FXAK68 PAFC 271345
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
445 AM AKST Thu Jan 27 2022
.ANALYSIS AND UPPER LEVELS...
A strong ridge of high pressure is entrenched over the Bering Sea.
A trough of low pressure is oriented north-south across the
central part of the state, just to the east of the blocking high
over the Bering. A large low pressure system south of Kodiak is
moving north across the western Gulf, while another strong low
pressure system is south of Attu Island, moving northwest.
Precipitation, mainly in the form of snow continues across much
of South Central, with the heaviest confined to the eastern Kenia
and PWS areas. Farther inland conditions were generally dry.
Temperatures were mainly in the teens and 20s over Central and
South Central, the exception is eastern Prince William Sound with
temps in the 30s and rain. Temperatures across southwest Alaska
ranged from the single digits to teens above zero, to the single
digits and teens below zero in far southwest Alaska. The Aleutians
saw readings generally in the 20s and 30s.
Models remain in good agreement with the handling of synoptic
features through Saturday. A ridge of high pressure remains in
place over the Bering Sea. The upper level trough, stretching
north-south across central/western Alaska will remain in this
general area through today. The trough will wiggle somewhat as a
reinforcing impulse of energy moves south along the trough and the
low pressure system moving north across the western Gulf gets
wrapped up into the southern portion. As these two features merge,
models show the result as a large low pressure system with
multiple impulses of energy rotating around the center over the
western Gulf through Saturday drawing moisture in from the Gulf
of AK. This creates a widespread, long duration event over
Southcentral which will persist through Friday for Anchorage and
the Valley, and through Saturday for coastal areas from the
Eastern Kenai eastward. While this is a favorable setup for snow
for Southcentral, due to the subtle differences in the evolution
of the impulses of energy, uncertainty remains as to exactly
where the highest snowfall amounts will be.
Farther west, the Storm force low south of the western Aleutians
moves northwest today. Models show multiple low pressure systems
developing over the North Pacific, south of the western and
central Aleutians, each moving north then northwest, due to the
blocking high over the Bering.
PANC...Predominantly MVFR conditions expected through the TAF
period, although conditions will drop to IFR during periods of
heavier snow. Due to the weather pattern, it is difficult to
pin point the periods of heavier snow. Conditions will begin to
improve late this evening.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Upper level North Pacific low moving northward is overspreading
precipitation across Southcentral Alaska. The associated inverted
trough is producing gusty winds through Thompson Pass as well as
down Cook Inlet (mainly western Kenai). Snow and blowing snow is
a resultant concern for both of these areas through tomorrow
morning. Heaviest snow through Thompson Pass is expected today
before tapering off and becoming light tonight. Winds will
continue to be gusty beyond Friday and any transportable snow may
create reduced visibilities at times. Western Kenai will see snow
and pockets of isolated blowing snow across the inland areas, but
the worst conditions will be near Cook Inlet, more specifically
from Nikiski to Anchor Point. Winter Weather Advisories have been
issued for both areas and will remain in effect until Friday
morning. A third Advisory is in effect for the Copper Basin, for
snow accumulations of 6-12 inches along the Richardson Highway
near Glennallen, as well as for blowing snow from Paxson north to
A polar trough dives south across Southwest Alaska Thursday night
and Friday and will reinforce cold air across Southcentral.
Any forcing for precipitation across Anchorage, Kenai, and the
Mat-Su Valleys will be cut off by Friday as the low moves south
of the AKPen, but will allow for continued precipitation across
the North Gulf Coast (including eastern Kenai) into Saturday
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3:
Today through Saturday)...
An upper level trough extends from the interior into Southwest
Alaska with a low pressure system over the Gulf. This system is
bringing some mid and high level clouds to parts of Bristol Bay
and the AKPen and some lower clouds over the Lower Kuskokwim
Valley. An upper low will develop over Bristol Bay tonight and
Friday as colder air reinforces the trough. This will bring
chances of light snow to eastern portions of Bristol Bay from
Iliamna to near King Salmon but very little accumulation is
expected. Cold air advection is expected to move across the area
tonight and Friday which will bring colder air and wind chills to
near -30 in some areas. Additionally, gusty winds will continue
out of the north. On Saturday the low pushes into the Gulf with
gusty winds continuing for the Kuskokwim Delta, but lighter winds
across Bristol Bay. Otherwise dry conditions expected on Saturday
with a few lingering clouds.
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Today through Saturday)...
A front will slowly move north across the western Aleutians
through tonight with Gales across the western Bering and western
Aleutians as well as areas of light rain. Meanwhile high pressure
will dominate the central portions of the Bering and Aleutians
through Saturday with low clouds expected. Out to the east over
the AKPen cold air will filter across the area on Friday and
Saturday and create gusty gap winds south of the AKPen with
pockets of storm force gusts out of the gaps up to 60 kts as well
as heavy freezing spray. Late Friday into Saturday another storm
force low will across the western Aleutians this low will track
northwest across the western Bering on Saturday, expect mainly
Gales but pockets of storm force winds possible near the low.
.MARINE (Days 3 through 5 - Saturday through Monday)...
Gulf of Alaska:
A weakening low tracks across the Gulf through Monday. Forecast
confidence is good. Gusty Northwest gap winds expected through the
Barren Islands and near Sitkinak for Sunday. Gusty Westerly winds
spread across the Southern Gulf through Monday. An Easterly
Barrier Jet forms along the Alaska Peninsula into the Eastern
Aleutians for Monday.
A well developed Central Aleutian low moves to the Central
Kamchatka coast for Monday. Widespread gales from the Pribilofs
west through Monday, with areas of storm force winds near the
western Aleutians, diminishing Sunday. Seas building to 25 feet
Sunday over the Western Bering, subsiding Monday. Seas on the
Pacific side of the Aleutians to 20 feet, subsiding Sunday.
A North Pacific low approaches the Central Aleutians for Monday.
Forecast confidence is low, due to the low`s track and
development. Winds and Sea state are uncertain with this low.
.LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)...
A quite interesting pattern is expected as multiple upper level
short-wave troughs advance through the forecast area for the long
term. Upper ridging from the North Pacific transiting from west
to east (eastern Bering through Southcentral) could create a
challenging forecast especially for P-type and snowfall amounts.
Rapid moving short-wave troughs aloft combined with CAA could
bring considerable snowfall amounts across Southwest and
Southcentral. Dry but cooler temperatures could likely linger over
Southcentral, but somewhat rising temperatures and increased
weather activity is possible over Southwest through Wednesday.
Stronger winds and elevated seas are expected over the
Bering/Aleutians, posing stronger gap winds for much of the
Aleutian Chain through Wed.
PUBLIC...Winter Weather Advisory 121 131 141.
MARINE...Gale Warning 119, 130, 138-139, 150, 155, 160, 175-178,
180, 185, 411-413.
Heavy Freezing Spray Warning 130, 138-139, 150, 160, 165,
179, 185, 412, 414.
SYNOPSIS AND MODEL DISCUSSION...NR
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RC