Gale Warning 769, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
452 PM AKST Wed Dec 7 2022

.ANALYSIS AND UPPER LEVELS...

An upper low is currently becoming cut off over the Gulf and
taking most of the energy from the previous Southcentral system
with it. Snow will continue to taper off through the evening. Its
associated surface low combined with relatively high pressure to
the north is leading to increased outflow winds, particularly
through terrain gaps and passes. Conditions are mostly quiet out
west with only a few ocean-effect snow showers along the coast and
the AKPEN. A low is bringing precipitation as well to the far
western Bering/Aleutians.

&&

.MODEL DISCUSSION...

High-res models indicate snow lingering longer near the Anchorage
hillside this afternoon. Otherwise, models are in general
agreement on larger-scale features.

&&

.AVIATION...

PANC...Gusty northwesterly winds up to 25 kts will continue
through through this evening before diminishing by Thursday
morning. VFR ceilings/visibilities will persist.

&&

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

An upper-level short-wave situated over the southeastern Gulf
continues to track eastward through tonight. Snow associated with
a surface low located near the region will taper off for most
areas by this evening, though light snow will linger longer in the
Copper River Basin due to continued weak cyclonic flow aloft on
the north side of the exiting aforementioned low along with
upslope flow on the north side of the Chugach Mountains. However,
significant additional accumulations are not expected. Strong
gusty gap winds through area mountain ranges, along with
widespread strong winds across the Gulf, will become apparent this
evening as cold air advection behind the low takes hold and
pressure gradients tighten. Expect the strongest winds to be
through coastal bays, including Resurrection Bay, Passage Canal,
and the Valdez Narrows/Arm. Gusty northwesterly winds in north to
west Anchorage this evening are also possible as strong upper-
level forcing is favorable. The chances for blowing snow to
accompany these winds in localized areas is high and motorists are
urged to use caution while traveling. As we move further into the
forecast period, an upper-level ridge will amplify over the
eastern bering/western Alaska. This will result in maintaining
strong northerly flow and will bring another round of cold air
advection with elevated gap winds to the region. Expect
temperatures to decrease as skies become clearer due to the
aforementioned ridge, which will lead to sub- zero temperatures
inland and single digits to teens likely elsewhere by week's end.

&&

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

Northwesterly flow will prevail and other than a hit or miss
shower, rather quiet weather is expected for Southwestern Alaska
through the end of the work week. As high pressure builds into the
area, temperatures will trend slightly cooler over the next
couple days with single digits above and below zero Friday
morning. Highs will generally dip into the teens Thursday and
inland areas Friday. A transition to warmer temperatures may
arrive to the coast Saturday with the next front this weekend.
Breeziness and precipitation will also accompany the front.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...

Model agreement has improved compared to the past couple days.
The low with its front along the Aleutian chain is not expected to
cross into the Southern Bering. Rather, the low center will
maintain some strength and track along the Aleutian chain to the
Eastern Aleutians before turning south and weaken. Winds,
especially along the Bering side of the Aleutians could see some
gale force winds and precipitation. There is subtropical moisture
drawn into this system and a plume of precipitation is expected to
span into the Southern Bering but should remain south of the
Pribilofs tonight into Thursday. Another, more vigorous low from
the North Pacific will follow shortly after and track north into
the Bering. At this time, the low center tracks north along the
Western Bering. Precipitation and southerly gale winds are
expected with storm force gusts along the front. The front appears
to track across the Bering Sea through the Pribilofs, St Matthew,
and Nunivak Island and the Southwestern coast by Saturday. This
has been trending a little stronger than previous model runs, but
the forecast is still a few days out and have only recently come
into better agreement.

&&

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

An active weather pattern will continue over the latter half of
the weekend into next week across Alaska. Models continue to
advertise a North Pacific low lifting into the Gulf of Alaska
Sunday into Monday while a broader trough lifts from the Northern
Bering into the Chukchi Sea. Colder temperatures are anticipated
over the Bering as northwesterly flow follows in the wake of the
departing low into the Chukchi Sea. Enhanced westerly flow into
the coast of Southwest Alaska is a possibility on Sunday with
potential storm force winds for a short period.

Meanwhile, an impressive plume of moisture is forecast to
accompany the North Pacific low as it pushes into the Gulf Coast
through Monday. Models are advertising 24 hour QPF amounts of 2
to 4 inches as the low tracks from near Kodiak, to Prince William
Sound and into Southeast Alaska. As temperatures are expected to
remain cold, this could produce some significant snowfall for
Southcentral. However, more run to run consistency in model output
would be ideal to increase confidence levels. Regardless,
operational models such as the GFS, is splashing precipitation
across all of southern Alaska Sunday night and Monday morning with
the highest amounts over the coastal regions. Gap winds may also
become a concern for parts of the Eastern Aleutians and Alaska
Peninsula on Monday and Tuesday with cold air advection helping to
spill enhanced drainage winds into the Gulf of Alaska.

Attention then turns back to the Aleutians with the next upper
trough tracking just south of the Aleutian Chain Tuesday into
Wednesday. Some models want to close off this low south of the
Central Aleutians, effectively stopping its eastward progress
before diving it southward into the North Pacific. A threat for
rain and snow may exist ahead of the low with strong southerly
flow and warm air advection lifting into the Southern Bering
Tuesday into Wednesday of next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood Advisory 155.
MARINE...Gale 120 121 127 129 132-139 150 170 172 173 175-178.
		 Storm 130 131
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...AP
SOUTHCENTRAL ALASKA...NS
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...VR
LONG TERM...BL