Gale Warning 812, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
320 AM AKST Mon Nov 11 2024

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

GOES Nighttime Microphysics RGB imagery reveals a mostly clear sky
across Kodiak Island and a large portion of Southcentral AK. Some
high level cloud cover persists across the Gulf of Alaska and
portions of the Copper River Basin, connecting southward along a
trough axis to the area of low pressure in the southern Gulf of
Alaska that's drifting southward. The clear or mostly clear skies
have resulted in excellent radiational cooling overnight, with
temperatures dropping to below 0F in the colder pockets of the
Copper River Basin, with much more widespread single digits and
teens in the Mat-Su Valley, as well as the colder areas of the
Kenai Peninsula and Anchorage bowl.

As we progress into the daylight hours today, generally quiet
weather is set to prevail with largely sunny skies outside of some
passing cirrus. The main weather focus today will be that of the
offshore gap winds flowing out of all the usual places. The
strongest of these winds will be out of Kamishak Gap / Bay, where
gale-force (>34kts) winds were shown on an ASCAT pass last evening
and is expected to persist into this morning before a brief
abatement later today until cold air advection ramps up on the
backside of an area of low pressure moving through the southern Gulf
of Alaska. Gale-Force winds will then persist through much of
Tuesday, with small-craft (>23 kts) winds out of the Copper River
Delta, Resurrection Bay, and potentially out of Passage Canal and
Valdez. For land areas, Thompson Pass will be the winner with
offshore speeds picking up through Wednesday where winds may
exceed 30 or even 40mph at times.

A weak upper-level trough crossing Tuesday into Wednesday will help
a weak area of low pressure in the northeast Gulf organize a bit.
With most weak systems, model spread remains large and thus, so do
the details. But current thinking is precipitation will ramp up in
the northern/eastern Gulf those days, with precipitation primarily
affecting areas from the eastern Prince William Sound east towards
Cordova. Should enough moisture be drawn up from the Gulf towards
the Copper River Basin coincident with the trough passage, some
light snow may possible for much of the basin. Given aforementioned
winds expected across Thompson Pass, we'll continue to pay close
attention to how the pattern evolves and monitor for any impactful
weather.

For Anchorage, Kenai Peninsula, Mat-Su Valley, and Kodiak Island...
mostly quiet weather will continue through mid-week with days
becoming progressively colder. Also there should be a fair amount of
sunshine each of the days outside of some upper-level cirrus. Enjoy!

-Brown

&&

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

Ridging extends into Southwest Alaska today. Areas of patchy fog
is possible across portions of the Kuskokwim Delta and low
stratus will persist across the lower Kuskokwim Valley.
Otherwise, conditions across most of Southwest will be relatively
benign today and Tuesday. A couple of troughs move into the
western Bering Sea today and will meander eastward through Tuesday
night. The trough(s) reach the Southwest Coast by Tuesday night.
Precipitation spreads across the coast as a rain/snow mix before
spilling inland. Inland areas are expected to see lighter
precipitation and will remain as all snow.

The next weather driver for Southwest and the Aleutians is a North
Pacific low looking to cross over the Central Aleutians Wednesday
and make towards Southwest through Thursday. Though there is
still quite a bit of model disagreement, keeping uncertainty
levels high, it is expected that Southwest Alaska will see
widespread snowfall, except along the coast who may transition to
a rain/snow mix.

&&

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

An emerging North Pacific low will make its way into the central
Bering early Thursday before moving towards the southwestern
Alaska coastline by Friday morning. Recent trends in
deterministic and ensemble model guidance has suggested a slightly
deeper surface low by the time the low reaches southwest Alaska,
dropping below 980 mb. In addition, guidance has focused on a
solution where the low center will make its landfall over Nunivak
Island and the Kuskokwim River Delta. The potential for widespread
precipitation and some gale-force winds still exists with this low
as it progresses over Southwest.

As additional shortwave energy moves ahead of the low, a triple
point low is expected to form along its front on Friday near
Kodiak Island. The triple point low is currently expected to
become the dominant feature by Saturday as it moves towards Prince
William Sound. Widespread precipitation, mainly in the form of
snow, will take place over most of Southcentral, with heavier
precipitation occurring along the coastal mountain ranges. Behind
the low, cold Arctic air will be carried southward due to the
support of the upper level trough that will situate itself over
mainland Alaska by Saturday. Though the coldest stretch of
temperatures won't occur until after the end of the extended
forecast period, Sunday lows for many inland locations could get
into the single digits, with potential subzero lows in the
days following.

&&.AVIATION...

PANC...VFR conditions and light winds will persist.

&&