Gale Warning 815, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
508 PM AKST Fri Dec 15 2023

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

Snowfall in the Anchorage area will move off to the east this
evening and continue across the northern Gulf toward the panhandle
coast. Snow over Prince William Sound and the Copper River Basin
will wind down overnight. Skies should clear behind this feature;
however, lingering low stratus is possible across Cook Inlet
through Saturday morning.

Attention then turns back to the west as a storm force low sweeps
a front from Kodiak Saturday morning to the Southcentral coast by
Sunday morning. Strong wind gusts are likely both along the coast
and through gaps as the pressure gradients tightens. Heavy
precipitation is also likely along the coast with ample moisture
advecting over the Gulf with east-southeast winds. The challenge
will be determining if locations along the coast will see enough
of a warm-up to change snow over to rain by Sunday morning.
A foot or more of snow is possible from Thompson Pass to
Turnagain Pass if enough cold air remains in place. Locations in
the lee of the mountains will likely see little precipitation due
to downsloping. Southerly winds and a brief warm up is likely from
Kenai to Palmer as the front lifts north by midday Sunday.
However, this system will be quickly occluded with colder air
wrapping back in. So any brief warm up with southerly winds should
come to an end as wins diminish and colder air returns by Sunday
evening.

Models show multiple shortwaves lingering through the weekend,
clearing the Kenai Peninsula and the Anchorage area by Monday
morning, with precipitation continuing for the Prince William
Sound. The NAM alone maintains precipitation over the northern
Kenai, Anchorage, and Mat-Su, regions through Tuesday.

&&

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

Active weather looks to continue through the short-term period.
across mainland Southwest, the Bering Sea, and the Aleutians.
Light snow is now arriving to the Kuskokwim Delta Coast this
evening as the tail end of a shortwave clips the area. The rest
of Southwest remains quiet through tonight. A low pressure
currently developing over the Central Aleutians gathers strength
tonight. This low and its front track to the Southwest coast, in
the vicinity of Bristol and Kuskokwim Bays, by Saturday morning.
With the combination of cold air in place, a tight pressure
gradient, and strong off-shore winds, a Blizzard Warning has been
issued for areas west of Dillingham tomorrow morning through noon
time. Conditions should improve during the afternoon as winds
begin to diminish and temperatures warm. A Winter Weather Advisory
for snow and blowing snow has been issued for the Kuskokwim Delta
Saturday morning into the evening hours. Lower visibilities could
be prolonged into Sunday for Nunivak Island due to persistent
strong northwest flow on the backside of the low discussed
previously, as well as with additional shortwaves dropping
southward through the flow. Snow and blowing snow is also possible
for the southern Alaska Peninsula (AKPEN) Saturday morning behind
the low. More snow is possible on Sunday for the Southern AKPEN
with strong cold air advection and support from the upper levels.
Sunday stays unsettled for mainland Southwest with more shortwaves
coming ashore from the Bering helping to keep snow showers going,
especially over the Kuskokwim Delta and Lower Kuskokwim Valley.
Meanwhile, snow showers continue for the Bering and Aleutian Chain
through Sunday. A strong front enters the Western Bering Sunday
and moves to the Southern AKPEN by Monday evening. Rain and snow
will accompany the front as it moves west to east, with and
rain/snow mix transitioning back to snow behind the front as cold
air works back in. Stay tuned for forecast updates as the active
pattern continues!

&&

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

A broad upper level longwave trough extends across the Bering
into Western Interior Alaska through Wednesday. After midweek, a
strong shortwave reorients the longwave trough with greater
amplitude over Western Alaska into the weekend. However,
significant shortwaves will continue to rotate across the Southern
periphery of the longwave through the entire forecast period. The
Aleutians and Bering into Southwest Alaska will have locally
heavy showery precipitation, beginning as snow, but becoming mixed
as the lows moves across the Bering. Areas of Easterly gale force
winds accompany the front over the Bering, with Westerly gales
along and over the Aleutians and Alaska Peninsula, diminishing
Thursday. A North Pacific low brings in another front and the next
round of precipitation and winds to the Western Aleutians for
Thursday and Friday.

Low centers developing along the front South of the Alaska
Peninsula continue their Eastward trek into the Gulf of Alaska
through Friday. Some gusty winds spread over the Gulf, with
locally heavy precipitation starting as snow, but changing along
the coast and Eastern Prince William Sound accompanying the warmer
air intrusion ahead of the Gulf low through Friday. Kodiak Island
will have mixed rain and snow. Southcentral coastal areas start
with snow, but change to rain, with areas of snow further inland.
Significant accumulations from Prince William Sound and East are
expected. Interior areas will remain snow.

Kutz

&&

.AVIATION...

PANC...Heavy snow with LIFR CIGs and Visibility will end abruptly
this evening as the heavy snow area moves north and east of PANC,
however low stratus, areas of fog and scattered snow showers will
continue into the night. Expect mainly MVFR conditions for CIGS
and Visibility with occasional IFR condition as snow showers move
over the terminal tonight and mainly MVFR conditions tomorrow
morning and into early afternoon before another round of snow with
LIFR CIGS and Visibility pushes over PANC in the afternoon.

&&