982
FXAK68 PAFC 250458
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
758 PM AKST Sun Nov 24 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
3: This afternoon through Wednesday afternoon)...

Overall, the near-term forecast remains largely unchanged, but
there is still minor uncertainty with forecast snow amounts.
Confidence is high that the Mat-Su Valleys will see about 4-9
inches of snow from tonight through tomorrow morning, for which
Winter Weather Advisories are in effect. 5-6 inches of snowfall
are also forecast for the Anchorage Hillside, with lower amounts
(about 1-3 inches) forecast for elsewhere across Southcentral.

Competing factors are leading to lower confidence in snow amounts
for the Anchorage Bowl, with a chance that snow amounts could lean
a little lower in the 1-3 inch range. As mentioned in the
previous discussion, snow amounts will depend on how long it takes
our rather dry atmosphere to saturate (including how saturated
the dendritic growth zone will be), and whether or not a trailing
shortwave could lead to both longer and higher intensity snowfall.
Furthermore, uncertainties with the placement of a weak lee-side
low could affect low level flow. If up-Inlet winds and
southeasterly Turnagain Arm winds are stronger than currently
forecast, a convergence zone setting up along Anchorage could
enhance snow amounts. At the same time, the influx of warmer air
will probably lead to an even denser and heavier snow, or even
potentially allow some rain to mix in. Overall, while there`s some
minor uncertainty in the forecast for the Anchorage Bowl, the
general picture likely won`t deviate from what`s currently
depicted in the forecast: a couple inches of wetter snow between
tonight and late Monday morning.

By Tuesday morning, precipitation should taper off for all but
over higher terrain. An additional shortwave dropping south over
Southcentral from the northwest Arctic will reinforce more cold
air, dropping temperatures well below normal once again. Overnight
lows will drop into the single digits and negatives again by
Tuesday night. Strong winds are once again likely to develop
through Seward, Whittier and Thompson Pass, and may develop in the
Mat Valley and Valdez depending on the path of the upper level
feature. This could bring the possibility of blowing snow,
especially at higher elevations (including Thompson Pass) where
colder temperatures will keep tonight and tomorrow`s snow less
dense and more transportable. Otherwise, expect clear and cold
weather to return by mid-week, with little to no chance of
precipitation.

-CJ/Chen

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (Days 1 through 3: Today through Wednesday)...

An area of low pressure off the coast of Alaska between Nunivak
Island and St. Lawrence Island continues to push eastward and
inland this evening. The frontal system and its precipitation, now
mainly in the form of snow across the the Lower Kuskokwim Valley,
will continue to push east towards the Alaska Range. Farther
south along the Bristol Bay coast where precipitation is mainly
rain, a brief period of freezing drizzle is possible tonight,
particularly between Dillingham and Iliamna, as dry air aloft
moves in behind the front with lingering low level moisture. This
system starts to impact Southcentral Alaska for Monday, while snow
showers along the Western Alaska Range continue with upslope
westerly to northwesterly flow behind it. Northerly to northwest
flow for Southwest Alaska Monday through Wednesday will lead lead
to colder and drier conditions across the area.

Farther west, a shortwave ridge over the western Aleutians will
shift northward into the Bering Sea, while a North Pacific low
pushes its front northwest toward the Western and Central
Aleutians by this evening. Steady rain is expected in these areas
tonight through Monday. By Tuesday morning, the low is forecast to
move north near the Central Aleutians, bringing another round of
steady rain. The Eastern Aleutians are also likely to see
persistent showers through Tuesday, with some rain reaching the
southern Alaska Peninsula by Tuesday afternoon. However,
uncertainty remains regarding how far north the North Pacific low
and its associated moisture will track and develop beyond Tuesday
afternoon. However, there is still a chance for steady rain to
reach the Pribilof Islands and southern AKPEN late Tuesday into
Wednesday.

-ME

&&

.LONG TERM FORECAST (Days 4 through 7: Thursday through Sunday)...

For mainland Alaska, a period of relative calm remain a mainstay.
Thursday and Friday continue to see clear skies and cold
temperatures as high pressure stretches from the Bering Strait,
southeast through Kodiak, ushering cold and dry Arctic air. Out
west and in the Bering Sea, a decaying front will stall as it
slams against the high pressure over mainland on Thursday,
eventually losing steam and fizzling out. A large upper level low
will slowly move east from the northwestern Pacific on Friday,
starting to pinch the high pressure in the Gulf of Alaska. Warm
and moist southerly winds will start to bring clouds and warmer
conditions in from the pacific, ending the clear skies
everywhere. As this low moves east, it will struggle to displace
the well entrenched high pressure and will dramatically slow. By
the weekend, areas along the Gulf coast should see precipitation
return. All other inland areas will continue to remain dry,
keeping the well below normal precipitation trends intact.


&&
.AVIATION...

PANC...VFR conditions are expected to continue through the
evening, though an MVFR cloud bank sitting near and just to the
west of the terminal could occasionally bring ceilings down to
MVFR range over the next few hours. Conditions Begin to
deteriorate tonight, with snow moving in around 10Z, dropping
visibilities and cloud ceilings to low MVFR. Winds are expected to
shift southeasterly around the time snow begins and increase to
around 15 knots. Snow will rapidly come to an end as the upper
disturbance supporting the expected snowfall moves quickly to the
east by about midday Monday and as southeast winds diminish.
However, there is a chance for low clouds tied to lingering
moisture from the morning snowfall to keep ceilings in MVFR range
into the afternoon.

&&

$$