Gale Warning 66, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
435 PM AKST Thu Jan 11 2024

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

The blocking pattern remains in place today as a large arctic
airmass over Canada begins to surge south into the lower 48. An
amplified ridge has moved over Alaska, extending down through the
Gulf and into the far eastern Pacific. With the blocking pattern in
place, a series of lows will be forced to ride up the western
side of the ridge...gradually damping out the ridge before it
finally translates eastward this weekend.

Middleton Island Radar imagery shows showery activity has
blossomed across the northern Gulf of Alaska today in response
rather strong cold air advection overhead, yielding low-level
lapse rates in excess of 7.5 C/km. Light precipitation has made it
inland as far as Turnagain Pass and Girdwood. Snow totals through
tonight will be on the light side with a couple inches of snow
possible in the higher elevations.

Further south, the system lifting north across the AK Peninsula
continues to bring strong wind and rainfall to Kodiak Island. The
front associated with the system will continue to lift north
through the Kenai Peninsula tonight. Between the warm advection
with the front and cold air from the east, a strengthening
baroclinic/frontal zone will yield an increase in wind speed over
the Gulf through tonight. Storm-force (48kt) will continue near
Kodiak Island and through the Barren Islands tonight before
subsiding tomorrow.

This first system will quickly weaken as the surface low moves
towards the southern AKPen, but another system right on its heels
will allow for another wave of precipitation for Kodiak and the
eastern Kenai for Saturday. Easterly flow should keep the western
side of the Kenai, the Anchorage Bowl, and north into the Mat-Su
Valley generally dry through downsloping until the system pivots
and flow becomes more southerly later this weekend.

With cold air entrenched in the Copper Basin and approaching low to
the south, the resultant gradient will allow for gap flow winds in
all the usual spots through tomorrow.

-Brown/PP

&&

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

It has been an active weather week across the Bering and
Southwest Alaska. Currently, an occluded low north of the Pribilof
Islands this evening is finally moving out of the region. Across
Southwest, southerly flow ahead of a near-stationary front will
continue to promote a warming trend through Saturday morning. A
North Pacific low tracking along the AKPEN is transitioning to an
open wave. This wave will move across Southwest Alaska on Friday
as a trough. Light scattered showers will be possible with the
trough's passage, though the bulk of precipitation will likely be
confined over the mountains. Easterly winds remain elevated across
the Greater Bristol Bay area, specifically out of the Kamishak
Gap into Koliganek and New Stuyahok. Gusts approaching 70 mph will
remain possible through Koliganek. Winds across New Stuyahok have
diminished to around 60 mph. Overall winds will weaken more
substantially early Friday morning as the pressure gradient
finally relaxes across the region.

An active pattern will also continue the next few days across the
Aleutian Chain. A second occluded low is pushing across the
Western Aleutians this evening. Its front is approaching the
Eastern Aleutians, which will also bring renewed shower activity
for Friday. More notably, a North Pacific low is forecast to lift
northward across the Eastern Aleutians late Friday into Saturday.
Cold air already in place across the Bering, a result of northerly
flow behind the low currently moving through the Aleutians, will
be drawn further southward and wrap into the North Pacific low.
This, along with strong height rises behind the low, is expected
to promote intense northerly winds on the backside of the low.
Northerly winds will increase from west to east, with Nikolski to
feel the initial brunt of winds. Elevated winds should then
expand eastward through Saturday morning, with winds finally
tapering of from west to east across Akutan. A high wind watch for
winds gusting up to 75 mph is in effect from 10pm Friday through
noon Saturday AKST.

Saturday into Sunday will see a broad wind field spread across
the Bering and into Southwest Alaska, as the North Pacific low
occludes. Cooler temperatures will move into Southwest Alaska on
Sunday, bringing the unseasonable warming trend to an end.

-BL

&&

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

An upper level ridge extends across the Bering through the
forecast period. A series of weak lows stream across from the
Russian Chukchi Coast and Arctic to develop a deepening trough
along the Alaska-Canada Border. A surface front riding over the
Bering portion of the ridge brings gusty winds with areas of gale
force gusts from the Western Aleutians into Western Alaska,
diminishing early Tuesday. Gusty Easterly winds remain South of
the Aleutians through Thursday. Moderate outflow winds develop
across Southcentral Alaska after midweek.

Kutz

&&

.AVIATION...

PANC...VFR conditions and light northerly winds will persist. High
clouds should prevent fog and/or stratus development tomorrow,
but it remains a low end possibility.

&&