Gale Warning 146, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
458 PM AKST Wed Feb 2 2022

.ANALYSIS AND UPPER LEVELS...

In the upper levels, there is a transient upper level ridge
building over Southcentral with its axis located on a northwest to
southeast orientation from Kodiak Island to the Kuskokwim Delta.
An upper level low with its corresponding surface low (~950mb)
continues moving northwestward through the western Bering Sea with
storm force winds. Deep, moist southerly flow is present between
the aforementioned upper level ridge and the upper level low. As a
result, this is keeping the Eastern Aleutians/southern Alaska
Peninsula to the Pribilofs and the Kuskokwim Delta unsettled
today. Strong interior high pressure is keeping a tight pressure
gradient on the surface with gusty northeasterly winds continuing
across the Kuskowim Delta. Some weak upper level shortwaves in
the flow aloft are producing snowfall heavy enough to result in
1/2 mi to 1/4 mi visibility at times along the Kuskokwim Delta
Coastline.

&&

.MODEL DISCUSSION...

Model guidance remains in decent agreement with the movement of
synoptic scale features out through Day 3. However, there are
differences that remain at the surface, especially in regards to a
low pressure system that is expected to develop Thursday afternoon
and track across the Gulf. THe NAM remains furthest west with the
low, EC and Canadian-NH were pretty close to each other and the
GFS was somewhere between the NAM and EC/Canadian-NH solutions.
The track the low takes will be crucial to the sensible weather
impacts expected across Southcentral. Tracking the low through
Thursday evening into Friday, models all do something different
with the NAM bringing the low closer to Prince William Sound, GFS
furthest east and close to Southeast Alaska. EC and Canadian-NH
were in the middle bringing the low towards Yakutat. Across
Southwest and the Bering, models remain in rather good agreement
on the placement and track of the next surface low Thursday
evening into Friday.

&&

.AVIATION...

PANC...VFR conditions are expected through around 03/18z Thursday
morning with some light snow developing. The light snow is
expected to pick up some in intensity around 03/18z which is
expected to bring the terminal to MVFR conditions potentially down
to IFR conditions, though this remains uncertain. Northerly winds
are expected to increase late Wednesday night/early Thursday
becoming gusty (up to 25 mph) through the remainder of the TAF
package.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Thu and
Fri)...

Models continue to zero in on the next winter storm system
for Southcentral on Thursday. An upper low over the eastern
Bering will bring a triple point low into Prince William Sound
Thursday through the early morning hours on Friday with increasing
snow and winds. This will once again bring a long duration of
light snow to most areas. Preceding the low, a barrier jet is
forecast to redevelop offshore of the coast with gales south of
the Kenai Peninsula and the Copper River Delta. Down-inlet flow
will also promote gale force winds across Cook Inlet for points
south of Point Bede. There remains uncertainty in forecast snow
amounts. As with the previous system the current thinking is for a
long duration of lighter snow with most areas receiving up to 2
to 3 inches over much of Southcentral while the higher elevations
of the Kenai, Chugach, and Wrangell mountains to see higher
snowfall amounts. The biggest impacts will come in the form of
blowing snow and reduced visibility. A blizzard warning is in
effect for Thompson Pass where winds gusting to 45 mph are
expected to bring visibility down to a quarter of a mile or less.
Blowing snow will also pose impacts along the Sterling Highway and
parts of the Seward Highway and road conditions could deteriorate
quickly. Finally, a Winter Weather Advisory is in effect for the
Copper River Basin where additional widespread light to moderate
snow will result in slippery road conditions and periods of
reduced visibility. While still a few days out, a much stronger
area of low pressure will move into Southcentral on Sunday. This
next system's current forecast track and strength will be more
favorable for heavier snow amounts, but models need to resolve its
position better before finer details can be ascertained.

&&

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

Blizzard conditions will continue to occur along the immediate
Kuskokwim Delta coast through late Wednesday afternoon. A brief
lull in blizzard conditions may occur early Wednesday evening, but
conditions should worsen again by Wednesday night with blowing
snow extending further inland to Bethel. Snow will begin near
Kipnuk tonight and will move north and east, reaching Toksook Bay
and Bethel by Thursday morning, and Hooper Bay by Thursday
afternoon. Additional snow accumulations of up to 8 inches along
the coast and up to 5 inches for Bethel and surrounding areas are
expected. Visibility reductions are expected to one-quarter mile
from Kipnuk to Hooper Bay (including Nunivak Island) and
reductions of one- half mile for areas east. Conditions should
begin to improve from south to north by Thursday night as the
front exits to the northwest. A Blizzard Warning has been issued
and is in effect until 1 AM AKST Friday.

Snow and blowing snow will develop along the northern Bristol Bay
coast by early Thursday morning. The snow is then expected to
move farther inland through Thursday morning with the heaviest
snow from Dillingham north and west. Precipitation is expected to
begin as snow for locations along eastern Bristol Bay. However,
warmer air is expected to work in by mid morning Thursday allowing
any snow to transition to rain. Colder air is then expected to
move back over the region Thursday evening with any rain along the
southern and eastern Bristol Bay coasts changing back to snow.
Precipitation will taper off from west to east through late
Thursday evening. A Winter Weather Advisory has been issued and
will be in effect from 1 AM to 6 PM AKST Thursday. Another
North Pacific low will move towards the Alaska Peninsula Friday
and bring with it another swath of warmer temperatures and
precipitation to Southwest Alaska Friday night into Saturday.

&&

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

As a North Pacific low tracks northwestward across the Bering,
storm force winds will follow north and west on the eastern edge
of the aforementioned low. Winds across the northern Bering and
along the Southwest coast, especially near the Kuskokwim Delta,
will remain gusty through Thursday night. Precipitation will
diminish along the western Bering tonight and amplify along the
northern/eastern portions of the Bering and along the Southern
Alaska Peninsula tonight through Thursday afternoon. Another
North Pacific low will move towards the Alaska Peninsula Friday
and produce gusty winds Friday into Saturday.

&&

.Marine (Days 3 through 5/Saturday through Monday)...

Gulf of Alaska: A well developed North Pacific low moves over
Kodiak Island on its way into Prince William Sound for Monday. Its
front moves to the North Gulf Coast by Sunday. Forecast
confidence is uncertain for the low's track and development.
Widespread high end southerly gales move over the Gulf becoming
westerly and diminishing Monday. Easterly storm force winds
develop along the North Gulf Coast on Sunday, with seas up to 22
feet.

Bering Sea: A well developed low in the western Aleutians moves
into the North Pacific for Monday. Arctic high pressure moves into
the Bering through Monday. Forecast confidence is uncertain for
the tracks and development of all lows. Widespread easterly gales
are expected over the Western Bering, diminishing by Monday. A
well developed low moving along the Alaska Peninsula brings seas
to 18 feet on the Pacific side through Sunday. A well developed
North Pacific low approaches the Central Aleutians Monday.
Widespread gales begin late Sunday into Monday. Seas building to
16 feet Monday.

&&

.Long Term Discussion (Days 4 through 7: Sunday through
Wednesday)...

The uncertainty continues for the long term pattern as there are
several key features of note, but continued poor agreement among
model solutions. A persistent 300 mb North Pacific jet in place
south of the Aleutians will create a favorable setup for an
active pattern. A broad upper level trough will be in place over
the Bering while anchoring this trough, several upper level lows
will spin up and lift into the Gulf. By Saturday, a strong Arctic
trough north of the state begins to extend southward, introducing
the potential for much colder air to surge southward over the
mainland for the weekend. This effort is quickly blocked,
however, as models are hinting at the potential development of a
North Pacific low tracking into the Gulf, which would introduce a
surge of warm southerly flow to the Gulf by early next week. In
summary, the signals in the noise are weak at this point, however
it is looking like an active weather pattern will continue into
the weekend and early part of next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...

PUBLIC...Blizzard Warning: 131 Thompson Pass 155.
         Winter Weather Advisory: 141 161.
MARINE...Gale Warning: 119 120 127 129-131 137-139 160 165 172 180
                       181 185.
         Heavy Freezing Spray Warning: 185
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MV
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS
MARINE/LONG TERM...KO