Gale Warning 857, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
551 AM AKST Wed Dec 28 2022

.ANALYSIS AND UPPER LEVELS...

There are a multitude of low pressure systems embedded within the
longwave pattern moving into and out of both the Gulf of Alaska
and the Bering Sea through the end of the week, that will bring
impacts to Southcentral Alaska, Southwest Alaska, and the Aleutian
Chain. For starters, the remnants of the Gulf low will continue
dissipating through this morning, with lingering precipitation
along western Prince William Sound (PWS). Meanwhile, the low
situated over the Western Aleutians will spend the day weakening
and merging with a North Pacific low approaching the southern
Alaska Peninsula. This system stretches and becomes elongated,
with a front extending south of the southern Gulf, that will bring
another round of precipitation to the eastern Kenai Peninsula and
western PWS. The models are hinting at the development of a
mesolow(s) developing within the front, with poor agreement on
center location(s).

&&

.MODEL DISCUSSION...

Models are in good overall synoptic agreement through the short
term, mainly in the upper levels. There remain inconsistencies at
the surface levels, with pinpointing embedded mesolows within the
longwave pattern. There is better agreement with the low in the
northern Gulf early this morning before dissipating. The general
track of the low tracking towards the southern Alaska Peninsula is
still pretty rough, but looks to be slowly starting to come
together. There are multiple low centers along the front extending
into the southern Gulf, however, that continue to be in disarray
as they are developing.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: This
morning through Thursday night)...

The remnant Gulf low is gradually dissipating and lifting
northward over Southcentral this morning. This has produced some
light showers across the Kenai Peninsula and southern Susitna
Valley, however the bulk of precipitation today will be
concentrated over Prince William Sound and the northern Gulf
coast. Additionally, dense fog has developed over the western
Kenai Peninsula from Soldotna south to Homer.

By this afternoon, attention shifts to a frontal boundary
associated with an Aleutian low. As the front spreads across the
Gulf, gusty easterly winds and rain will reach impact Kodiak
Island. As the front lifts northward, enhanced winds are expected
through the usual channels and gaps including Shelikof Strait,
the Barren Islands, and Kamishak Bay. By this evening,
precipitation will reach the northern Gulf coast. With warm
easterly flow, precipitation is expected to fall as rain across
coastal locations. While there is some chance for light snow
today, much of the western Kenai Peninsula and Anchorage Bowl will
see a downsloping effect. Meanwhile locations along the foothills
of the Alaska Range and the southern Susitna Valley can expect a
few inches of snow tonight.

By Thursday, winds over the Gulf should weaken significantly.
Models have not been great at handling this current pattern as
several lows are spinning up within the broad trough currently
over the Bering, however the key takeaway for Southcentral is
that an unsettled weather pattern will continue through the end of
the week.

&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Saturday)...

A ridge continues to build over southwest Alaska from the eastern
Bering. Low stratus and patchy fog will be slow to clear out, but
offshore winds developing Wednesday and strengthening into
Thursday will help bring clearer and drier conditions.
Temperatures will climb into the teens and 20s for today and drop
into the positive teens for tonight. An elongated trough will set
up over the Bering and keep systems out of the forecast area.
However, today, a front will track over the Alaska Peninsula and
bring southeasterly gap winds, in addition to rain through Friday.
Models continue to struggle with tracks and positions of
developing lows associated with the Bering trough, but overall
consensus is had that the majority of the mainland will remain
relatively quiet for the rest of the week.

&&

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

An elongated trough will set up over the Bering and be the
dominant feature for the week ahead. Satellite Imagery shows a
North Pacific low currently south of Nikolski and is expected to
continue to lift north and then east along the eastern
Aleutians/Alaska Peninsula. Highest winds and precipitation look
to stay confined to the aforementioned areas, but models continue
to struggle with the evolution of this feature. However, consensus
is had that cold, northerly flow over the relatively warm sea
surface temperatures will help to generate widespread showers
over the western Bering/ western Aleutians through Saturday along
with widespread small craft winds located around the elongated
trough.

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

Operational models remain in a decent agreement regarding the
upper-level disturbed pattern approaching the Bering from the
North Pacific. A broad area of low pressure with multiple low
centers at the surface is represented in each model with mild
spatial uncertainty. Agreement is strong that the surface low
complex will advance to the northwest, then stalling near the
southern tip of the AKPEN Sunday night/Monday morning. A leading
front on the northeastern side of the low will push into
Southcentral Sunday. This unsettled pattern will continue for much
of the week in Southcentral Alaska with onshore flow promoting
moderate to heavy precipitation along the coast. Drier conditions
inland are possible, however currently its difficult to tell how
downslope flow will influence impacts. Southwest Alaska will
expect windy and wet conditions along the AKPEN, however further
inland should be sufficiently downsloped. In the Bering, this
broad low pressure system will likely promote a general wet
pattern for the weekend and early week. By Monday morning,
northerly flow will develop in the Bering, providing a favorable
environment for showers along the Aleutians and Pribilofs as well
as gusty winds through gaps and passes depending on the intensity
of the cold air moving in.

&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Dense Fog Advisory: 121
MARINE...Gale Warning: 120 130 131 132 137 138
					   150 155 177 351 352
		 Heavy Freezing Spray Warning: 160 180 181 185
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KM
SOUTHCENTRAL ALASKA...KO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS
LONG TERM...CL