Gale Warning 724, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
456 PM AKST Thu Nov 23 2023

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

There is a closed upper low over the Central Aleutians that will
continue to kick shortwave energy into Southcentral Alaska. Expect
more moisture advection and more southerly flow. Cold air has been
slow to scour out in multiple locations, meanwhile rain has been
observed at Homer, Kenai and Anchorage. The models are in good
agreement with the synoptic pattern but there are model
differences in the short term forecast period regarding the
timing and progression of this series of shortwaves. By Sunday
that upper level low will be south of Cold Bay and all the while
kicking more shortwaves into Southcentral. Honing in on the timing
of precipitation and precipitation types will remain challenging.
With the longwave trough in place, expect a persistent pattern.
Things are lining up for an interesting El Nino at the high
latitudes.

&&

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

A weakening low near Nikolski continues to bring wet and windy
conditions to the Bering Sea/Aleutian Islands and precipitation-
type concerns to Southwest Alaska. From Friday through Sunday
afternoon, a front moving west to east across the Bering Sea
brings a shift towards more dynamic and active weather.

Where do we stand with regards to the freezing rain forecast? The
Winter Weather Advisory for Lower/Middle Kuskokwim Valley has been
extended through noon on Friday. As of the writing of this
discussion, temperatures in Sleetmute have topped out at 28
degrees. With daylight fading, it looks like surface temperatures
will remain below freezing until the afternoon tomorrow.
Meanwhile, the sensor at Sparrevohn (elevation 484 feet) shows
observed temperatures climbing into the mid-40s today, confirming
that temperatures aloft are certainly above freezing. As weak
upper level shortwaves rotate around the low and into Southwest
Alaska, any precipitation that falls will likely do so as freezing
rain. Freezing rain could remain in the forecast for Lower
Kuskokwim Valley through Saturday morning as forecast high
temperatures hover just around freezing. At the same time, today's
high of 28 in Sleetmute signals that surface temperatures are
very close to reaching the freezing point; if it does so tomorrow,
we could see a transition towards plain rain/snow by the
afternoon.

Further west in the Kuskokwim Delta, surface high temperatures
have largely risen above freezing. However, with minimum
temperatures potentially dipping below freezing at the surface
and temperatures aloft remaining above freezing, have kept a
slight chance of freezing rain in the forecast through tonight.

Otherwise, the next big weather maker is on the way as a Kamchatka
low pushes its front across the Bering Sea, reaching the Western
Alaska coast by Sunday afternoon. Confidence is high that this
will be a gale force front, with localized areas of embedded storm
force winds. The minor challenge with this front will be
identifying where triple point lows develop along the occluding
front, as these developing lows will lead to increased winds in
their immediate vicinity. Otherwise, model agreement is good with
this front, leading to relatively high forecast confidence from
Friday evening through Sunday afternoon.

-KC

&&

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

The workweek opens with a well developed upper level low exiting
the Russian Far East into the Northern Bering. Its long wave
trough rotates across the Aleutians and Bering into the Mainland
and Gulf of Alaska by the end of the period. Several short waves
will ripple through the flow over the Aleutians, bringing periods
of heavier precipitation and gusty winds. This pattern will
displace the warmer temperatures over most of the state as the
trough moves across the Southern half of Alaska by Thursday.
Strong winds are expected as this system progresses Eastward. Some
gale force winds spread over the Aleutians and Bering for Sunday,
but diminish as the main trough approaches the Alaska Peninsula
by Tuesday. A closed low develops South of Dutch Harbor on Monday,
but its stronger winds will not come to bear until the low moves
towards the Alaska Peninsula. Gale force gap winds are expected
over the Alaska Peninsula and around Kodiak Island for Wednesday
before diminishing Thursday over the Gulf. Locally heavy
precipitation will occur along the North Gulf Coast and move into
Southeast Alaska by Thursday. A strong trough brings gale force
winds to the Western Aleutians and Bering for Wednesday and
Thursday.

Kutz

&&

.AVIATION...

PANC...Temperatures are expected to remain above freezing at the
airport through the night tonight and the day Friday. therefore
any precipitation should be in the form of rain. There is a chance
for some MVFR ceilings at times this evening into Friday with the
mostly likely time period this evening and overnight. Winds
should remain mainly from the north through Friday.

&&