Gale Warning 348, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
458 PM AKDT Sun Mar 31 2024

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

This morning's precipitation that began overnight has moved out
of most of the area. Portions of the Susitna Valley, the Mat-Su
Valley and Copper River Basin continue to experience light snow
falling. This snow will subside through the evening hours. A
winter weather advisory remains in effect for the Susitna Valley
into 9 pm this evening. Also, breezy conditions in the Copper
River Basin will subside through the evening hours.

Current satellite shows another low pressure near Kodiak Island
moving north northeastward. It is bringing precipitation to
Kodiak Island and will bring precipitation and breezy winds to
the Kenai Peninsula, Mat-Su Valley, the Copper River Basin and
Prince William Sound the next 24 to 48 hours. As it moves up the
coast bringing southeasterly winds, they will switch to
northwesterly in its wake from Kodiak Island to Prince William
Sound. Cold air is already in place resulting in snow as the main
precipitation type in higher elevation and interior locations. A
rain/snow mix is possible at sea level. Areas along the coast
with upslope winds though should expect to receive higher snowfall
amounts. A special weather statement has been issued for snowfall
along the Turnagain Arm and Kenai Peninsula. Wind gusts from the
northwest will be strong through the gaps especially in Shelikof
Strait Monday night into Tuesday morning. Blowing snow is also
possible Monday night into Tuesday morning on western areas of the
Kenai Peninsula and Kodiak Island. Cooler temperatures can be
expected through mid-week with this dominant northwest flow
resulting in lows dropping into the teens and twenties with highs
in the 30s.

-DJ

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA, the BERING SEA and the
ALEUTIANS (Days 1 through 3: Tonight through Wednesday evening)...

A strong upper-level wave continues to drop out of the Arctic and
over the eastern Bering Sea and mainland Southwest Alaska. Bands
of snow showers and blowing snow are occurring over the Kuskokwim
Delta Coast where half-mile visibility or less has been noted
over Nunivak Island and Toksook Bay this afternoon. A Winter
Weather Advisory has been issued for the Kuskokwim Delta Coast
through Monday morning to address this. Temperatures will continue
to drop as the Arctic air settles in over mainland Southwest and
the Alaska Peninsula (AKPEN). Overnight lows will drop into the
negative single-digits to single-digits above zero for the
mainland while the AKPEN sees teens. Day-time highs for Monday
will range from the single-digits above zero to teens for mainland
Southwest with the AKPEN seeing twenties. Expect about the same
overnight lows for Monday night as tonight. Any lingering snow
shower activity will taper off through Monday evening.

The next front moves eastward through the Bering and makes it to
the Pribilof Islands by Monday evening. With cold air already in
place, expect precipitation to start off as snow. Snow combined
with gusty winds looks to reduce visibilities to one-half mile or
less at times. Thus, a Winter Weather Advisory has been issued to
the Pribilofs for Monday evening into the overnight hours. A
transition to rain is anticipated overnight Monday into early
Tuesday morning as warm air works in from the south.

The next big feature of note will be a strong North Pacific low
that will send its front eastward; first with the Western
Aleutians/Western Bering Sea Monday afternoon. This front makes it
to the coast of mainland Southwest by Tuesday afternoon. Expect
mostly rain along the Aleutian Chain and southern AKPEN with this
system. With cold air already in place over the Kuskokwim Delta
and a good portion of Bristol Bay, expect precipitation to start
as snow there Tuesday afternoon. The pressure gradient will be
tight with high pressure over the mainland and the strong low in
the Western Bering. Thus, there is another chance for more blowing
snow for the Kuskokwim Delta coast and northern Bristol Bay coast
Tuesday afternoon as precipitation starts. Warm air works in from
the Bering Tuesday evening with a change to rain/snow mix and
rain.

Perhaps the bigger story with this system will be its wind
field. Confidence continues to increase that the low will take a
more northerly track while straddling the western Bering Sea. This
is a favorable track for the western Aleutians to receive the
southern core of winds around the low. A small corridor of
sustained hurricane force-winds are looking likely for the for the
western Aleutian marine zones and possibly over Shemya. Wide-
spread hurricane-force gusts are also likely for the marine zones
of the Western Bering. As such, a High Wind Watch has been issued
for the Western Aleutians early Tuesday morning through Tuesday
evening. The peak of highest winds looks to occur mid-day Tuesday
through late Tuesday afternoon before winds slowly begin to
diminish.

Yet another system, though weaker, looks to approach the mainland
Southwest Coast for Wednesday evening. Right now, this system
looks to begin as rain and potentially transition over to snow
Wednesday night.

-DAN

&&

.LONG TERM FORECAST (Days 4 through 7)...

Upper level ridging moves over southern Alaska by mid week and
will continue tracking eastward through the end of the week.
Longwave troughing moves in behind the ridge, tracking across the
Bering Sea towards Southwest Alaska by Friday. Another quick
transient ridge moves west to east ahead of a North Pacific low
pushing into the western Bering next weekend. There is still quite
a bit of model discrepancy regarding how quickly this low tracks,
with the GFS being the quickest and tracking over the Alaska
Peninsula towards the southern Gulf by Saturday afternoon. The
overall track and strength is in decent agreement amongst the
models, with a 7-10mb spread between them. This pattern is
conducive to areas of heavy precipitation along the Aleutian
Islands and gusty southerly winds across the Eastern Aleutians
and southern Alaska Peninsula. Some of the models are hinting at
the potential for storm force gusts along the Central Aleutians
Friday night into Saturday; this potential will continue to be
monitored through this week. As the low passes the southern AKPen,
guidance looks to pull colder air out of the north across the
Bering Sea and across the Eastern Aleutians/AKPen. This could
result in a round of gusty northerly winds for the aforementioned
areas.

&&

.AVIATION...

PANC...VFR conditions will persist while winds continue to lighten
through the evening. Winds will turn from the north overnight,
while ceilings begin to lower through the morning hours. Snow
looks to return for the late morning bringing ceilings back into
the MVFR range.

MTL

&&

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
1021 PM AKDT Sun Mar 31 2024

AKZ132-135-020000-
Northeast Prince William Sound-Southeast Prince William Sound-
Including the cities of Valdez, Thompson Pass, and Cordova
1021 PM AKDT Sun Mar 31 2024

...BANDS OF MODERATE TO HEAVY SNOW SHOWERS ALONG THE COAST OF
PRINCE WILLIAM SOUND THROUGH MONDAY...

Widespread snow showers will develop tonight and continue through
Monday across the Prince William Sound. 6 to 12 inches of snow is
possible from Valdez to Cordova with the highest amounts likely
in Cordova and through Thompson Pass. Snowfall rates may reach one
to two inches per hour at times in heavier snow showers, reducing
visibility to one half mile or less. Snowfall on wet roads may
lead to icy conditions as overnight temperatures fall below
freezing. Snowfall on area roads may turn slushy by Monday
afternoon as temperatures warm back into the mid 30s.