NWS Anchorage, AK wrote its last area forecast discussion before the first event at Feb 10, 5:49 AM AKST, 8 hours 58 minutes earlier.
Area forecast discussion, Feb 10, 5:49 AM AKST, 8 hours 58 minutes before
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
549 AM AKST Thu Feb 10 2022
.ANALYSIS AND UPPER LEVELS...
The upper-level low that has been nearly stationary over Hooper
Bay for the past few days has finally started to shift eastward,
and it is moving slowly east through the interior. The associated
cold airmass over Southwest and most of the Bering and Aleutian
Chain is gradually retreating to the northeast with the movement
of the low. In the wake of this low, a shortwave ridge of high
pressure is building across the Gulf and shifting eastward across
Southcentral. This is providing a brief period of cold and quiet
weather for the region until the next system arrives on Friday.
Deep southerly flow is transporting moisture and warmer air into
the Gulf.
Out west, a broad longwave trough with multiple low centers is
dominating the North Pacific, Aleutians and Bering Sea. The
primary low is currently tracking northward near Adak and into the
southern Bering. The associated front is sweeping northward
across the Aleutian Chain and into the Bering, and it is also
pushing towards Southwest. A Blizzard Warning remains in effect
today for the Pribilof Islands as gusty northeasterly winds could
lead to blowing snow and significantly reduced visibility. A
secondary low within the complex is still located over the North
Pacific, but it is tracking northward towards the Aleutians.
&&
.MODEL DISCUSSION...
Models have come into much better agreement regarding the
evolution of the complex low with multiple centers. All models
depict the primary low that is currently moving into the Bering to
track westward to Shemya through Saturday. The models also
generally agree that another North Pacific low will move
northward over the eastern Bering by Friday evening. In regards
to the low signature that forms near the western Gulf coast, the
models are now hinting that the feature will form much later in
time, however Shelikof Strait and the usual gaps and passes are
still expected to experience strong winds this evening into
Friday. Model agreement remains moderate in regards to the track
and strength of the North Pacific low that moves over the western
Aleutians early Friday morning.
&&
.AVIATION...
PANC...VFR conditions are expected to persist through the TAF
period. Gusty southerly winds will diminish and give way to light
northerly winds this afternoon as the next system approaches.
Light snow over the terminal is expected to begin around midnight
tonight along with an increase in northerly winds.
&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Saturday night)...
Cyclonic flow aloft on the south side of a deep upper level low
over Interior Alaska will combine with continued strong low level
south to southwest to produce some light snow along the south to
west facing slopes of area mountain ranges. Otherwise, expect a
cold and dry day across Southcentral. Gusty surface winds present
across parts of Southcentral this morning will gradually diminish
today as the deep cold air mass which moved in last night
retreats northward with the upper low.
An upper level short-wave ridge oriented east-west from the Gulf
of Alaska to eastern Bering Sea this morning will lift northward
through tonight, once again opening southern Alaska up to the
long-wave trough sitting over the North Pacific. A strong jet
stream will transport a plethora of short-waves northward across
the Gulf this afternoon and to Southcentral tonight, bringing
widespread clouds and snow back into the region. None of these
short-waves look particularly strong, so snowfall will be light.
Meanwhile, an east-west oriented warm front will lift northward
toward Kodiak Island, pushing up against the deep arctic airmass
in place. The strong thermal and pressure gradients will lead to
gale to storm force winds across much of the Gulf coastal waters
tonight through Friday morning. The airmass will be cold enough
to support snow as precipitation first reaches Kodiak Island late
this afternoon or evening, but as the warm front passes through
overnight, snow will gradually change to rain. There could be
some localized areas of blowing snow this evening. However, the
strong winds accompanying the precipitation will cause surface
temperatures to rise fairly quickly, which should limit the
amount of blowing snow.
The warm front will dissipate along the north Gulf coast Friday
as the parent low tracks into the Bering Sea. Don't expect a big
warm-up for Southcentral, but communities along the Gulf coast,
namely Cordova, will warm enough to change to rain by Friday
afternoon. After the initial bout of light snow over interior
Southcentral tonight, it looks like a break in upper waves until
Friday night. While there is some uncertainty, it looks favorable
for a series of stronger upper level short-waves to lift
northward across Southcentral Friday night through Saturday,
bringing widespread accumulating snow to most of the region.
It's too early to nail down specific snow accumulation, but
there is potential for widespread amounts in the 3 to 6 inch
range, depending on the exact track and strength of each
individual short-wave. Snow could linger through the weekend as
cyclonic flow persists aloft, with the likelihood of additional
short-waves moving through.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
An unsettled weather pattern is expected over the next couple of
days as a warm front bring snow to the area. The snow will move
from south to north across the area and will begin this evening
and continue through Friday evening. The heaviest snow is expected
from this evening through the mid-morning hours on Friday across
Bristol Bay. The heaviest snow will be in the 3-6" range and is
expected across central Bristol Bay including Dillingham. A Winter
Weather Advisory has been issued for blowing snow as strong winds
will reduce visibility to one half mile at times for areas
northwest of King Salmon. The snow will then taper off from south
to north Friday night into Saturday morning. The remainder of the
period will be cloudy and cold with occasional snow showers.
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
A storm system is currently moving northward from the North
Pacific into the central Bering Sea. The storm is projected to
move westward along the Aleutian Chain due to a dome of cold air
to the east which provides ample resistance for eastward motion.
A Blizzard Warning remains in effect for the Pribilof Islands
until 1am Thursday night due to the combination of snow and strong
winds expected to reduce visibility to one quarter mile or less at
times. The snow will taper off tonight across the Pribilof
Islands. Other than snow in the Pribilof Islands, this low will
also bring widespread gale force winds to the central and western
Bering Sea through early Saturday morning. Large 20ft long period
swell associated with these winds through early Saturday morning
across the western and central Bering Sea.
&&
.Marine (Days 3 through 5: Saturday through Monday)...
Gulf of Alaska:
A North Gulf Coast low moves inland and dissipates for Sunday.
Gusty Southwest winds over the Gulf diminish Sunday. Seas to 12
feet subsiding. A second low moves across the Southern Gulf with
gusty Northwest winds through Monday. A new low and front approach
the Southwest Gulf with increasing Southwest winds for Monday.
Bering Sea/Aleutians:
High pressure moves into the Eastern Bering for Monday. Forecast
confidence uncertain with approaching North Pacific low. The
Aleutian low complex merges with the approaching low. Widespread
Easterly Gusty winds with areas of Central Aleutian gales increase
to become widespread high end gales with areas of storm force
winds ahead of the front moving over the Aleutians and Bering.
Seas to 20 feet extend across the Aleutians into the Bering
through Monday. There is a risk of freezing spray over Western
Bering open waters.
&&
.Long Term Discussion (Days 4 through 7: Sunday through Wednesday)...
The first couple days of the long term period (Sunday through
Tuesday) remain in fairly good agreement on the large scale upper
level pattern across Southern Alaska. Models depict a strong North
Pacific ridge remaining anchored in place during this time frame
with brief extensions of it northward into the Bering Sea and
Southern Alaska. They also keep an upper level trough anchored
across the North Slope and the Northwest Territories during this
time frame. Another stronger and closed off upper level low
remains in place south of the Western Aleutians. Basically, expect
occasional systems of various strength and size to move up and
over this ridge breaking it down some from time to time. This will
result in occasional rain/snow for Southcentral with any rain
mostly being confined to the coastal areas and Kodiak Island where
warm air will more easily move in. For Tuesday night through
Wednesday, model guidance starts to spread out on how the upper
level pattern will evolve with the EC being most robust with the
upper level trough over the North Slope extending southward
especially across Southcentral Alaska. The Canadian-NH and the GFS
remain more modest with this keeping the overall pattern earlier
on in the period in place with periodic rounds of precipitation.
Overall, models keep temperatures in the normal to slightly above
normal area during this time frame.
&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch: 195 (Pribilof Islands).
MARINE...Storm Warning: 130, 131, 138.
Gale Warning: 119, 120, 132, 136, 137, 139, 150, 155, 160,
165, 175-180, 351, 352, 411-414.
Heavy Freezing Spray: 139, 179, 185, 412, 414.
FIRE WEATHER...NONE.
&&
SYNOPSIS AND MODEL DISCUSSION...AF
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ED
MARINE/LONG TERM...KZ/MV