Valdez, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

656
FXAK68 PAFC 031436
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
536 AM AKST Tue Dec 3 2024

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

Key Points:

* Winter Weather Advisory for freezing rain for Anchorage, Western
  Kenai Peninsula, Susitna Valley, and the Matanuska Valley
  Tuesday into Wednesday

* Winter Weather Advisory for blowing snow for Thompson Pass from
  noon Tuesday until midnight Tuesday night

* Strong winds and heavy precipitation along Southcentral coast,
  with gale to locally storm-force winds in the northern Gulf,
  Cook Inlet, and Shelikof Strait through Wednesday

Discussion:

Southerly upper-level flow with multiple shortwaves and lows
embedded within it continues into Southcentral, keeping the
weather pattern active and bringing more strong winds and
precipitation mainly along the coast. The next strong low
continues north-northwestward through the Gulf towards Kodiak
Island this morning through tonight. Winds in the northern Gulf
are beginning to pick up this morning and will continue to
strengthen throughout the day today with a barrier jet producing a
large area of gale-force winds along the northern Gulf coast as
well as additional pockets of gale-force winds returning to Cook
Inlet and Shelikof Strait through Tuesday night. Winds may
approach storm-force, especially near the Barren Islands. Ahead
of the approaching front, very light upslope precipitation is
possible along the Southcentral coast during the day today, but
will become steadier and heavy at times by this evening as the
front approaches the coast. Steady upslope precipitation, in the
form of rain at sea level, will continue through at least
Wednesday as reinforcing waves stream up from the south.

Typical downsloping areas should remain mostly dry throughout the
period, although the initial push of precipitation coincident
with upper level shortwaves this afternoon into this evening may
bring light precipitation to the western Kenai Peninsula and
Anchorage before the strongest downsloping begins. With warmer air
moving in aloft and surface temperatures remaining below
freezing, light freezing rain is expected across these areas, as
well as the in the Susitna Valley and western Matanuska Valley.

As such, a Winter Weather Advisory for a glaze of freezing rain
is in effect for Anchorage, the western Kenai Peninsula, and the
western Matanuska Valley from this morning through early Wednesday
morning. An additional Winter Weather Advisory for the Susitna
Valley will be in effect from this afternoon through Wednesday
night where colder air is expected to hang on longer, resulting in
ice accumulations of up to one tenth of an inch. Surface
temperatures are expected to rise above freezing Tuesday night
into Wednesday morning across the western Kenai and Anchorage, but
rain can still freeze when hitting cold road and sidewalk
surfaces given the very cold conditions over the past several
days.

With colder temperatures still in place in the Copper River
Basin, cold air will continue to drain through Thompson Pass and
promote the continuation of strong northerly winds. As
precipitation moves in from the south, snow will begin in the Pass
with snow levels initially near 1500 ft Tuesday afternoon,
promoting blowing snow and reduced visibility. A Winter Weather
Advisory is in effect for Thompson Pass starting 12 PM Tuesday
with the blowing snow threat ending by midnight Tuesday night as
the winds turn southerly with the front pushing inland.

-JH

&&



.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3)...

MAIN POINTS:

* Winter Weather Advisories for freezing rain are in effect
  through Wednesday evening / Thursday afternoon across Southwest
  Alaska.

* Warmer air moves into Southwest Alaska this evening through
  tomorrow afternoon.

* Periods of rain and snow showers continue through today in the
  Aleutians.

Freezing drizzle and snow continues to fall across the Southwest
this morning as temperatures struggle to rise and stay above
freezing from Iliamna to Naknek northward. The culprit is
northerly to northeasterly wind flow keeping cool air trapped at
the surface as warmer air moves overhead. Through the day, warm
air will slowly increase its coverage over the area. Increased
precipitation is expected this evening into tomorrow as a low
moves across the Alaska Peninsula and into Bristol Bay. Its
associated warm front moving over the Alaska Peninsula and
portions of Southwest Alaska brings this stronger push of warmer
air. Simultaneously, precipitation chances of a mix of freezing
rain/snow/rain are expected to increase late this evening into
tomorrow afternoon. A trace to a few hundredths of an inch of ice
accumulation is possible this evening into early tomorrow morning
from Dillingham north to Koliganek with the Lower Kuskokwim Valley
seeing precipitation begin in the mid-morning hours of tomorrow.
With colder air in place, most areas from Kipnuk through Bethel to
Sleetmute should see a greater chance for mainly snow from this
evening into tomorrow afternoon; though a late-day brief period of
sleet/freezing drizzle can`t be ruled out. Wind gusts up to 40
mph along the Alaska Peninsula and Bristol Bay coastlines are
likely through late tomorrow morning.

Elsewhere, scattered rain and snow showers are likely in the
Aleutians as a low moves south across Adak through Wednesday
evening. Northerly to northwesterly wind gusts as high as 40 mph
are likely from this evening into tomorrow afternoon from Nikolski
to False Pass. A second low will form just south of Dutch Harbor
bringing warmer air and rain showers tomorrow night into Thursday
afternoon from Dutch Harbor east to the Alaska Peninsula.

-DJ

&&

.LONG TERM FORECAST (Days 4 through 7: Friday through Monday)...

On the Alaska Weather map, a Southeast Alaskan/Western Canadian
ridge holds its place across the Interior Mainland through the
forecast period. To the West, a more chaotic situation is in place
as a broad area of low centers and shortwave troughs wobble
around the Bering. Forecast uncertainty is considerable, but
decreases through the weekend as ensemble blends carry the
forecast load. The unsettled start smooths out to a single
extended trough across the Aleutians and Bering into the North
Pacific by Sunday. This trough edges into the Gulf of Alaska for
the beginning of the week. In the meantime, surface low centers,
fronts and troughs bring a warmer and wetter pattern with
widespread gusty winds and mixed precipitation across the Southern
half of the state through the weekend. Coastal locations receive
locally moderate rain over the Central and Eastern Aleutians and
Southwest Alaska into the Alaska Peninsula, Kodiak Island into
Cook Inlet and across Southcentral Alaska. Temperatures inland
should remain cool enough to support snow, with areas of mixed or
freezing precipitation in between away from the coasts.

&&

.AVIATION...

PANC...VFR conditions are expected to continue through about 18Z,
after which point a lifting front increases precipitation chances.
With below freezing surface temperatures and above freezing air
aloft, there is a chance for a period of a wintry mix or light
freezing rain/drizzle late Tuesday morning into the afternoon
hours. Downsloping is expected to limit the precipitation, but
could see on-again off-again showers through Wed morning. Ceilings
are likely to remain VFR, though could drop below 5000 ft at
times, with a low chance of a brief period at MVFR.

Light northeasterly winds increase through the day, becoming
northerly and potentially gusting as high as 25 knots by this
afternoon. Precipitation chances decrease markedly beyond 09Z,
with winds also becoming light for much of Wednesday. There is a
small chance for southeasterly Turnagain Arm winds to affect the
terminal beginning late Wednesday morning, with wind shear a more
likely concern if winds remain light near the surface.

Quesada

&&


$$