Blizzard and Winter Storm in Alaska, February 2 to 4, 2022

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

.ANALYSIS AND UPPER LEVELS...

In the upper levels, there is a weak upper level ridge that is
being broken down by an upper level trough moving northeastward.
The axis of this upper level trough was currently south of Kodiak
Island at the time of this writing. At the surface, there is a low
pressure system moving northwestward in the Bering Sea. Its
associated front is bringing wintry precipitation to practically
all of southern Alaska this morning and afternoon. Snow was
falling across much of Southwest Alaska with interior Bristol Bay
(Koliganek and New Stuyahok especially reporting 1/4 to 1/2 mile
visibility as well as moderate to heavy snow for a good portion of
the mid to late morning hours). Winds were also accompanying the
snow in these areas with gusts up to 48 kts for Koliganek and 44
kts at New Stuyahok leading to some blowing snow. Temperatures
were mostly in the upper 20s to near 30 degrees with the snowfall
leading to the snow being more of a wetter consistency but dry
enough to blow around some. Dillingham was also reporting 1/2
mile visibility a majority of the morning, though, with winds not
nearly as strong. A majority of the Kuskokwim Delta was also
reporting 1/2 mile visibilities with moderate to heavy snow with
gusty winds. Bethel had a gust to 30 kts earlier today with the
snow and Toksook Bay gusted to 45 kts.

Light snow was also moving northward along the Kenai Peninsula
with Homer north to the Anchorage Bowl all reporting snow so far
today. Kodiak remained snow for much of the overnight into the
morning today but has since changed over to all rain around 18-19z
earlier today.

Lastly, another low was seen on satellite imagery moving northward
towards the Central Aleutians with storm force winds and increased
seas expected for the coastal waters and even across the Bering
Sea as it continues northward.

&&

.MODEL DISCUSSION...

Models remain in overall good agreement on the synoptic scale
features out through Day 3. The current frontal system impacting
southern Alaska remains on track as well as the storm force low
moving northward from the North Pacific towards the Central
Aleutians and then into the Bering Sea early Wednesday. While the
overall pattern remains in rather good agreement with features
Wednesday afternoon through Friday, there are still differences
that arise in the timing, exact tracks, amount of warm air
associated with the next system to impact the southern Mainland
later this week. Therefore, continued fine tuning for this system
was done for Southwest and Southcentral Alaska. Model guidance
differs on the track of the low that will move into the Gulf of
Alaska Thursday afternoon with the Canadian-NH furthest west south
of Kodiak Island and NAM furthest east closer to the west-central
Gulf. The GFS and EC were more in the middle between the other
two. They also differ on the track of the low behind this one for
Thursday night into Friday southeast of the Eastern Aleutians.
NAM and Canadian-NH were furthest west and while EC and GFS
further east, though, strength is similar.

&&

.AVIATION...

PANC...Light snow is expected at the terminal through around
02/06z this evening when we expect the light snow to start
tapering off. MVFR conditions are most likely but there could be a
period during the late afternoon/early evening where IFR
conditions are possible. Expect a stiff northerly wind through
this evening as well before diminishing overnight but winds are
expected to remain north. VFR conditions are mostly expected
beyond 02/09z tonight through the end of the TAF package.

&&

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

Water vapor imagery shows a shortwave trough moving across
Southcentral this evening with numerous snow showers stretching
from Cook Inlet into Prince William Sound. Over the course of the
evening hours snow showers are expected to diminish in coverage as
a new triple point low takes shape along the Gulf coast and
pushes eastward toward the Panhandle. The net effect of the new
low will result in precipitation dying off over Southcentral as
upper level forcing shifts to the east with the new low. Winter
weather advisories for blowing snow in Thompson Pass and along the
western Kenai Peninsula remain in effect. Periods of light to
moderate snow and winds gusting from 30 to as high as 45 mph,
especially across Thompson Pass, may result in whiteout conditions
at times into tonight. As low pressure exits Southcentral and a
triple point low skirts the Gulf coast into the Panhandle through
the morning hours on Wednesday, northerly outflow winds are
forecast to spill out of the bays and passes in the wake of the
low, especially across the Copper River Delta and through the
Valdez Arm. Wind gusts of 30+ knots can be anticipated.

Temporary ridging of high pressure is then forecast to overspread
Southcentral on Wednesday. Precipitation will take a breather
while diminished winds and few potential breaks in the clouds will
promote a more user friendly day. However,this will all change by
Thursday as the next upper low and associated front move into the
Gulf.

As with today, easterly barrier jet winds are forecast offshore
of the coast with gales potentially spanning from Kayak Island to
the Barren Islands. A second round of snow will also accompany an
arriving front with light snow moving into Southcentral by midday
on Thursday. Some uncertainty exists in the forecast as models
have subtle differences in the smaller scale features, which
result in widely different outcomes as far as placement of snow
and snow amounts. As the front moves onshore and ultimately begins
to weaken, a new North Pacific low is forecast to track into the
Alaska Peninsula sometime late Thursday. This next low may
interact with or overtake the previous front entirely thereby
complicating the forecast further. Temperatures are expected to
remain sufficiently cold inland of the coast and the current
thinking is for another extended period of light snow to impact
Southcentral. However, the duration of the snowfall remains in
question and snowfall totals Thursday into Friday could range from
a couple inches to potentially higher amounts. Regardless of
exact snowfall amounts, of greater certainty will be the
redevelopment of elevated southeast winds to gale force. The
threat for blowing snow across Prince William Sound and the Kenai
Peninsula Thursday into Friday will need to be re-evaluated over
the next 24 hours.

&&

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

A North Pacific low continues to move north across the Bering
while its weakening front extends across the Southwest coast. The
Kuskokwim Delta will continue to experience snow and blowing
snow with additional snow accumulations of up to one inch into
the evening hours. Winds will continue to gust as high as 35 mph
before decreasing tonight. Areas of blowing snow along the
Kuskokwim Delta coast from Toksook Bay to Hooper Bay have been
experiencing reduced visibilities. However, these reductions
should begin to subside when the gusty winds decrease tonight.
Dillingham north and west will see additional snow accumulations
of up to two inches with winds gusting as high as 40 mph. Both of
these areas have a Winter Weather Advisory issued and both will
expire at 9 PM AKST this evening.

Southwest will have a bit of a lull Wednesday before another North
Pacific low will move over the southern portion of the Alaska
Peninsula Wednesday night. This system is very similar to the one
that impacted the area earlier in the week. However, it has less
of a swath of warm air associated with it. Rain is likely to push
south to north along the Alaska Peninsula as far north as King
Salmon. Dillingham will see the potential for freezing rain as
this warm air moves in and interacts with the cold air in place.
Elsewhere across Southwest will remain as all snow, with more
blowing snow possible in the Kuskokwim Delta on Thursday as gusty
winds will continue across the area before diminishing Thursday
night into Friday.

&&

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

A series of North Pacific lows will make its way to the Bering
this week. The first one is pushing 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 east 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. As the aforementioned low moves north,
flow over Shemya and the western Aleutians will turn northerly.
This setup favors a chance for blowing snow to occur until the flow
becomes southerly again to drive warmer air over the area. A
second North Pacific low will move over the southern portion of
the Alaska Peninsula Wednesday night. Areas of gale force winds
and heavy precipitation from Unalaska to Port Heiden by Wednesday
afternoon are expected associated with the aforementioned low.
Warmer air behind the front may allow for areas of rain in lower
elevations, however, higher elevations will remain all snow.
Precipitation will spill into Bristol Bay and travel up the
Southwest coast by Wednesday night and Thursday. Another low will
push towards the Alaska Peninsula Friday and bring another band of
precipitation into the area.

&&

.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 Thompson Pass 155 161.
MARINE...Storm Warning: 173-176 411 413.
         Gale Warning: 119 120 127 130 131 138 139 150 160 165
                       170 172 177 179-181 185 412 414.
         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...KZ/AF