Gale Warning 114, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
519 AM AKST Tue Jan 30 2024

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

Snowy weather will continue to diminish this morning in wake of a
system that brought several inches of snowfall to southcentral
Alaska, with widespread areas receiving in excess of a foot of snow.
GOES satellite imagery shows the upper-level trough axis gradually
lifting and pivoting northward up through the Kenai Peninsula, with
the eastern PWS and eastern Chugach remaining in southerly flow out
ahead of this trough. Upslope snow and snow shower activity will
remain out ahead of this trough with a few additional inches of
snowfall possible in the Valdez area today, as well as towards
Cordova.

Cold, strong southwest flow that resulted in blizzard-like
conditions across Homer and southern Kenai Peninsula will also taper
off as the day progresses. There remains some uncertainty as to when
the precip will shut off, but winds are expected to shift to a more
northerly direction by the evening, which would affectively shut off
the moisture source for the convection.

Very cold air will settle into place across southcentral Alaska from
midweek and beyond into the weekend. Highs around or below 0 and
lows well below 0 are likely for much of the area outside of
immediate coastal locations along the PWS and Gulf of Alaska. Upper-
level troughing in place coincident with some moisture may keep some
clouds in place. Additionally, any formation of Cook Inlet fog / low
stratus could moderate temps a bit. That said, if conditions can
remain clear one of these nights, it's entirely possible ANC records
its lowest temp since 2009.

&&

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

A deep, negatively-tilted upper trough extending from the Gulf of
Anadyr to Kodiak Island this morning will continue to slowly lift
to the north as the upper-level flow becomes more zonal over the
next couple of days. A shortwave embedded in the flow will deepen
and move from west of Saint Matthew Island this morning to Nunivak
Island for Wednesday morning. At this surface, an attendant
compact polar low is moving in similar fashion. A frontal boundary
attached to this feature is bringing occasional moderate snow and
gusty winds to the Pribilofs this morning. These conditions are
expected to improve a bit later this morning, then return this
afternoon as the surface low passes to the north of Saint Paul.

A second compact low is spinning up just south of Cold Bay this
morning, and is bringing snow and gusty winds to the AKPen. This
feature will quickly drop south and east through the morning
hours, with improving conditions in its wake.

The first low will move onshore near Kuskokwim Bay Wednesday
morning with gusty winds, snow, and blowing snow likely for the
Kuskokwim Delta coast Tuesday night through Wednesday morning.
Snow and localized areas of blowing snow are also likely across
the Bristol Bay coast. This low will quickly weaken through
Wednesday with snow becoming less widespread for interior
Southwest locations as the low tracks inland.

An upper-level ridge then begins to build for Thursday as the
pattern reamplifies ahead of a developing North Pacific low. This
low will move to the central Aleutians by Thursday morning with
its front lifting into the southern Bering. The low is then
expected to track into the western Bering by Friday morning as
its occluded front moves over the Pribilofs and eastern Aleutians.
While temperatures will warm with a southerly flow along the
front, there will likely be enough cold air over the Pribilofs for
a period of snow and blowing snow Thursday. Farther south,
temperatures will likely warm enough for wet snow and mixed
precipitation. The front slows and stalls as it reaches the
Southwest Alaska coast for Friday as a second low and frontal
system advances toward the western Aleutians.

For Southwest Alaska, conditions remain clear and very cold with
morning lows 20 to 30 below zero for most locations. Temperatures
will moderate slightly with the aforementioned surface low moving
over Southwest Alaska. However, temperatures are expected to once
again drop into in the -25 to -35 degree range in the wake of
that system.

&&

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

Looking into the long term, a negatively tilted trough extending
across Southcentral Alaska to the eastern Gulf of Alaska rotates
eastward around an upper-level low centered over the Interior,
reaching Canada and Southeast Alaska by Saturday night. Behind
it, a longwave ridge extends up from the North Pacific into the
Gulf of Alaska ahead of a deep longwave trough that becomes
established in the western Bering Sea for the weekend. A series of
lows rotates through the trough northward into the Bering Sea,
with associated fronts moving into Southwest Alaska as early as
Friday.

Gale force northwesterly gap winds blow across the Gulf of Alaska
Friday morning as robust surface troughing in the eastern Gulf
draws an air mass with around -20C 850 mb temperatures across the
Alaska/Aleutian Range. Expect another round of temperatures 10 to
20 degrees below normal with dry conditions across much of
southern mainland Alaska for the end of the work week. Winds
decrease through the day on Friday as the trough weakens and
shifts east. Out west, the series of lows moving into the Bering
Sea bring in a warmer, more seasonable air mass. The Bering and
Aleutians see a return to active weather and can expect multiple
fronts to bring both rain and snow for the latter half of the week
and through the weekend.

On Friday, a storm force low over the northwestern
Bering Sea pushes a front along the Southwest Coast, likely
bringing only snow, with some rain possible for the Alaska
Peninsula. The front weakens and pushes east for Saturday, but
remains out over the Gulf, avoiding Southcentral and leaving it
dry. A second storm force low pushes northward into the western
Bering on Friday as well, with its front bringing winds as strong
as storm force to the central Aleutians. The front sweeps east
and weakens, reaching the Southwest Coast on Saturday. It pushes
inland, bringing snow to most of Southwest Alaska, while the
Alaska Peninsula and Kodiak Island likely see rain at times. The
front continues to weaken as it pushes into Southcentral for
Sunday, limiting snowfall amounts and coverage, with precipitation
chances decreasing to the north and east. The robust cold air
mass ahead of the front over Southcentral increasingly looks to
keep even precipitation along the north Gulf coast all snow.

By Sunday, another low crosses into the Bering Sea from the North
Pacific, though its track and intensity are more uncertain. It
brings another round of rain and snow to the Aleutians for Sunday,
with the Alaska Peninsula and Southwest Coast seeing precipitation
on Monday. The warmest air yet looks to arrive with this system,
with rain (or freezing rain, both low probability) possibly
reaching as far north as Dillingham.

&&

.AVIATION...

PANC... VFR ceilings and visibility this morning with lingering
MVFR conditions, improving to VFR conditions before noon. Winds
should remain light and southerly to southwesterly today, and
northerly on Wednesday. Expect improving sky conditions through
Friday.

&&