Storm Warning 114, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
516 AM AKDT Wed Oct 2 2024

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

Discussion:

Light winds, generally clear skies, and a drier airmass has led to
much of Southcentral seeing low temperatures bottoming out in the
20s to lower 30s this morning with widespread frost. As a result, it
will be a windshield scraping kind of morning for most before
heading off to work. The exception being the Gulf coastal areas
where temperatures are still in the upper 30s to mid 40s. There is
a narrow band of clouds associated with with a weak front lifting
north across the Copper Basin, but this cloud cover has not had
too much of an impact on temperatures. Most of Southcentral will
see near normal temperatures again today and a bit more cloud
cover, but generally quiet weather. A low near Sand Point will
move into the southcentral Gulf by this evening resulting in
scattered showers developing from about Cordova eastwards along
the coast.

Looking into the latter half of the week, a much stronger system
will rapidly approach Southwest Alaska Thursday before slowing as
it moves towards the western AKPen. This system is progged to
deepen into a 950 mb low as it moves into the Bering and with
ridging over the eastern Gulf, a stout pressure gradient will form
over the western Gulf and AKPen by Friday morning. Easterly to
southeasterly cross-barrier flow will increase Thursday leading to
decent downsloping and mostly dry conditions for the western
Kenai, Anchorage Bowl, and Mat Valley Thursday and Friday. The
bulk of the precip will fall over Kodiak Island, the eastern
Kenai, and western Prince William Sound as the front lifts
northward over the Gulf. Should also see east/west gap winds such
as the Turnagain Arm start to increase Thursday with strongest
winds expected Thursday night and into Friday. This system looks
to linger over the eastern Bering through the weekend leading to
unsettled weather through early next week.

- PP

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (Wednesday through Friday)...

MAIN POINTS:

1) A hurricane-force low arrives tomorrow for the Aleutians and
Friday for Southwest Alaska.

2) Multiple high wind watches have been issued for the Aleutian
Islands and are in effect from today through Friday.

3) A special weather statement for high seas and strong winds is
in effect for the Pribilof Islands Thursday morning through Friday
evening.

Current satellite and radar show a trough deepening in the Central
Aleutians with widespread cloudy skies. The potential for fog
exists in the Kuskokwim Delta and Bristol Bay coastline through
the late morning hours before dissipating today. Additionally, a
weak low pressure will bring scattered rain showers to the
Aleutians today with isolated showers for coastal Southwest
Alaska and the Alaska Peninsula.

Models remain in agreement that a robust Bering Sea storm
dropping down from Kamchatka late this evening and traversing the
Bering Sea through week's end. Widespread rain showers through
the Aleutian and Pribilof Islands are expected tomorrow and
Friday. Recent guidance has increased the confidence of a more
northerly track through the Bering Sea starting just east of
Shemya tomorrow morning and reaching just north of the Pribilof
Islands by the evening hours. Additionally, as the low moves
across the Bering, it will deepen from 985 mb to 955mb in the
twelve hours. Hurricane force winds and rain will accompany the
low's movement with the the strongest winds from west-northwest on
the backside of the low. On the northern side of the Aleutians,
wind gusts ranging from 75 mph to 85 mph are possible tomorrow
into Friday afternoon. Wave heights on the northern side of the
Aleutian Chain during the period of highest winds are expected to
range between 30 and 40 feet. Looking ahead to Friday,
southwesterly onshore flow into the coast of Southwest Alaska is
expected with this storm until the front moves onshore Friday
evening.

-DJ

&&

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

The focus in the long-term continues to be a strong storm system
moving from the southeastern Bering late Friday across the AKPen
and into the western Gulf by Sunday morning.

There is high confidence that storm force (55-73 mph) wind gusts
will persist across the eastern half of the Aleutian Chain, as
well as parts of the AKPen, late Friday as the storm system begins
to weaken and drift southeast toward Bristol Bay. As the low
moves south of Kodiak Island Sunday, gusty northwesterly winds
will continue across the eastern Aleutians and AKPen, albeit
slowly trending downward, with widespread gale-force winds and
storm-force gusts Saturday weakening to gale-force gusts by
Sunday.

Farther east, the occluded front associated with the low will
will weaken and become more east-west oriented over Southwest
Alaska by Saturday morning. The strong southeasterly winds
expected Friday will diminish as the front shifts, with winds
becoming more northeasterly on Saturday then northwesterly by
late Sunday. The precipitation along the front will also diminish
from north to south through early Sunday as the northerly wind
flow ushers in cooler and drier air.

The aforementioned occluded front enters the western Gulf late
Friday with rain and strong easterly gales across Kodiak Island.
The front then lifts to the north Gulf coast Saturday morning as
the parent low drifts south across the AKPen. A strong easterly
barrier jet is expected to develop along the coast for Saturday.
The east-southeasterly flow aloft out ahead of the front will also
drive copious amounts of moisture into the coast and over the
coastal mountains. Precipitation will continue into Sunday as
trailing upper-level waves lift south to north across the Gulf in
the wake of the initial front. The track and strength of these
features will dictate where the heaviest precipitation falls.
However, an increase in instability with these waves will bring
about a more convective and showery nature to the precipitation,
potentially leading to waves of moderate to heavy precipitation
along the coast into early next week.

-TM

&&

.AVIATION...

PANC...VFR conditions and light southerly winds are expected to
persist through much of the TAF period. A slight uptick in south
to southeast winds will be possible late this evening into the
overnight as a weak Turnagain Arm wind attempts to develop.
However, if this wind does materialize, gusts this evening into
tonight will likely be only around 15 to 20 kts or less.

&&

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
1254 PM AKDT Wed Oct 2 2024

AKZ195-031600-
Pribilof Islands-
Including the city of Saint Paul
1254 PM AKDT Wed Oct 2 2024

...STRONG WINDS AND HIGH SEAS FOR THE PRIBILOF ISLANDS FROM EARLY
THURSDAY MORNING THROUGH LATE FRIDAY EVENING...

A potent low-pressure system is expected to move across the
central Bering Sea tomorrow morning through Friday morning. Ahead
of the low's arrival tomorrow evening, southeasterly wind gusts
up to 55 mph and steady rain are expected tomorrow. In its wake,
west to northwesterly wind gusts ranging from 55 to 70 mph and
wave heights as high as 20 ft are expected Friday before slowly
diminishing Saturday.