Small Craft Advisory 103, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
616 PM AKST Thu Feb 3 2022

.ANALYSIS AND UPPER LEVELS...

An impressively sprawling front that extends from the Panhandle
all the way to the Kamchatka Peninsula is causing a myriad of
different weather across Southern Alaska this afternoon. For much
of Southcentral, snow is the primary precipitation type. It's
generally light for Anchorage and points north, but Winter Weather
Advisories for heavier amounts of snow continue for both sides of
the Kenai Peninsula and the Copper River Basin. Much gustier winds
in combination with the snow are causing blizzard conditions
through Thompson Pass.

Across Southwest Alaska that same front has quite a bit more
forcing with it, in addition to windy conditions. Blizzard
conditions are ongoing through the Kuskokwim Delta with a Winter
Weather Advisory in place across portions of Bristol Bay.

The front extends across the northern Bering with broad southerly
flow continuing over the southern Bering and Aleutians, the cloud
deck associated with the next North Pacific low is approaching the
Eastern Aleutians. Fortunately this low looks to have far less
impact and will be weaker overall.

&&

.MODEL DISCUSSION...

The models are in decent agreement through Saturday afternoon. A
large North Pacific low is expected to enter the Gulf starting
Saturday morning. It will lift north to near Middleton Island
Saturday night, after which point there is some model discrepancy
on how far north the moisture makes it, and precipitation type
near the coast near Cordova. Confidence is increasing that the
Cook Inlet region and Kodiak will be spared from the worst the
storm has to offer, with the Kenai Peninsula and Seward Highway
just getting a glancing blow from the storm. The finer details of
snowfall intensity and amounts both for the current storm and the
upcoming ones remain uncertain, especially with large deviations
in track from model run to model run.

Previous model runs took the storm track significantly further
west, resulting in the possibility of more snow for the Anchorage
area and the Kenai Peninsula. However, the agreement currently is
quite good, but run-to-run consistency remains an issue.

&&

.AVIATION...
PANC...IFR conditions continue over the Anchorage Bowl as steady
light snow has moved into the area. The snow is expected to
persist into the overnight as winds diminish by Friday morning. A
slow tapering of the snow is expected through the day on Friday.
Saturday is expected to be quiet.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Tonight
through Sunday)...

The active pattern continues through this weekend, with several
rounds of snow (and rain in coastal locations) set to impact
Southcentral. This evening, snow continues for the Cook Inlet
region, generally trending weaker through tomorrow morning as an
upper-level shortwave tracks eastward into the Copper River Basin.
Snow will wind down south to north, most likely gradually over
the western Kenai Peninsula, while the Anchorage area should see a
break this evening before another round of light snow returns on
low-level westerly upslope flow overnight. Broadly speaking, 1 to
2 inches of additional snow accumulation can be expected through
Friday morning. For the Copper Basin, 3 to 6 inches of snow can be
expected with colder temperatures present producing a drier,
fluffier snow. Gap winds will also begin to diminish tonight as a
surface low pressure east of Kodiak Island exits into the eastern
Gulf.

A weaker, elongated upper-level disturbance lifts across
Southcentral Friday night, bringing another round of snow,
particularly for the coastal mountains and western Susitna Valley
as strong southeasterly flow in the low-levels keeps the Anchorage
Bowl downsloped out. Significant snowfall accumulations,
especially in higher terrain near Valdez and Cordova look possible
as moist southerly flow sticks around. The Cook Inlet region looks
to clear out as weak ridging sets up Saturday night.

Finally, a stronger system takes aim at Southcentral by Sunday
morning. A North Pacific low will drive north into the Gulf,
bringing yet another round of active weather. Although the track
of the low is presently uncertain, current guidance indicates
that it could produce significant snowfall totals for the coastal
mountains around Valdez and Cordova. Cordova itself is likely to
see wind in combination with falling precipitation, which could
lead to reduced visibilities from blowing snow. However, how much
of this precipitation falls as snow versus rain is uncertain at
this time, as temperatures are expected to hover near the mid-30s
throughout the bulk of the event.

&&

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

Blizzard conditions are occurring along the immediate Kuskokwim
Delta coast and are expected to continue through tonight. Gusty
winds will reach 35 to 40 mph, with gusts as high as 50 mph,
especially along the immediate coast from Toksook Bay to Hooper
Bay. Conditions should begin to improve from south to north by
late tonight as the front exits to the northwest. Additionally,
snowfall has been spilling into the Kuskokwim Valley and will
persist through tonight. A Blizzard Warning remains in effect
until 1 AM AKST Friday for the Kuskokwim Delta coast.

Rain over eastern portions of Bristol Bay has started to switch
back to snow as colder air is moving back into the area. Rain is
still falling southeast of Egegik and Port Heiden, but from King
Salmon north, rain has already switched back to snow.
Precipitation will begin to taper off from west to east through
late this evening. A Winter Weather Advisory remains in effect
for snow and blowing snow, especially Dillingham north and east,
until 6 PM AKST this evening.

A North Pacific low will move east-northeast south of the
Aleutians and crosses over the southern Alaska Peninsula and into
Bristol Bay by Friday night. As the aforementioned low is
tracking northeast, it is weakening and therefore will not be a
major snow maker for Southwest Alaska. Precipitation is expected
over the eastern Aleutians and the southern Alaska Peninsula with
another round of snow likely from Dillingham to New Stuyahok (as
well as surrounding areas) Friday night. Significant snow
accumulations are not expected for these areas, with accumulations
around 1-3 inches possible.

Cold temperatures will return to Southwest Alaska as a trough
located over northern mainland Alaska begins to drop down over the
area Saturday night into Sunday. Wind chills over the Kuskokwim
Delta could drop to -25 degrees or more in the coming week as a
result.

&&

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

Widespread gale force winds are expected to persist through late
tonight along the northern Bering and Southwest coast from Cape
Newenham to Hooper Bay. Additionally, areas of small craft winds
north and south of the Alaska Peninsula and near the Western
Aleutians, will persist into tonight. A North Pacific low will
track over the southern Alaska Peninsula and into Bristol Bay by
Friday night. Winds near the Alaska Peninsula and eastern Aleutians will
ramp up to gale force by Friday and continue to move on the
southeastern edge of the aforementioned low as it tracks into
Bristol Bay. Periods of moderate to heavy rainfall, with possible
snow mixed in, are expected in the eastern Aleutians and southern
Alaska Peninsula by early Friday morning and will last into the
evening hours. Heaviest precipitation is expected along the higher
elevations and should remain all snow. Conditions over much of the
Bering and Aleutians will return to relatively mild conditions
late Saturday into Sunday.

&&

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

Gulf of Alaska: A well developed North Pacific low sweeps 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 moves over the Gulf becoming
Westerly and diminishing Monday. Areas of Easterly storm force
barrier jets develop along the North Gulf Coast on Sunday. Seas to
22 feet, subsiding.

Bering Sea: A well developed Western Aleutian low 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 over
the Western Bering, diminishing to gusty winds Monday. Seas to 14
feet, subsiding. 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 begins 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, 155.
         Winter Weather Advisory: 141.

MARINE...Gale Warning: 120, 127, 130, 132, 150, 155, 172, 185,
                       351, 352.
Heavy Freezing Spray Warning: 185.

FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...JW
SOUTHCENTRAL ALASKA...CQ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS
MARINE/LONG TERM...MK/CB