Gale Warning 141, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
522 AM AKST Tue Feb 1 2022

.ANALYSIS AND UPPER LEVELS...

This morning on satellite imagery, there is a mature near St
George Island with an occluded front over the central and eastern
Bering. There is a second low south of Adak and a third low that
is west of Shemya.  There is an area of high pressure from the
Bering Strait to the Yukon Territory. There is a jet core south
of the Alaska Peninsula with a magnitude of 120 knots. There is a
second jet core over the northwest Pacific with a magnitude of 190
knots. On ASCAT (Advanced Scatterometer) an area of storm and
gale force winds that was detected west of the Attu Island
associated with a 964 mb surface low. There is a second area of
storm and gale force winds south of Atka associated with a 946 mb
low.

&&

.MODEL DISCUSSION...

The models continue to show a very active pattern for the Bering
and a transition for Southcentral Alaska. Model guidance remains
in good agreement on the synoptic scale features over the Bering,
North Pacific and Gulf Of Alaska through 48 hrs. The main
forecast challenge will be determining the P-type (precipitation
type) for the front moving into Southwest Alaska where freezing
rain will be possible and the P-type will transition during the
event. Otherwise, past 24 hrs there is some minor model
divergence regarding the timing and the track of the lows emerges.

&&

.AVIATION...

PANC...A frontal boundary is pushing towards PANC and cigs will be
reduced. Light snow is expected at the terminal today and will
taper off by 12z on Feb 2nd. Degraded flight categories expected
with this event. Amendments will be made as needed.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Tue and
Wed)...

A robust shortwave is set to bring widespread snow back over
Southcentral as we head through today. The main impacts look to be
blowing snow through Thompson and Turnagain Passes. There will
also be some moderate to heavy snowfall along the extreme Western
Kenai Peninsula. Blowing snow will also be possible in this area
as gusty NE winds develop through Cook Inlet. Please check out the
Winter Weather Advisories in effect for details.

As the shortwave lifts north through the day today, it will push a
warm front towards the North Gulf Coast. A surface low will
develop just east of Kodiak along the front later today and track
quick towards Yakutat by late tonight. The front itself is already
starting to increase winds across many of the marine zones. Storm
force winds will be possible near the Barren Islands as well as
along the barrier jet region near Cordova. The front will also be
responsible for pushing quite a bit of precipitation into Western
Prince William Sound and the Portage Valley. The development and
track of the surface low are important with this storm system
because it will influence the amount of warm air trying to make it
inland. As the low takes shape, it will shunt the warm air off to
the eastern Gulf and allow most places to remain below (or close
to) freezing. The few exceptions could be right along the coast
(Kodiak and Whittier) who could potentially see some rain mix in
if the winds remain onshore. So ultimately, this will be a snow
event for most locations. Accumulations should range generally
between 1-3 inches with higher amounts (6+ inches) along Cook
Inlet near the Western Kenai and through Portage Valley/Turnagain
Pass. Due to the location of the surface low, some weak
downsloping is expected to take a bite out of the amounts for the
Mat-Valley and Anchorage. While much of Anchorage should see
around 2 inches, the Mat-Valley will struggle to get more than an
inch.

This system quickly exits to the east on Wed. This will make for a
dry day for nearly the entire area with some low clouds and patchy
fog a possibility. Some breezy offshore winds will be possible
along the favored coastal sites. Then another system that looks
very similar to today's will start to move towards Southcentral
late Wed into early Thu. This could spell another round of
widespread, light snow.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

A weakening front moves along the Southwest Coast today as its
parent low moves northwards across the Bering Sea. Periods of
lingering freezing rain will persist for Bethel and Dillingham, as
well as immediate surrounding areas, through the early morning
before transitioning to all snow. Areas south of Igiugig down to
Port Heiden (including King Salmon) have already switched to rain
and will continue to see persistent rainfall through much of the
day today before tapering off from south to north into tonight.
Gusty winds will continue across Bristol Bay and the Kuskokwim
Delta today, diminishing by tonight. Areas of blowing snow along
the Kuskokwim Delta coast from Toksook Bay to Hooper Bay are
causing some visibility reductions this morning and will likely
continue until winds begin diminishing this evening. Conditions
across the Southwest Mainland are expect to improve briefly on
Wednesday until another North Pacific low moves over the Southern
AKPen Wednesday night. This system is carrying another round of
warmer air, though not quite on the same level as the former. Rain
is likely to push south to north along the AKPen as far north as
King Salmon. It is still uncertain whether or not enough warm air
will make it to Dillingham and bring another round of freezing
rain or if it will stay all snow by early Thursday morning.
Elsewhere across Southwest will remain as all snow, with more
blowing snow possible in the Kuskokwim Delta on Thursday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

The first of two separate North Pacific lows pushes towards the
Central Aleutians tonight. High end gale force winds and
widespread precipitation hit the Central Aleutians/Southern
Bering later this evening, quickly followed by an area of storm
force winds just west of Atka. This area of storms travels along
the eastern edge of the low and moves north/northwestward along
the Central Bering through Wednesday evening. Additionally, as
the low moves north, flow over Shemya and the Western Aleutians
becomes northerly. At this point, there is a chance for some
blowing snow to occur until flow becomes southerly again.

The second system moves over the Southern AKPen Wednesday night
and will bring areas of gale force winds and heavy precipitation
from Unalaska to Port Heiden by Wednesday afternoon. There is a
warmer air behind the front that may allow for areas of rain along
the lower elevations, while the higher elevations will remain all
snow. Precipitation will spill into Bristol Bay and travel up the
Southwest Coast Wednesday night and Thursday.

&&

.MARINE (Days 3 through 5 - Thursday through Saturday)...

Gulf of Alaska:

A well developed low tracks along the North Gulf Coast through
Saturday. Forecast confidence decreases with the low track and
development through the period. Gale force barrier jets through
Lower Cook Inlet, Barren Islands and Shelikof Strait diminish
Friday. Seas to 14 feet through Cook Inlet and Shelikof Strait
subside Friday.

Barrier jets develop along the Eastern North Gulf Coast ahead of
the low through Saturday. A front moves across the Gulf through
Saturday. Widespread high end gales extend across the Gulf through
Saturday, Seas to 20 feet, subsiding.

Bering Sea/Aleutians:

A well developed Western Bering low complex weakens as it swings
around to the South side of the Western Aleutians by Saturday.This
low pulls a second low across the Alaska Peninsula into the
Bering through Saturday. Forecast confidence is uncertain due to
the tracks and development of the lows. Widespread high end gales
across the Bering with areas of storm force winds around the
Western Bering low diminish from East to West over the Bering by
Saturday. Seas to 30 feet over the Western Bering, subsiding. The
Eastern low has gales on both side of the Alaska Peninsula,
diminishing. Seas to 20 feet, subsiding Friday.

A new low approaches the Eastern Aleutians late Friday, and
tracks along the Alaska Peninsula Coast through
Saturday.Widespread gales near shore, with areas of storm force
winds offshore. Seas to 25 feet through Saturday.

&&

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

Looking ahead at the extended forecast, little has changed with
the overall pattern as active weather for the southern half of
the state is still anticipated. Models continue to show a 300 mb
North Pacific jet positioned south of the Aleutians on Friday that
moves northeastward over the Gulf and Southcentral through
Saturday, exiting into Canada. An associated surface low is
located in tandem with the jet's left exit region and upstream of
an upper-level ridge as it tracks along the south side of the
Aleutians on Friday. Early on Saturday, the low moves across the
Southwest/Southcentral and dissipates. In summary, this system
will bring a round of widespread precipitation from west to east
across the southern half of the state as it tracks eastward.

From Friday through Sunday night, there is a low pressure system
located just southwest of Shemya that remains nearly stationary
for the entire three days until another low approaches the central
Aleutians from the North Pacific. The front extending from this
low will push northeastward along the Aleutian Chain and into
Southwest/Southcentral through Monday. A broad ridge starts to
build over the Gulf late on Monday.

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 121 131 155 161
MARINE...Storm Warning 119 131 173 174 175 412 413
		 Gale Warning 120 127 130 130 132 137 138 139 141 170 172 177 179 185
					  351 411 414
		 Heavy Freezing Spray Warning 130 185
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PJS
SOUTHCENTRAL ALASKA...MSO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KM
MARINE/LONG TERM...KZ/AF