Gale Warning 190, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
800 AM AKST Tue Feb 28 2023

.ANALYSIS AND UPPER LEVELS...

A strong low is now centered near St. Matthew Island with it's
warm front extending from the Lower Kuskokwim Valley into
Southcentral. It's occlusion has now reached the Kuskokwim Delta,
where blizzard conditions were prevalent for much of the overnight
hours. A baroclinic leaf can be seen on Satellite south of Adak,
showing the early development of a strong system expected to move
into the Western Gulf tomorrow. What began as a clear night last
night over Southcentral has since become overcast with the front
moving into the area. As such temperatures have moderated and
warmed overnight.

&&

.MODEL DISCUSSION...

Models are now in good agreement overall and have clustered near
the GFS solution (which was the outlier) with each run. The key
feature that they were struggling with was the development of a
strong low over the North Pacific which will then move near or
over Kodiak Island early Wednesday morning and then along the
coast Wednesday into Thursday. The low is significantly stronger
that guidance was showing the past few days, with hurricane force
gusts now looking likely over the Western Gulf Waters and
potentially the western and southern shores of Kodiak Island.
There are still a few minor timing and locational differences
amongst the models, but overall they have cluster together.

&&

.AVIATION...
PANC...Light to moderate snow is expected to begin around 15Z and
will linger through the early afternoon. LIFR visibility is
likely for a period this morning due to the snowfall but should
return to MVFR in the afternoon as downsloping decreases snowfall
rates and raises ceilings. An additional storm is expected to move
into the Gulf Wednesday morning, which may return IFR to MVFR
visibility and ceilings. Winds are expected to remain light out of
the north.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Tuesday through Thursday night)...

Widespread snow is moving over the western half of Southcentral
this morning as an occluded front advances from the west. Snow
over Kodiak City this morning is expected to change over to rain
as the front lifts north of the island and easterly winds usher
in slight warmer, maritime air. A triple point low will then
develop along the front northeast of Kodiak Island and stall, its
front draped along the Southcentral coast, with snow and gust gaps
winds persisting along the coast. A vigorous upper-level moving
from south of the Aleutians toward Kodiak Island, along with its
attendant surface low, will then quickly move over Kodiak Island.
These feature will phase with the aforementioned low, allowing for
the development of a rapidly deepening surface low. This new 960
mb low will move toward Prince William Sound, wrapping storm-force
winds along its front and around the back side of the low.

For the coast, the snow will remain quite persistent, along with
gusty winds, through the duration of the event until the low moves
east late Wednesday or early Thursday. For inland locations from
the western Kenai Peninsula north to Talkeetna, this event will
likely be more of a one-two punch. The first, will be a burst of
moderate to heavy snow this morning, with several inches of
accumulation, especially along the western Kenai and across the
southwest facing foothills of the Talkeetnas. The snow should then
taper off a time this afternoon before filling back in for
Wednesday. As the low moves to close to the coast, northerly winds
along Cook Inlet and Resurrection Bay will also increase,
resulting in blowing snow for coastal western Kenai, Homer, and
Seward. The snow and gusty winds then shift to Thompson Pass and
the southern Copper River Basin for Wednesday, as light snow
lingers along Cook Inlet and the west facing foothills of the
Chugach and Kenai Mountains.

The other big story with this system is the expected strong winds
across Kodiak Island for Wednesday in the wake of the low. Strong
pressure rises will allow for strong gusts early Wednesday
morning across the island before diminishing slightly through
the afternoon. A shortwave trough moving from the Alaska
Peninsula into the western Gulf ,along with resultant cold air
advection, will bring a second peak in the stronger winds
Wednesday evening through early Thursday before the winds finally
begin to taper off.

A return of colder air and gusty outflow winds is expected for
the latter half of the week as the low exits the region.

&&

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

Gusty winds and periods of heavy snow have been observed across
Southwest Alaska over night and will continue through this
morning, gradually easing up into the afternoon hours. Blizzard
conditions along the Kuskokwim Delta coast will improve early
this morning, but light snow and increased winds are likely to
continue and blowing snow may be an issue at times. Conditions
across Southwest Alaska as a whole are expected to improve tonight
into Wednesday morning, with some residual wrap around snow/winds
along the Kuskokwim and Kilbuck Mountain Ranges and portions of
the Kuskokwim Delta, primarily Bethel, that may produce another
quick round of blowing snow.

&&

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

Active weather continues across the Bering Sea and Aleutian Chain.
A band of storm force winds passing over the Pribilof Islands has
bumped them up to High Wind Warning criteria so a product was
issued for the area through mid-morning. Widespread gale force
winds and precipitation (both rain and snow for some areas along
the Aleutian Chain) will continue through Wednesday morning. The
next system moves over the Western Aleutians late Wednesday
morning. While it will be weaker then the current system, there
will still be a small area of storm force winds and widespread
gale force winds.

&&

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

Models have come into better agreement for the long-term in terms
of synoptic features, but are still struggling with the finer
details. By Friday afternoon the leading front of a northern
Bering low approaches Southwest Alaska. This front will bring
widespread light showers from the Kuskokwim Delta, to the Lower
Kuskokwim Valley and Greater Bristol Bay region through Saturday
afternoon. This wave is expected to break-up along the Alaska
Range, and not extend into Southcentral. High confidence is had
that a ridge of high pressure will build over the Mainland and
bring warmer temperatures to Southwest. These temperatures may be
moderated by shortwaves that traverse over the ride near the
Kuskokwim Delta/Valley, but the Bristol Bay region and AKPen are
expected to be "warmer". The aforementioned ridge will also aide
in keeping much of the activity out of Southcentral during this
period. Late Saturday evening a North Pacific low will surge
towards the Western/Central Aleutians, bringing widespread light
precipitation and southerly gales from Adak to Unalaska lasting
until Sunday morning. Precipitation associated with this system
will likely be blocked to the east, with only a few showers
possibly reaching the Southwest coastline late Sunday morning.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Blizzard Warning: 125
         Winter Weather Advisory: 121 131 141 152 161 171
         High Wind Warning: 171 195
MARINE...Storm Warning: 119 120 131 132 150 155 170 171 178 179 351 352 412 414
         Gale Warning: 125 130 136-139 141 160 165 172-177 180 181 185 411 413
         Heavy Freezing Spray: 127 130 139 414 160 179 180 185
FIRE WEATHER...NONE.

&&

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

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
1230 PM AKST Tue Feb 28 2023

AKZ101-010900-
Anchorage-
Including the cities of Anchorage, Eagle River, Indian,
and Eklutna
1230 PM AKST Tue Feb 28 2023

...PERIODS OF BLOWING SNOW FOR THE ANCHORAGE HILLSIDE AND SEWARD
HIGHWAY...

Gusty winds across the Anchorage hillside and along the Seward
Highway corridor along Turnagain Arm will produce brief periods
of blowing snow with the higher wind gusts, which could reduce
visibilities. Please use caution while traveling.

A secondary wave will bring more snow on Wednesday morning, with
moderate uncertainty regarding the location of the heaviest bands.
Additional snowfall of 2 to 4 inches is expected through
Wednesday night, though locally higher amounts are possible,
especially along the Anchorage Hillside. Fluffy, loose snow could
lead to higher snow totals. Forecast snow amounts may change as
this low progresses east. Please check back for the latest
forecast.

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
249 PM AKST Tue Feb 28 2023

AKZ101-010900-
Anchorage-
Including the cities of Anchorage, Eagle River, Indian,
and Eklutna
249 PM AKST Tue Feb 28 2023

...PERIODS OF BLOWING SNOW FOR THE ANCHORAGE HILLSIDE AND SEWARD
HIGHWAY...

Gusty winds across the Anchorage Hillside and along the Seward
Highway corridor along Turnagain Arm will produce brief periods
of blowing snow with the higher wind gusts, which could reduce
visibilities. Driving on dry, fluffy snow could resuspend snow
and reduce visibility as well. Please use caution while traveling.

A secondary wave will bring more snow on Wednesday morning, with
moderate uncertainty regarding the location of the heaviest bands.
Additional snowfall of 2 to 4 inches is expected through
Wednesday night, though locally higher amounts are possible,
especially along the Anchorage Hillside. Fluffy, loose snow could
lead to higher snow totals. Forecast snow amounts may change as
this low progresses east. Please check back for the latest
forecast.

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
254 PM AKST Tue Feb 28 2023

AKZ111-145-010900-
Matanuska Valley-Susitna Valley-
Including the cities of Palmer, Wasilla, Sutton, Chickaloon,
Talkeetna, and Willow
254 PM AKST Tue Feb 28 2023

...REDUCED VISIBILITY DUE TO RESUSPENDED SNOW FROM VEHICULAR
TRAFFIC POSSIBLE ALONG AREA ROADWAYS THIS EVENING...

Snow across the Mat-Su Valleys may result in hazardous driving
conditions during the Tuesday evening commute. The dry, fluffy
nature of the snow may result in reduced visibilities along area
roadways due to resuspended snow from vehicular traffic. Motorists
are urged to slow down and use caution.