Gale Warning 145, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 PM AKST Wed Jan 31 2024

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

A very cold Arctic airmass is settling into place across Southcentral
as an upper-level trough digs south. Highs around or below zero
and lows well below zero are expected to continue for much of the
area outside of immediate coastal locations along the PWS and Gulf
of Alaska. Many inland areas may not see daytime temperatures
rise above the negative teens until Saturday or Sunday. Although,
as northerly winds continue to increase into tonight, gaps winds
will be gusty and this will allow typical gap locations (such as
Seward, Whittier, Valdez) to remain above zero. Any clouds or fog
formation of Cook Inlet fog/low stratus could moderate temperatures
a bit. The Susitna Valley and Copper River Basin look to see the
coldest temperatures with readings dropping to 30 to 40 below by
Friday morning. The Copper River Basin will hold onto the cold air
Saturday morning with temperatures once again dropping to near 40
below. With surface high in place, winds will remain light in the
Copper River Basin. Winds are expected to be especially strong
and gusty through Thompson Pass, where a Wind Chill Advisory
remains in effect through noon on Saturday. Strong northeasterly
winds gusting to 50 mph will combine with very cold air
temperatures to produce wind chills a low as 55 below zero.
Blowing snow will reduce visibility to one half mile or less at
times. Winds are generally expected to start diminishing by late
Friday into Saturday.

&&

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

The low that brought a round of snow and blowing snow to the
Kuskokwim Delta this morning has since dissipated after moving
inland, leaving behind scattered cloud cover and noticeably
warmer temperatures across the northern half of Southwest. Farther
south, a stalled front is beginning to push light snow into the
western fringes of Bristol Bay, and this pocket of light snow is
set to shift east into King Salmon and Iliamna overnight tonight.
Across the Bering Sea, an upper level ridge is starting to build
into place overhead. At the surface, a stalled/warm front is
slowly crawling north through the Pribilofs ahead of a North
Pacific low currently south of Adak making quick progress towards
the southern Bering. This front will continue to focus gusty
easterly winds over mainly St Paul as light snow continues
overnight, where a Winter Weather Advisory remains in effect.

Going farther out from Thursday onwards, the overall pattern will
become more and more active with time as multiple strong lows ride
north from the base of a deepening trough over the western Bering
and the ridge slowly shifting from the eastern Bering into
Southwest. The first system will cross into the Bering near
Amchitka overnight tonight or early Thursday morning, pushing a
strong gale force front with snow changing over to rain along the
central and eastern Aleutians throughout the day on Thursday.
At the same time and farther north, a core of storm force winds
will develop between the low pivoting west across the western
Bering and Arctic high pressure still entrenched closer to the
Bering Strait. Extreme freezing spray rates are likely to develop
with the very strong east winds along the ice edge Thursday and
Thursday night, mainly in the general vicinity of St Matthew. The
low's front will reach Southwest by Thursday night, but will begin
to slow and weaken on approach. Overall potential for snow and
blowing snow as this front stalls out offshore looks relatively
low, except along the immediate coastline from Thursday night to
early Friday. Meanwhile, another low will push a low-end storm
force front into the western and central Aleutians as it
approaches from the south on Friday, with yet another push of snow
changing over to mainly rain. The front will continue to push
northeast towards the Pribilofs and southern AKpen through
Saturday as the parent low slowly lifts over the western Bering.
Widespread snow and blowing snow are likely to spread across much
of Southwest as the front approaches on Saturday, with several
inches of accumulation possible.

-AS

&&

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

A series of weak upper level lows stretch from the Russian Far
East across Northern Alaska into the Northern Canadian Provinces
through the period. A number of short waves with moderate
amplitude track through the pattern, bringing periods of active
weather across the region. Forecast models are clustering well
with the medium to large scale features, and this composite
reduces the uncertainty through Wednesday. Dry Arctic air
continues its spread over most of Interior Alaska into the Bering,
driving gusty Easterly winds approaching gale force across the
Northern Bering. Relatively warm, moist air rides over a North
Pacific ridge across Southern Alaska. Local areas of gale force
winds over the Western Aleutians diminish in areal size and
overall strength as each trough moves Eastward. Precipitation
starts as snow and changes to a rain-snow mix and then all rain
over the Eastern Aleutians, Alaska Peninsula and Kodiak Island.
Gusty Northwesterly winds move across the Shumagin Island Monday,
and Southeasterly gap winds approaching gale force move over the
Barren Islands late Monday into Tuesday. A gusty Easterly barrier
jet forms along the North Gulf Coast Tuesday, diminishing Wednesday.
Rain and snow mixed or rain will spread over the coastal portions
and Prince William Sound through the end of the forecast. Inland
areas remain under periods of snow.

Kutz

&&

.AVIATION...

PANC...Fog is the primary forecast challenge over the terminal
for the next few days with mainly clear skies, light winds and a
strong inversion. The environment is extremely favorable for the
formation of fog, and if fog does form timing its arrival and
dissipation will be difficult. We will continue to monitor trends
and current conditions and will update the TAF accordingly.

&&