr 16 2023

.ANALYSIS AND UPPER LEVELS...

The overall pattern across the region remains amplified with a
ridge of high pressure building over the Bering and a low
pressure located in the Gulf. Waves of energy are noticed on radar
producing light snow showers along the Prince William Sound coast
early this morning while higher-level clouds are being pushed
inland. Looking closer at the low in the Gulf of Alaska, multiple
centers can be seen with the largest one in the northwestern Gulf
near Kodiak Island. This low is expected to remain complex with
multiple centers as is slowly weakens. Out west, clearer skies are
being observed on Nighttime Microphysics Satellite Imagery as
high presure builds overhead. Snow showers are also being observed
along the Alaska Peninsula as northerly flow tracks over the
eastern Bering.

&&

.MODEL DISCUSSION...

Overall, models are in fairly good agreement with synoptic scale
features through at least mid-week. However, models are continuing
to struggle with the finer details regarding the complex low
located in the Gulf, but this should have relatively low impact
on sensible weather for higher population areas, with expected
impacts remaining across the offshore marine areas.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist.

&&

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

Several low pressure systems will rotate around the Gulf of
Alaska bringing precipitation to Kodiak Island and the eastern
Kenai Peninsula today. The most significant low is moving south
this morning and will produce light snow from Whittier south to
Seward and Kodiak Island with only minor snowfall accumulations
expected. This low will move south of the area this evening with
precipitation ending. For the rest of Southcentral an upper level
trough over western Alaska will bring in cooler air today and into
Monday with temperatures near or below normal for mid April.
Otherwise expect a mix of snow and clouds today for inland
portions of Southcentral Alaska. On Monday a weak shortwave will
move out of the Gulf and bring the threat of a few showers on the
hillsides across the area, but most populated locations are
expected to be mostly dry. As we head into Tuesday temperatures
will begin to warm into the low to mid 40s as an upper level
ridge builds across Southcentral this should keep most of the area
dry with mostly sunny conditions.

&&

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

Overall quieter weather pattern sets up over Southwest Alaska with
a building ridge taking over the Mainland. There were some areas
of blowing/drifting snow along the Kuskokwim Delta yesterday
during peak winds, with similar possibilities today. Dry
conditions are expected across Southwest over the next few days
and temperatures are to remain below normal. Daytime temperatures
today and tomorrow will hover in the mid-20's for the lower
Kuskokwim Valley and Bristol Bay, and mid-teens in the Kuskokwim
Delta, and overnight temperatures dropping into the single digits.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2: Today
through Monday)...

Cold air continues to filter across the eastern Bering Sea and
southern Alaska Peninsula, allowing for elevated winds,
especially through gaps and passes south of the AKPen through
today. Winds should begin to slowly diminish overnight Sunday into
Monday. Higher winds south of Kodiak Island and out of Wide Bay
may continue into Tuesday morning. Active weather approaches the
Western Aleutians on Monday. A front extends off a system moving
over the Kamchatka Peninsula Monday afternoon and then weakens as
it begins to push against the ridge in the central Bering.
Anticipate gale force winds and periods of rainfall through the
early week across the Western Aleutians and western Bering Sea.

&&

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

Looking into the extended forecast, the Southern mainland looks to
stay mostly quiet throughout the long-term as high pressure looks
to build in from the north and west. There may be some weak waves
progressing through the flow that could offer up the chance at
very light precipitation for interior Southcentral Alaska through
Friday. Then agreement and confidence decreases on the evolution
of a potentially stronger wave dropping southward from an upper-
level polar low on Saturday. Depending on how this wave evolves
will determine how much precipitation will be enhanced. As of now,
the most favorable locations to receive precipitation from this
wave would be interior locations of the Susitna Valley and
northern portions of the Copper River Basin.

Out west, guidance is in loose agreement on mainland southwest
Alaska remaining mostly quiet and benign through the long-term.
Ridging builds in from the north and flow becomes offshore in the
upper levels from northeast-to-southwest through the day
Wednesday. The same story of relatively quiet and benign weather
is also true for the Alaska Peninsula and the eastern
Aleutians/Bering Sea. However, the western/central Bering and
western/central Aleutians will remain relatively active through
the long-term as multiple low pressure systems, coupled with
gale-force fronts, will impact those areas. The first system will
be a potential gale-force front pushing eastward from the western
Aleutians to the central Aleutians Wednesday and Thursday. This
front will weaken on Thursday as it bumps up against a ridge in
the eastern Bering. The next system that is reasonably agreed
upon, arrives to the western Aleutians and Bering for Saturday.
This again, will mostly be an eastward moving front emanating
from a Kamchatka low pressure system.

&&

 $$

SYNOPSIS AND MODEL DISCUSSION...NSC
SOUTHCENTRAL ALASKA...RC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KM
LONG TERM...DAN