Gale Warning 980, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
540 PM AKST Sat Dec 28 2024

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

Currently, fog is lingering in the Anchorage Bowl. It is forming
over the Knik arm and is advecting into Anchorage by light
northerly winds. The fog is expected to remain through tomorrow
morning as conditions will be quite similar to today with light
northerly winds and generally clear skies. On the other hand, A
Winter Weather Advisory for Thompson Pass remains in effect until
Sunday morning for blowing snow as the pass continues to receive
snowfall and gusty winds. This is being driven by a shortwave and
its associated surface low. The low is pushing winds speeds up in
the Eastern Prince William sound region, especially near gaps and
passes where winds will potentially gust to over 40 mph on Sunday
as pressure and temperature gradients tighten near Valdez. The
surface low is having an effect on winds in the other gap regions
such as Resurrection Bay, Shelikof Strait, Whittier, and other
passes, but the impact is less pronounced. The low is also
generating precipitation in Eastern Prince William Sound and even
the Copper River Basin, where light snow has been falling since
the morning hours in Gulkana. The low will dissipate by Sunday
afternoon allowing wind speeds to lighten and precipitation
chances to diminish.

The cold air mass that has moved in will linger for the rest of
the short term. Temperatures will reach their coldest for
Anchorage, the Mat-Su Valley, and the Kenai Peninsula Sunday as
the core of the Arctic air mass moves north of the region. Highs
will be in the upper teens across the region with colder
temperatures further north. The Copper River Basin will have
temperatures plummet to the negatives, where they will stay for
the short term period.

Changes will take place once again as a large low pushes north
from the southwest. Kodiak Island will receive precipitation
starting Tuesday that will begin as snow but will quickly change
over to rain as the low drags warmer air north. Wind speeds will
begin to increase again in the usual gaps and passes in response
to tightening pressure gradients with the low's approach. However,
for now, it seems that not enough moisture will make it northward
and most areas in Southcentral will remain dry. The exact track
and development is a bit uncertain for this low but the low
appears to stall and begin to elongate south of Kodiak Tuesday
evening.

-JAR

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

The main area of concern over the next 24-48 hours will be over
the Bering, eastern Aleutians, Alaska Peninsula, and western
Alaska coastline as a developing triple-point low from a Kamchatka
low forms in the North Pacific tonight. The triple-point low is
expected to quickly deepen, resulting in a core of storm force
winds around its center as it moves over the eastern Aleutians and
Alaska Peninsula. A High Wind Warning is also out for the
southern AKPEN due to the potential for southeasterly gusts up to
80 mph near Cold Bay and surrounding areas. Unalaska Bay could
experience gusts around 50-60 mph during the morning and afternoon
hours on Sunday as the low enters the eastern Bering.

The core of storm force winds around the low will remain through
Monday afternoon, with the core brushing over the Southwest Alaska
coastline and Pribilof Islands as it moves to the northwest.
Portions of the eastern Bering not covered by the storm force
winds will experience persistent gales through Monday evening
before subsiding to mostly small craft levels. With wind gusts
upwards of 45 mph near the Kuskokwim Delta coast through Monday,
there is an increased potential for periods of blowing snow and
elevated storm surge.

For interior Southwest, conditions will remain mostly calm as a
ridge over most of mainland Alaska keeps the active weather to the
west. The western Aleutians/Bering will experience periods of
rain and snow showers through Tuesday due to the Kamchatka low and
a North Pacific low south of Shemya sending weak fronts over the
area.

-BS

&&

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

The New Year starts with an upper level tilted ridge building
across the Mainland into Siberia by the weekend. This leaves much
of the Interior in a dry and persistently easterly windflow
surface pattern. This extends into an area of gusty winds that
will push across the northern Bering through the period. Further
south, an upper level trough that extends over the Aleutians and
Bering and across the Gulf of Alaska lingers through the forecast
period. The jetstream support for the main cyclone tracks will
also remain well south of the Aleutians and Gulf into Saturday.

Nearly all of the southern coastal portions of the state will
continue with scattered areas of snow, rain and snow mixed or rain
through Thursday. As the surface lows and fronts track eastward
from the south of the Central Aleutians and Alaska Peninsula,
over Kodiak Island to the Southcentral coasts, precipitation areas
will be brief with little to no accumulation. Gusty easterly
winds will occur Wednesday and diminish Thursday across the
Northern Gulf, around Kodiak Island and straddle the AKPEN into
the Eastern Aleutians. Friday brings a low north from the eastern
North Pacific, and spread more moderate snow or rain and snow
from the eastern Kenai Peninsula over Prince William Sound to the
Canadian border. A new system pushing out of Eastern Asia Friday
exerts its influence with more moderate rains over the Aleutians
through Saturday. Gusty winds increase to gale force over the
Western Aleutians Thursday, slowly diminishing and spread all the
way to around Kodiak Island and AKPEN and across the Bering
through Saturday.

&&

.AVIATION...

PANC...Periods of freezing fog and lower visibilities may remain
through early Sunday morning as low level moisture remains with
little wind and cooling temperatures. However, winds are expected
to shift slightly to the east and increase a few knots overnight.
This shift should allow any fog to slide west back over Cook
Inlet and away from the terminal and confidence remains low on how
long and the extent of fog overnight tonight.

&&