Gale Warning 879, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
442 AM AKST Tue Dec 17 2024

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

A narrow ridge is in place from British Columbia northwest to the
Y-K Delta while a broad trough with multiple embedded shortwaves
exists to the south and west. The combination of these features
are keeping most areas dry with slightly above normal
temperatures. Meanwhile the Seward area and Kodiak Island are
getting light upslope precipitation. Radar indicates most of the
precipitation is in the Seward area this morning, but it may move
north into Whittier/Portage this afternoon as the ridge moves
slightly to the north. The light precipitation will taper off
through Wednesday morning as a low over the southern Panhandle
cuts off moisture and another shortwave ridge builds in over the
Gulf. This will lead to the sunniest of the days for much of the
region, allowing temperatures to drop a few degrees.

Looking ahead into Thursday and Friday, a series of increasingly
strong and wet systems will begin to chip away at the ridge over
the mainland. The system on Thursday is expected to move south of
or over the southern edge of Kodiak Island, bringing rain to
Kodiak and the Gulf/Sound areas along with upper elevation snow.
The exact track of the low is poorly resolved, but the net effect
for the precipitation forecast is the same. The wind forecast on
the other hand, particularly for marine areas, remains poorly
resolved. Most of the forecast guidance has this system
dissipating or becoming an inverted trough as it enters Bristol
Bay, leaving behind upslope precipitation for the eastern Kenai
Peninsula and Kodiak Island. Precipitation from this system may be
heavy at times. For Friday, a very strong and wet system is
expected to move into the Gulf. This system may have widespread
wind and heavy precipitation (mostly rain) for Southcentral by
Saturday. Stay tuned for updates.

-CJ

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3)...

The majority of Southwest Alaska and the Aleutians are under broad
low pressure with multiple systems spreading from the western
Bering Sea to the North Pacific. The combination of an upper low
currently centered just south of the eastern Aleutians and a
Southcentral ridge nudging in is promoting predominantly
southeasterly flow over the region. Widespread gale-force winds
and shower activity are prevalent across the eastern Bering and
Alaska Peninsula (AKPen). A series of compact surface lows will be
taking turns swinging north across the Aleutians/AKPen into the
Bering Sea over the next couple days. These will be the main
weather drivers as they track generally north and west near the
Pribilof Islands and out to the western Bering. Southeasterly flow
will continue to bring light to moderate rain to the south-facing
slopes of the Aleutian Mountains.

The first low will pass over the Shumigan Islands this morning,
bringing a local enhancement of wind and precipitation. A wave
with some upper level support will push the next round of weather
to the southern AKPen/eastern Aleutians early Wednesday morning,
where gusts over 50 mph are possible for higher elevations and
areas around Cold Bay.

By Thursday morning, a stronger low from the North Pacific looks
to swing north into the western Gulf, bringing the potential for
sustained storm force, northeasterly winds out of Shelikof Strait
with gales spreading to around Chirikof Island. Precipitation in
the models appear to rain out a lot of moisture before pushing
over the Aleutian Mountains into Southwest Alaska, but it is
looking likely that some of that moisture could spill into
Bristol Bay region.

Rux/TK

&&

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

An unsettled weather pattern continues as a large trough,
situated between the Aleutian Islands and the Gulf of Alaska,
draws-in multiple low pressure systems from the North Pacific
across the Gulf of Alaska. Model consensus has improved on a
compact low crossing the southern edge of the Western Gulf and
passing south of Kodiak Island Friday afternoon. This will be
followed by a shortwave on Saturday afternoon, and a second low
entering the Gulf Sunday afternoon.

Rain will be enhanced by terrain at low elevations and mountain
snows possible for coastal regions, while downsloping should
reduce the amount of precipitation that reaches inland locations.
This pattern is expected to persist through the weekend, with the
strongest winds coming from the east, affecting areas which
include the Barren Islands, Kodiak Island, and Eastern Kenai
Peninsula.

&&

.AVIATION...

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

&&