Gale Warning 27, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
430 PM AKST Tue Jan 7 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Friday night)...

Currently, conditions are calming down as the remnants of the
strong low that impacted the region continue to dissipate.
Precipitation continues to decrease and has mostly stopped in the
Anchorage Bowl and the Mat-Su Valley. Precipitation lingers in
Prince William Sound and the mountainous regions of the coast as
well as further inland. Gusty winds are also diminishing due to
less substantial pressure rises and pressure gradients than we
were seeing this morning. Parts of the Copper River Basin near
Gulkana Airport were seeing incredible gusts of over 70 mph in
the early morning. These winds have calmed down to near 20 - 25
mph at the time this was typed. Temperatures have warmed all
across southwest with them being above freezing almost everywhere
in the lower elevations. This is due to the warm air advection
that the low brought up into the region, as well as the gusty
winds that have mixed warmer air from above. The overall air mass
will remain similar over the next couple of days with some slight
cooling due to calmer winds and cooler air wrapping in from the
west. Winds will reach a minimum on Wednesday, but a weak
shortwave will keep precipitation chances elevated for the coastal
and mountainous regions before the next system impacts the
region.

As mentioned before, a new low will track up the Gulf of Alaska
starting Wednesday afternoon and its effects will start to be felt
soon afterwards. Wind speeds in the Gulf will start increasing
through Wednesday night and will reach a maximum early Thursday
morning. Storm force winds are expected in a line south of the
coast and through prominent gap regions such as the Barren
Islands, Kamishak Bay, and Shelikof Strait. Kodiak Island will
also feel near storm force winds along its eastern and southern
coasts. This low will be quite the soaker as heavy precipitation
will first impact Kodiak Island and then all along the coastal
regions of Southcentral. Unlike the previous low, this low will
track further to the east, meaning lower precipitation chances for
the Anchorage, Mat-Su Valley, and the Western Kenai Peninsula
regions. Warm air advection will accompany this low, albeit a bit
less so than the prior low, so small snow accumulations may be
possible in mid level elevations (500 to 1000 ft) and further
inland areas of the mainland before the main core of warm air
arrives on Thursday afternoon. Once the warmer air arrives, mixed
precipitation could become an issue once again especially for the
Valdez/Thompson Pass region. Winds won't be nearly as strong for
the mainland with this low as it appears to weaken before it moves
onshore. Still, the Matanuska Valley, Turnagain Arm, and the
usual small gap regions could see gusty winds.

After this messy pattern, A weak ridge will begin to move into
the Gulf Friday morning, allowing for a brief respite from active
weather. It wont be long before another low begins to enter the
Gulf from the west at the end of the forecast period on Friday
afternoon. The exact track and strength of the low is uncertain as
of now, so exact impacts are not currently known. However, one
can expect more precipitation and winds in the near future.

-JAR

&&

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

As a relatively weak low pressure system continues to spin about
in the Central Bering, a front spread across coastal Southwest
this afternoon will shift steadily inland as it breaks down and
loses support. The front is driving largely rain showers now
across the northern Bristol Bay coastline and into interior
Bristol Bay. The aforementioned low in the Bering will continue to
spread snow showers across the Western and Central Aleutians
tonight, lifting by Wednesday morning as the low continues to
weaken and shift steadily northward, eventually out of the area.

Wednesday morning are expected to be mostly benign with most of
the major weather makers yet to move in. Later Wednesday
afternoon however, a pair of low pressure systems will be
approaching the southern coast of Alaska, one heading into the
western Gulf of Alaska, the other approaching the western/central
Aleutian Chain. The former will approach first, spreading a swath
of rain and a rain/snow mix to the Alaska Peninsula. Strong winds,
potentially reaching up to Storm Force through Shelikof Strait,
in the marine areas northeast of Chignik. Offshore flow will
initiate across Bristol Bay, with gusts up to 30 mph possible near
Dillingham Thursday morning. A deformation band may form on the
northern side of the low, increasing the likelihood for
precipitation in the Greater Bristol Bay area, which may initially
fall as snow late Wednesday night/early Thursday morning but warm
and transition to a rain/snow mix or plain rain at times.
Precipitation from this system is expected to persist into late
Thursday night.

The latter system, approaching the western/central Aleutians from
the southwest, will begin bringing rainfall to the Aleutians,
centered initially about Adak Island, and spreading a front
quickly eastward, reaching Unalaska by Thursday afternoon, and the
Alaska Peninsula by Friday morning. Southerly flow from this
system will keep Southwest Alaska relatively warm, keeping
precipitation associated with this system as rainfall.

-CL

&&

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

A very active weather pattern will continue for much of southern
Alaska through the weekend into early next week. The longwave
pattern features a strong upper level low dominating much of the
Bering Sea and western mainland Alaska and a steep ridge of high
pressure along the Canadian Coast and Eastern Alaska. On Saturday,
heavy precipitation along the Southcentral coast continues as a
shortwave trough and associated surface low push inland.

By Saturday night, confidence is moderate to high on a strong
North Pacific low and its associated front traversing northward
across the Alaskan Peninsula into Bristol Bay and Southwest
Alaska. This pattern will bring unseasonable warmer temperatures
and mixed precipitation along the coastlines near the surface and
has the potential for heavy snow accumulations in the higher
elevations. Strong winds will also accompany this system across
Kodiak Island, the Alaska Peninsula, and the Bristol Bay and
Southcentral Alaska coastlines, although timing and intensity will
still depend on the the exact low track, where there is still
minor uncertainty. A new surface low may form off the Kenai
Peninsula early Monday morning, continuing and potentially
enhancing winds and precipitation along the coast through early
Monday afternoon.

-ME

&&

.AVIATION...

PANC...Southerly up-inlet winds will likely transition to
Turnagain winds through tomorrow morning while slowly weakening. A
few more showers may move over the Terminal today but conditions
will likely remain VFR.

&&