Gale Warning 27, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
435 PM AKST Mon Jan 29 2024

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

Snowy weather will come to an end through the night tonight.
Accumulations across Southcentral have ranged roughly from
5 to 45 inches, with highest snow accumulations near Valdez and
Thompson Pass. Periods of light snow will continue through tonight
across Anchorage and the Mat-Su Valleys, with little additional
accumulation expected. Snow and blowing snow will continue across
the western Kenai Peninsula through this evening before tapering
off. And additional accumulations of 12 to 16 inches is possible
for Valdez and Thompson Pass and the southern Copper River Basin
through tonight. Cordova has transitioned back to snow and will
see up to 6 inches possible of snow accumulation through tonight.

Cold air will return after the precipitation ends, bringing
temperatures back into the single digits and subzero range.

On Wednesday, a low develops near the Kenai Peninsula and tracks
towards the southern Gulf of Alaska, scooting near Kodiak Island.
The eastern half of Kodiak Island is expected to see a round of
snowfall, with 1 to 2 inches of snow accumulation likely.

&&

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

A deep, negatively-tilted upper trough sitting over Southwest is
now very slowly beginning to lift northeast along the
Alaska/Aleutian range. Falling snow ahead of this feature is
confined to the eastern half of the Middle Kuskokwim Valley, while
the remainder of Southwest remains under the influence of a
bitterly cold, Arctic air mass. Northwest winds behind the trough
passage will continue to produce localized wind chill values as
low as -40 to -50. However, winds should diminish later this
evening and end the threat for widespread extreme wind chill
values, despite very cold temperatures lingering in place. Out
across the Bering Sea, mostly zonal flow is in place aloft, but a
sharp thermal gradient remains in place between very cold Arctic
air in place over the sea ice and more moderate temperatures over
open water. A string of several small Polar lows has formed along
this interface, and this complex of lows is still the biggest
source of short range forecast uncertainty.

Across Southwest, the main story will continue to be the frigid
temperatures already in place for the time being. Temperatures
will very gradually increase as weak onshore flow develops and as
the air mass begins to retreat towards the north. This will be
especially the case by Wednesday, as a low evolving from the
complex of small centers over the Bering Sea approaches the
Kuskokwim Delta Coast. There will be some potential for light
snowfall to move inland with this decaying low as it arrives, but
amounts are likely to be very light and on the order of a few
inches or less. A short period of blowing snow is possible along
the coast as light snow begins and southeast winds briefly pick up
ahead of the low's occluded front. Otherwise below average
temperatures and mostly dry conditions will prevail towards
Thursday as the low dissipates.

Out across the Bering Sea, forecast confidence remains hindered by
the complex nature of the low level pattern featuring numerous
small lows drifting near and south of the ice edge. It appears
most of this cluster will consolidate into two main lows; one
moving north of the Pribilofs between tonight and Wednesday, and
the other diving southeast into the eastern Aleutians and southern
AKPen overnight tonight. Uncertainty for the exact track of these
lows is still rather high, but these two systems will bring the
threat for suddenly increasing winds, snow and blowing snow to
the Pribilofs, eastern Aleutians and Southern AKPen as they brush
past from tonight through early Wednesday. From Wednesday onwards,
the pattern begins to amplify as a longwave ridge builds over the
eastern Bering while a deep upper trough sharpens over the western
Bering/Aleutians. A stronger low will move north ahead of this
trough into the central Bering on Thursday, bringing with it
warmer southerly winds up to gale force and increasing chances for
snow changing to rain across mainly the central Aleutians and
Pribilofs through Thursday.

-AS

&&

.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.

CQ

&&

.AVIATION...

PANC...The snow will likely linger through the early evening producing
IFR visibility. The snow is then expected to lighten up with MVFR
conditions through midnight. The ceilings may remain at or just
above MVFR levels into tomorrow as the clouds will be slower to
clear out. Winds will be turn southerly and be a little gusty for
a period of time this evening but are expected to abate after midnight.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
926 PM AKST Mon Jan 29 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0712 PM     Snow             Willow/John Lake        61.73N 150.10W
01/29/2024  M15.0 inch       Matanuska-Susitna  AK   Public

            Measured after snow stopped around 10 AM but
            before wind started blowing.

&&

KC

Preliminary Local Storm Report
National Weather Service Anchorage AK
931 PM AKST Mon Jan 29 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0824 PM     Snow             Anchorage Hillside      61.12N 149.71W
01/29/2024  M13.5 inch       Anchorage          AK   Trained Spotter

            Storm total since 11:00 AM Jan 28 and still
            snowing. Visibility less than 0.5 mi. This
            updates the previous report for Anchorage
            Hillside, issued on Jan 29 at 7:05 AM.

&&

KC

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
221 AM AKST Tue Jan 30 2024

AKZ195-310300-
Pribilof Islands-
Including the city of Saint Paul
221 AM AKST Tue Jan 30 2024

...STRONG WINDS COMBINED WITH PERIODS OF HEAVY SNOW FOR THE
PRIBILOF ISLANDS THROUGH TUESDAY EVENING...

A compact storm system from Siberia is forecast to track across
the Pribilof Islands through the day Tuesday, bringing periods of
heavy snow and strong winds gusting as high as 55 mph. Expect
southeasterly winds early this morning shifting to the west in the
afternoon. Gusty winds combined with heavy snowfall may reduce
visibility to less than one mile at times due to blowing snow. The
worst conditions will be brief, likely lasting only a few hours,
first early this morning and again this afternoon. This system is
expected to bring 2-4 inches of new snowfall to the Pribilofs
during this time. Winds and snow showers will taper off tonight as
the storm moves toward the Southwest Alaska coast.