Blizzard and Winter Storm in Alaska, March 26 to 28, 2022

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
545 PM AKDT Fri Mar 25 2022

.ANALYSIS AND UPPER LEVELS...

A vertically stacked low over the northwest Gulf of Alaska
is weakening as it drifts westward toward the Alaska Peninsula
and Bristol Bay. Colder air aloft has wrapped all the way around
the low center and is spreading north into Southcentral Alaska.
As a result, the atmosphere is destabilizing and leading to a
showery regime. Most of the precipitation remains confined to
the coastal zone. Snow levels along the coast rose above 1000
feet this morning, but are falling as colder air moves in. Areas
of light snow are spreading into Bristol Bay ahead of the upper
center, but with little accumulation. Otherwise, quiet conditions
prevail across the remainder of Southwest Alaska and westward
into the eastern Bering Sea, under the influence of an upper
level ridge. Further west, a deep low is approaching the central
Aleutians, with gale force winds and precipitation spreading
northward across the chain. The airmass was cold enough to support
snow at the onset, but temperatures are gradually warming and
leading to a transition to mixed precipitation.

&&

.MODEL DISCUSSION...

As the storm system in the east winds down, the focus shifts to
the low along the Aleutians. Over the last 48 hours the models
have shifted much farther north with the track of the low. Based
on the 12Z and 18Z model runs they do now seem to be stabilizing
with the track of the low. Thus, expect only minor adjustments to
the forecast for the Bering Sea and Aleutians from here on out. A
trough digging south to the west of this low will interact with
another storm crossing the North Pacific on Saturday night. All
solutions ultimately merge the new low and old low along the
Alaska Peninsula. However, this is a very dynamic situation and
timing of interacting features will be key. Bottom line though, a
large and deep storm system will affect southern Alaska Sunday
through Monday.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

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

A vertically stacked low with cold air at 500mb around -33 degrees
Celsius will bring showery conditions tonight from Kodiak Island
north into the Kenai Peninsula to near Anchorage and the Matanuska
valley. The Hi-Res models have not been showing any precipitation
moving into the lee side of the Chugach and Kenai Mountains, but
unstable air with Total Totals of 55 or better may produce a few
rain and snow showers around Anchorage, the Matanuska Valley, and western
Kenai Peninsula through this evening. This low will move east
into Bristol Bay by Saturday morning with most of the showers
ending across the area. Onshore flow will continue along the
eastern Kenai Peninsula keeping precipitation going through
Saturday. On Sunday morning the next system in the form of a warm
front moves into the southwestern Gulf and Kodiak Island bringing
a quick shot of snow to Kodiak Island before changing to rain by
the afternoon. This system will occlude over the Gulf on Sunday
and push into the Kenai Peninsula and coastal areas of Prince
William Sound by Sunday afternoon and evening. Most of the
precipitation will begin as snow and then change over to rain
along coastal areas during the day on Monday as warmer air advects
northward. This system will bring another round of snow to the
higher elevations of the eastern Kenai Peninsula and western
Prince William Sound as well as the higher elevations near
Cordova. It is too early to say how much snowfall will occur but
it will likely be less than this week's storm. Please check the
weather at weather.gov/afc and avalanche forecasts from Chugach
National Forest Avalanche Information Center at cnfaic.org if you
plan to be recreating in the mountains.

&&

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

A low currently over the western Gulf has brought rain and snow
showers to the Interior Bristol Bay area today. These showers will
gradually diminish overnight as the low moves inland and weakens.
The next low to impact Southwestern Alaska will move near the
Shumagin Islands and west of Kodiak Island Sunday morning. Expect
a mix of rain and snow over the Alaska Peninsula (AKPen) and
mostly snow for the Bristol Bay area as moist, southerly flow
advects into the area. One to two inches is expected through
Monday morning. Snow may reach as far north as Bethel Sunday night
to Monday morning. Chances are looking a little more likely
Sunday night into Monday, although the probability extent drops
north of Bethel.

In addition, strong southerly winds are expected through the gaps
of AKPen and Bristol Bay interior Sun afternoon through the
overnight into Monday. Models are hinting at a brief period of
especially high gusts in the interior Bristol Bay area to upwards
of 70 to 80 kts with winds at 850 mb mixing down due to the
nature of gap winds. Enough uncertainty exists however and we will
continue to watch as the low tracks east. Also, high end gales,
with storm force gusts are expected over the waters in Bristol
Bay and west of Akhiok. Possible threat locations from peak gap
winds will depend on not just the position, but also the
orientation of the trough as it passes the Shumagin Islands.
Bethel can expect up to sustained winds of 25 mph. Higher winds
are expected along the entire southwest coastline and Nunivak
Island Sunday night and Monday.

&&

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

A Winter Storm Watch continues for the Pribilof Islands and the
Eastern Aleutians.

Low pressure will move into the southern Bering Sea tonight
bringing a swath of moisture across the Central and Eastern
Aleutians. The low has tracked more north and west compared to
models yesterday. Precipitation should remain south of the
Pribilofs until Saturday afternoon when snow is possible for St.
George. Snow chances will begin to increase for St. Paul
overnight Saturday through Sunday night. The best chance for snow
will be Sunday morning. Winds are expected to reach high end gale
force on the north side of the low with storm force gusts. On
Sunday, winds may gust up to 50 mph and any snow that occurs will
reduce visibility significantly. Sea ice is currently located
between St Paul and St George, thus reduction of friction will
only help to keep winds strong through the forecast period.

A similar situation is expected to occur for Unalaska and the
Eastern Aleutians as the low shifts east. Small details decrease
certainty in regards to precipitation type transitions and the
speed of the low as it tracks towards the Shumagin Islands, but
the overall weather pattern is expected to remain. Warm air is
expected to move into the southern Bering with the low. The
Eastern Aleutians will start off as snow Saturday morning and
gradually transition to all rain by Saturday afternoon. A high
amplitude ridge to the west will increase the pressure gradient as
this low begins to stall and thus ramp up northerly winds further
throughout the Bering. The timing of the transition back to snow
is also still a little uncertain. While cold, northerly air may
assist in transitioning precipitation back to snow, 850 mb
temperature advection is fairly weak. There may also still be
enough energy and forcing to help turn over to snow.

Consequential to the northwest extent of the low in the southern
Bering, the south Kamchatka low expected to reach the western
Aleutians will be slightly delayed to Sunday after midnight to
Monday morning with gale force winds and another round of rain and
snow.

&&

.Marine (Days 3 through 5: Monday through Wednesday)...

Gulf of Alaska: A weakening low moves across the Southern Gulf
and its front moves to the Northern Gulf for Wednesday. Forecast
confidence decreases. Gales with the front move to form a high end
gale force barrier jet along the North Gulf Coast, and through
Cook Inlet and Shelikof Strait diminish late Monday. Areas of
storm force winds through the Barren Islands and Kamishak Bay for
Monday. Seas to 16 feet with the front through Tuesday, and to 14
feet across the Southern Gulf through Wednesday.

Bering Sea: A weakening low along the Alaska Peninsula moves into
the Gulf, and its front extends over the Southeast Bering through
Tuesday. A strong front stretches from a well developed Kamchatka
low across the Aleutians and Bering through Wednesday. Forecast
confidence decreases. Northerly high end gales over the Central
and Eastern Bering moves across the Alaska Peninsula late Monday.
Seas to 20 feet on the Bering side, subsiding. Freezing spray over
Southern Bering in ice free waters. Widespread high end gales
with the low and front moves to the Central Aleutians and Bering,
diminishing Wednesday. Seas to 20 feet in the Western Bering,
subsiding, but persisting along the Pacific side through
Wednesday.

&&

.Long Term Discussion (Days 4 through 7: Tuesday through
Friday)...

A broad frontal system over the Bering combined with multiple
upper-level troughs later next week will usher snow and
potentially snow/rain mixed and periods of gusty winds over much
of the Aleutians, Bering and Southwest AK. An amplified low
connected to the aforementioned front will move slowly across the
Bering which will aid to spreading increased low clouds and
additional precipitation over the Aleutians and Southwest Delta
Coast. While most models indicate a brief period of gales
offshore Tue morning, the potential for widespread gales is
favorable given the motion and how this pattern will play out, but
will wait for future ECM and GEMR solutions to see whether they
will pick up the winds in comparison to GFS. In fact, GFS is by
far the most aggressive of the rest.

At Southcentral, an upper low over the Gulf will send a few strong
upper waves toward Southcentral but mainly concentrated over
Prince William Sound Tue morning through Wed afternoon.
Precipitation from this event could reach Anchorage Bowl and MatSu
Valleys while the heaviest precipitation is expected east of
Anchorage Bowl. A transient upper ridge will pass through
Southcentral between Wed night and Thu night, and this could
either delay or speed up the arrival of a trailing upper trough
from the eastern Bering. There is uncertainty with the timing of
the latter feature over the Gulf, for this will wait until most if
not all the solutions jump on the same sheet of music for this
next expected feature.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch: 185 195.
MARINE...Gales: 120, 155, 170, 171-177, 179, 412, 413, 414.
         Heavy Freezing Spray: 179.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...SEB
SOUTHCENTRAL ALASKA...RC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...VR
MARINE/LONG TERM...KZ/CB

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
513 AM AKDT Sat Mar 26 2022

AKZ155-271400-
Kuskokwim Delta-
Including the cities of Bethel, Hooper Bay, and Nunivak Island
513 AM AKDT Sat Mar 26 2022

...GUSTY NORTHEAST WINDS EXPECTED WITH POSSIBLE BLOWING SNOW AND
REDUCED VISIBILITIES SUNDAY AFTERNOON THROUGH MONDAY EVENING FOR
THE KUSKOKWIM DELTA...

There is high confidence for gusty northeasterly winds across the
Kuskokwim Delta Sunday afternoon through Monday evening, with
gusts up to 40 mph expected. Whether the Kuskokwim Delta will see
any snow and blowing snow depends on the track of a low pressure
system moving towards the Shumagin Islands from the North Pacific.
The Kuskokwim Delta Coastline will have the best chance of seeing
blowing snow and reduced visibilities, but uncertainty remains.
Stay tuned as we continue to update the forecast.