Storm Warning 125, NWS Anchorage, AK

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

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

Discussion:

Light winds expected to persist across much of Southcentral,
however skies will begin to fill tonight as a new weak low
pressure system approaches the north Gulf Coast. This should keep
temperatures Thursday morning from dipping as cold as they did the
previous few mornings. The aforementioned new low pressure system
is currently located southeast of Kodiak island and will move
into the northern Gulf this evening resulting in scattered showers
developing from about Cordova eastwards along the coast. This
system is expected to be supported later by a following stronger
system in the Bering Sea that will push a relatively stronger
front into the Gulf of Alaska by Friday. This pattern may maintain
the wet pattern across the Gulf Coast into the weekend, with
interior Southcentral appearing mostly dry, but more cloudy.

The front in question is associated with a strong Bering Sea low,
which appears to remain anchored over the Bering into the weekend.
On the eastern side of the Alaska Peninsula, the front will push
across Kodiak Island by late Thursday night into Friday morning,
leading to a relatively quick shot of rainfall and southeasterly
winds. By Friday morning, the front will be pushing into the
northern Gulf of Alaska, moving into Prince William Sound and
reinforcing the ongoing precipitation. The direction of the wind
flow given this pattern does suggest that inland areas such as
Anchorage and Western Kenai would be mostly downsloped, but
periods of rain are possible beginning Friday afternoon. This
appears to be a fairly resilient system, with the trough expected
to linger in the northern Gulf into the weekend, maintaining the
precipitation across the Gulf coast. Areas such as Thompson Pass
may see periods of snowfall with this system given the cold air in
place and the incoming moisture. While confidence on snow
accumulation totals is low, drivers through the area should be
prepared for the potential for some wet snow on the roadway
during the cooler parts of the day.

-CL

&&

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

MAIN POINTS:

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

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

3) A special weather statement is in effect for the Pribilof
Islands Thursday morning through Friday evening.

4) A high surf advisory has been issued for the Kuskokwim Delta
and is in effect from Thursday morning through Friday morning.

There is high confidence and model agreement that a hurricane-
force low from Kamchatka is traversing the Bering Sea and will
bring widespread impacts to the Aleutian Chain and coastal
Southwest Alaska through week's end. The low is moving from the
Western Aleutians tonight to just north of the Pribilof Islands
by Thursday night, deepening from 970 mb to 951 mb as it moves
across the Bering. From here, the low will start to weaken and
stall out as it makes landfall with the Kuskokwim Delta. 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.

-DJ/TK

&&

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

The focus in the long-term continues to be a strong storm system
moving across the AKPen and into the western Gulf Sunday morning.
As the low tracks south of Kodiak Island on Sunday morning,
northwesterly winds for the eastern Aleutians and AKPen will
decrease to less than gale-force strength with possible gale-force
gusts persisting through Sunday afternoon. Rainfall chances for
the AKPen and southwest Alaska diminish by Monday morning as
northerly wind flow ushers in cooler and drier air. Ridging builds
over the western Aleutians by Tuesday morning and extends into
the AKPen by Wednesday morning, as the next system emerging off of
the Kamchatka Peninsula enters the western Bering Wednesday
afternoon.

Trailing upper level waves behind the initial front associated
with this system will continue to keep the northern Gulf coast
gusty with strong east-southeasterly flow. Ample moisture within
the onshore flow will allow for heavy rainfall throughout Sunday
into Monday for the coast and coastal mountains, with decreasing
rainfall amounts by Monday night. Given the orientation of the
flow, the greatest precipitation totals are expected for the
eastern Kenai Peninsula and Prince William Sound. Precipitation
should diminish by Tuesday morning as weak high pressure builds
over Southcentral Alaska by Wednesday afternoon.

-JH

&&

.AVIATION...

PANC...VFR conditions and light 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. Ceilings
may lower to around 5,000 ft Thursday morning as a frontal system
approaches.

&&