Gale Warning 157, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
520 AM AKST Mon Feb 5 2024

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

Today's system is currently lifting towards the southern Kenai
Peninsula this morning with the back edge beginning to clear out of
southern Kodiak Island. Kodiak has been reporting a mix of rain and
snow overnight through early this morning as surface temperatures
hover a few degrees above freezing, and will likely see this mix or
a complete changeover to rain before the system clears the island by
mid to late morning. Precipitation will spread north into the
southern Kenai and temperatures should warm enough in the lower
elevations to see a rain/snow mix changing over to rain. Colder
temperatures further north will keep precipitation all snow as the
system lifts inland later today.

The system responsible for today's precipitation is currently
spinning over the Bering Sea with frontal boundary and associated
trough lifting north across the AKPen and the western Gulf. Models
once again have a surface low developing just off of Kodiak Island
by 18Z. The low will move up along the eastern Kenai before quickly
moving off to the east. Easterly winds will increase over the
western Gulf as the low deepens, and with modest cross-barrier flow
developing...the western Kenai and Anchorage Bowl will see
downsloping set-up. This should keep much of the western Kenai up
through the Matanuska Valley on the drier side for much of the day.
May see a few passing snow showers, but more steady light snow
doesn't look promising until cross-barrier flow relaxes as winds
become more northeasterly as the surface low moves east into the
Gulf later today. The eastern side of the Kenai and western Prince
William Sound areas will see the bulk of the precipitation with
several inches of snow possible for Seward and Whittier seeing
accumulations of around 5 to 7 inches. Behind this system we will
see quiet weather and near normal temperatures returning for much of
Southcentral.

- PP

&&

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

Key Points:

* Winter Weather Advisories are in effect for parts of Kuskokwim
  Delta and Bristol Bay today. Blowing snow will reduce
  visibilities to one-half mile or less at times.

* A strong storm moving in on Tuesday could bring gusts to 70 mph
  for the Eastern Aleutians and Southwest Alaska. We're monitoring
  the potential for a High Wind Watch or Warning if there is a
  good chance that gusts will reach 75 mph or greater.

Discussion:

While major updates were made to Tuesday's forecast, today's
forecast remains mostly on track. An occluded low currently
lingers in the Bering Sea near Adak, while its front extends
across the Northern Bering and Southwest Alaska. Radar shows snow
steadily moving northward across Kuskokwim Delta and Bristol Bay,
with visibilities beginning to drop due to falling and blowing
snow. A Winter Weather Advisory is in effect for the Kuskokwim
Delta coast/Nunivak Island and Bristol Bay (north and west of
Dillingham) for today. The forecast looks on track for this
advisory, though we've trended towards precipitation tapering off
a bit more quickly. This could lead to conditions improving a earlier
than what's currently listed in the advisory, which is something
we'll be monitoring through today.

For the Bering Sea and Aleutians, expect snow/rain showers and for
strong winds to gradually diminish through today. The latest
observations show maximum gusts of 50-65 mph for Adak, Atka, and
Nikolski. Winds should peak by mid-morning, so it's unlikely that
we'll see gusts much stronger than what's currently being
observed. The other thing to note for the marine forecast is a
slight chance for thunderstorms/lightning near the Eastern
Aleutians and Alaska Peninsula as convective clouds move in ahead
of the next storm. Lightning observed with this system has been
sporadic, so while a few more bolts aren't out of the question,
there shouldn't be any widespread lightning.

Speaking of the next storm, winds and precipitation chances also
increase along the Eastern Aleutians/Alaska Peninsula by late
this afternoon as a strong North Pacific low moves in. The biggest
overnight update with the forecast has been to dramatically
increase wind speeds associated with this low. Model agreement had
been very poor regarding this feature the past few days, but
forecast confidence has been steadily improving. Confidence is
high that the strongest sustained winds will be at storm force (>=
50 kt), but there is lower confidence regarding the placement of
the strongest winds and the strength of the strongest gusts. Once
again, we'll be examining the potential for winds to meet or
exceed 75 mph (which is our High Wind criteria). Areas that could
see high winds include the Eastern Aleutians, Alaska Peninsula,
Western Capes of Bristol Bay, and Kuskokwim Delta. Southerly flow
and warm air advection will also lead to some question about
precipitation type. Overall, lots of questions remain with the
forecast for Tuesday's storm. Please stay tuned as we continue to
refine the forecast.

- KC

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

A weakening upper-level low centered over Chukotka extends a
trough axis across the Alaska Peninsula and into the Gulf which
passes over Southcentral Thursday. This feature is expected to
bring gale force winds across the Bering and measurable snowfall
across Southern Alaska. An active pattern continues Friday morning
when a North Pacific low south of Kodiak Island progresses north,
pushing gale force wind across the Gulf, and bringing snow to the
northern Gulf coast through Saturday afternoon. This is followed
by several upper level shortwaves extending from a low complex
over the eastern Bering, which pass over Southwest and
Southcentral through Sunday afternoon.

&&

.AVIATION...

PANC...

Chance for low stratus this morning but mostly VFR conditions
today into tonight. There is a front moving in that will bring
some snow to the area, however, there is a high likelihood that
Anchorage will remain downsloped and dry. Cloud ceilings may drop
to MVFR late tonight.

&&