High Wind Watch 5, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
555 AM AKST Wed Feb 15 2023

.ANALYSIS AND UPPER LEVELS...

An amplified pattern persists over the region with a longwave
trough centered over the Bering Strait and a deep low located near
the western Aleutians. Satellite Imagery is showing a plume of
moisture spreading across the western and central Aleutians in
association with the low downstream. The aforementioned low's
front is stretching eastward over the western/central Aleutians,
and will be the focus for active weather for not only the Bering
Sea and Aleutians, but also Southcentral later in the week. Radar
returns are shown over the western Kenai Peninsula and near
Cordova as energy overhead continues to bring light snow showers
to the area.

&&

.MODEL DISCUSSION...

Models seem to be handling the overall synoptic pattern well, but
are struggling with the finer details. Out west, their is a
potential for higher winds to impact the central Aleutians around
Friday afternoon due to a low tracking northwards across the
Chain. Model spread grows in regards to the track of the low in
relation to the Pribilof Islands. The NAM/GFS are having the low
track above the Islands, whereas the Canadian and EC are having
the low stay south of the Islands. This impacts where the
strongest winds will be with this system. For the east, models are
having a hard time handling the front pushing through Thursday
night into Friday in relation to where the precipitation will
occur. A blend of the GFS/NAM are currently the models of choice
as it is the middle ground solution and seem to be in the best
agreement.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist through
this morning. Chances for light snow increase around mid-day
today with the potential for ceilings to drop to MVFR conditions.
However, conditions will likely stay VFR with flurries.

&&

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

A surface low lingers in the northern Gulf is keeping unsettled
weather for Cook Inlet, Kenai Peninsula, and eastern Prince
William Sound. Accumulations are expected to be on the lighter
side. The next system arriving to Southcentral will be the next
forecast focus in the near future. Plenty of moisture will advect
into the area with a front and southeasterly flow. Agreement is
also coming together for increased southeast winds. This is coming
from a trough that develops off the energy and moisture fetch
from a strong low near the western Aleutians. As the major low
stalls, this low spins up and ejects the moisture and energy
toward Southwest Alaska. The trough negatively tilts into the Gulf
of Alaska and a new low develops near Kodiak Island Thursday
night. There is still some uncertainty in the strength and
position of the low, but the general synoptics remains.

&&

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

Precipitation will taper off from west to east this morning as an
upper-level ridge builds across the region from the Bering.
Clearing skies and dry conditions will be quickly brought to an
end a Bering surface front approaches the region. The front is
expected to lift across the Alaska Peninsula starting this evening
and then reach the Southwest coast around midnight tonight.
Elevated winds and snow are expected to accompany the front before
it tracks farther inland and dissipates on Thursday morning.
Another system, which is trending stronger than the aforementioned
one, will initially reach the Alaska Peninsula on Thursday
afternoon and then track to the Southwest Mainland by Thursday
night. This stronger front is expected to spread heavy snow and
gusty winds across much of Southwest as it lifts to the northeast
across the region through Friday morning. Precipitation will
likely linger across the Southwest Mainland through Friday as the
system exits to the north. On Friday evening, a North Pacific low
approaches the Alaska Peninsula and extends it front northward
into Saturday.

&&

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

A strong front extending off a Kamchatka low pushes east across
the Central and Eastern Aleutians this morning. Gusty
southeasterly winds and snowfall with the low are expected to
bring blizzard conditions to the Pribilof Islands this morning
through the evening. The front will continue east to the Southwest
Mainland and weaken tonight into Thursday morning. The low itself
will linger near the Western Aleutians and Bering through
Saturday, maintaining elevated winds and precipitation for that
general region through the short term period. Recent model runs
advertise a North Pacific low developing near the Central
Aleutians on Thursday morning. Model agreement with the exact
low track begins to diverge already by Thursday afternoon, however
the low generally looks to track near the Pribilof Islands on
Friday night and then towards the Eastern Bering. Gusty winds and
heavy precipitation are expected to accompany the low.

&&

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

The key features of the long term include a building upper level
ridge over the Gulf on Saturday with a broad upper level trough
over the northern Bering. Initially for the beginning of the
period, the jet stream remains south of the Aleutians and briefly
traverses the southern mainland before shifting south over the
Gulf on Sunday. Nonetheless, a mostly active pattern will continue
into early next week as several North Pacific lows lift northward
into the Bering and the Gulf.

By Saturday night, a fast-moving North Pacific low remains south
of the Aleutians and arrives over the Alaska Peninsula. This low
then tracks northeastward into the Gulf, bringing the potential
for precipitation for the southern mainland - from the Alaska
Peninsula eastward to Prince William Sound coast. Depending on the
position of this low as it reaches the Gulf, precipitation may
spread farther northward into the Susitna Valley and Copper River
Basin.

Moving into Sunday, scattered showers look to persist across the
Bering and Southwestern coast, however both the GFS and EC
advertise a building an upper level ridge over the Bering early
Monday morning. Meanwhile a potent low arrives over the western
Aleutians and is quickly driven into the northern Bering by Monday
night. If this setup pans out and the ridge strengthens as
currently advertised, a highly amplified pattern will take shape
for Tuesday as multiple North Pacific lows are steered into the
Bering. Meanwhile much of the mainland may see calmer (though
likely colder) conditions as offshore flow prevails through late
Tuesday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Blizzard Warning: 195.
MARINE...Gale Warning: 130, 155, 170, 172-177, 179, 185, 412-114.
		 Storm Warning: 178, 411.
		 Heavy Freezing Spray Warning: 130, 138, 150, 160, 165,
 	     179, 185, 411-414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...NSC
SOUTHCENTRAL ALASKA...VR
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AF
LONG TERM...KO