Small Craft Advisory 939, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
519 AM AKDT Tue Oct 22 2024

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

A low continues to sit over the Chukchi Sea this morning with a
ridge downstream across the northern British Columbia. Predominant
flow is out of the west to southwest across much or the Bering
Sea and across the southern half of the mainland. A strong cold
front is moving through the eastern half of Southcentral Alaska
this morning. A burst of snow has started for Glennallen, while
Valdez and Thompson Pass are starting to see improvements from
snow and lowered visibility in blowing snow last night. Some
clearing skies and continued strong wind are expected behind the
front. Gusty west to southwest winds is expected across much of
the Gulf, as well as Kachemak Bay and up the Cook Inlet into the
western Kenai Peninsula and greater Anchorage area. Winds could
begin to diminish later tonight as the winds shift more westerly.
Gusty gap winds will likely continue for Whittier through midweek.

Lingering showers in upslope flow along terrain is becoming more
scattered to isolated across the area this morning with the
exception of a band continuing to bring precipitation between
Wasilla and Houston. Near Talkeetna, where freezing rain occurred
yesterday, has low stratus and developing fog nearby. Multiple
weak short waves over the next couple of days will bring periods
of additional precipitation across parts of the Alaska Range,
Chugach and Talkeetna mountains. Light snow accumulations may
develop northeast of Palmer toward Eureka through Wednesday
morning, as well as along the Richardson Highway Wednesday
morning. While the general idea of cooling temperatures and
quieter weather pattern is on track with some confidence, there
are still some differences in the specific details. This feature
may also produce a few flurries for lower elevations from
Anchorage north and east, with some lingering and potentially
accumulating snow for higher elevations.

Precipitation die off by the afternoon and the next low arrives
to the western Gulf from the eastern Bering later Thursday
afternoon. Where Kodiak was being downsloped by westerly winds, a
front will shift the pattern completely, bringing rain and
southeast winds to the Island for Thursday through Friday. The
front lifts north later on Thursday, spreading precipitation
across the northern Gulf coast and Prince William Sound. The
surface low could remain far enough south to keep most of the
precipitation closer to the Gulf/Prince William Sound coastlines
and northerly offshore flow for much of Southcentral.

rux

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (TODAY THROUGH THURSDAY...)

The broad-scale pattern over the past few days has been dominated
by a robust low pressure system in the Chukchi Sea. Influence from
this low will begin to degrade today, and diminishing
southwesterly onshore wind flow will lead to lowering water levels
along the Kuskokwim Delta and western Bristol Bay by tonight.
A Coastal Flood Warning remains in effect for the Kuskokwim Delta
and a Coastal Flood Advisory for the western Bristol Bay along
with a Special Weather Statement for areas along the Kuskokwim
River through late this evening. Following this pattern, a mostly
zonal west-to-east wind flow pattern will establish across the
Bering, with a slight disturbance entering the western Bering by
Wednesday morning.

This disturbance will deepen rapidly as it moves east into the
Southeastern Bering Sea, becoming a low pressure system and
bottoming out in the eastern Bering by Wednesday night. By
Thursday morning, a corridor of strong storm-force northerly
winds are expected to develop along the western, backside of the
low, pulling cold air out of the north allowing for gusty
conditions as well. Near midnight Wednesday into Thursday, the
Pribilof island are expected to see the periphery of this
corridor, potentially seeing northerly winds of up to 50 mph over
the islands. Later Thursday morning, the core of strong winds is
expected to shift over Unimak Island, bringing elevated winds to
areas such as Cold Bay and False Pass, as well as through Unimak
Pass and out of the southern gaps and passes of the Alaska
Peninsula. These strong winds show the potential to persist into
late Thursday afternoon, but by Thursday night, should weaken and
shift out of the area to the south.

CL

&&

.LONG TERM FORECAST (THURSDAY TO NEXT MONDAY)...

Confidence is increasing that a deepening low in Bristol Bay
Thursday moves over the AKPen and into the North Pacific through
the day. During its southeastward progression, southwest winds
and increasing wave heights are likely along the northern AKPen
and portions of the Southwest AK coastlines. Elsewhere, high
pressure in the North Pacific south of Adak will progress
southeastward Thursday as a front from a Kamchatka Low moves
through the Aleutians Saturday reaching the Southwest coastline
late this weekend/early next week.

A low crossing into the North Pacific deepens as it progresses
into the Gulf of Alaska this weekend. During its southeastward
travel through the Gulf, increasing winds through Shelikof
Strait, Kodiak Island and the Kenai Peninsula can be expected.
Additionally, confidence decreases this weekend with the
placement of this low in the Gulf however, there are indications
that it will begin to strengthen early in the weekend. As the low
strengthens, the possibility of increased gap winds returns for
Price William Sound.

DJ

&&
.AVIATION...

PANC...VFR ceiling and visibility persist. Southerly winds of 20
kt gusting to 30 kt will be possible through Tuesday afternoon...

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
1238 PM AKDT Tue Oct 22 2024

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

1130 AM     Coastal Flood    Kipnuk                  59.92N 164.10W
10/22/2024                   Bethel             AK   Local Official

            High water in Kipnuk limited to lowland
            flooding and water in yards and across
            fields and tundra.

&&