Gale Warning 214, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
606 PM AKST Tue Mar 4 2025

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

The low that remains south of the Gulf helping to usher warm
southeasterly flow into Southcentral bringing temperatures back up
into the upper 30s and lower 40s will begin to elongate this
evening and exit the region to the southeast through tonight.
Active weather looks to return beginning this evening as attention
shifts to the eastward progression of a much larger system
centered over the Aleutian Islands. A triple point low forming
along a front south of the Alaska Peninsula this evening will be
the immediate focus as the ridge over British Columbia extending
into Alaska recedes to the east. Ahead of the front associated
with this triple point low, sufficient moisture and southeast
winds bring another round of coastal and upslope driven
precipitation for the Kenai Peninsula and Prince William Sound
through Wednesday morning while the cross-barrier flow keeps
inland areas mostly dry.

By Wednesday evening, an additional low will form in the western
Gulf and move north towards the Gulf coast through Wednesday night
into Thursday morning. The uncertainty surrounding the track of
this second low has been advertised the past couple of days as
variance in model guidance remains high run to run. For the time
being, a more easterly track into Prince William Sound looks
favorable with gale force winds along the north Gulf coast and a
better chance for precipitation for the western Kenai Peninsula,
Anchorage, and the Mat-Su Valley. As the low drives north into
Prince William Sound, the weakening of the southeasterly flow and
eventual shift in wind field may allow for precipitation to fill
in over these areas late Wednesday night into early Thursday
morning given sufficient lift and lack of downsloping. Given the
warm airmass in place, precipitation would likely begin as rain
but transition to snow throwout the early morning hours on
Thursday as the supply of warm southerly winds are cut off as a
colder airmass wraps in around the low. Regardless of the
precipitation type outcome, precipitation looks to taper off
through mid morning on Thursday amounting to modest accumulations
should it fall as snow.

&&

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

Currently, an inverted, elongated surface trough has situated
itself along the Southwest coastline, which is producing
precipitation across Bristol Bay and the Kuskokwim Delta regions.
Warm air lurking to the south around Bristol Bay and King Salmon
is keeping p-type to rain. The Kuskokwim Delta is under a much
colder airmass, which is allowing precipitation to remain snow.
This has resulted in an impressive temperature gradient across
Southwest Alaska with single digit temperatures along the
Kuskokwim Coast to upper 30s from Kalskag, east.

Out west across the western most Aleutians, a deep, near storm
force low is located southwest of the chain, which is producing
strong winds and moderate to heavy snowfall near Shemya. At the
same time, waves of low pressure embedded in a surface
trough/front associated with a band of precipitation stretching
from the Central Bering southeastward across the Central Aleutians
and the Dutch Harbor area continues to move eastward. A triple
point low looks to develop near the Pribilof Islands this
afternoon as it encounters a warmer airmass and robust baroclinic
zone. This new low will allow for gusty winds and snowfall of 2-4"
to impact the Pribilofs starting tonight, lasting until Wednesday
afternoon. Due to the likelihood of transportable snowfall and
reduced visibility, a Winter Weather Advisory remains in effect
for the Pribilof Islands.

After the low departs the Pribilof Islands on Wednesday
afternoon, guidance suggests that it begins a northward turn and
skirts up the coast of the mainland. Before the wind inevitably
shifts to southerly from south to north along the coast, a period
of snowfall and gusty northerly winds and possible blowing snow
will impact the Kuskokwim Delta coastline and Nunivak Island on
Wednesday, lingering/tapering off through midday Thursday. 2-4" of
snowfall is likely through this stretch of the coast, which all
said has prompted a Special Weather Statement for these areas.
Warm air advection will quickly follow behind and to the east of
the low as its winds turn southerly, causing mainland Southwest
temperatures to spike from the low to mid 20s to mid to upper 30s
during during the day on Wednesday, causing conditions to improve.
The low will then become nearly stationary in the Nunivak Island
region for the rest of the forecast period, allowing for scattered
light snow showers to persist through Thursday afternoon.

By Thursday night, the operational models depict a transient,
sharp, longwave surface and upper level ridging pattern becoming
situated over the Western Aleutians that will support a brief lull
in any precipitation for these areas, while a pressure gradient,
reinforced moisture fetch off the Bering will bring some light
snowfall for the Central and Eastern Aleutians. The Southwest will
remain mostly quiet from Thursday night through Friday.

-JAR/AM

&&
.LONG TERM FORECAST (Days 4 through 7 - Saturday through
Tuesday)...

Broad upper level troughing will spread across most of mainland
Alaska and down into the Gulf, leading to a generally unsettled
pattern throughout the long term period. Uncertain surface low
tracks and magnitudes will locally enhance weather both in the
Bering Sea and Gulf of Alaska. On Saturday, a surface low ahead of
the upper trough will send a front into the northeastern Gulf
coast. Most heavy precipitation should be pushed toward the
Panhandle, but some weaker precipitation could wrap into
Southcentral as well.

Northerly flow on the backside of the low could cause gusty
conditions through Alaska Peninsula bays and passes as upper
ridging tracks across the Bering Sea and into Southwest Alaska on
Saturday. There is still model disagreement, but it is looking
likely that there will be sufficient northern energy behind the
ridge to suppress it as it reaches mainland Alaska.

The aforementioned ridge will quickly be followed by a stronger
low pressure system coming from the Kamchatka Peninsula. This will
likely bring widespread precipitation and gusty southerly winds
initially to the Western Aleutians before transitioning to more
zonal flow Sunday and Monday for the rest of southern Alaska. As
the system progresses at the end of the weekend and into early
next week, increased precipitation chances for both Southwest and
coastal Southcentral are possible, depending on how lows set up in
the Gulf. Throughout the weekend, a cooling trend with closer to
normal temperatures will reach most of the state.

&&

.AVIATION...

PANC...VFR will persist throughout the TAF period. Light
northerly winds will prevail through tonight. Increasing southeast
winds aloft in response to an approaching system may result in
wind shear from late tonight through much of Wednesday. Gusty
southeast winds out of the Turnagain Arm are likely to bend
towards the airport by Wednesday night, though there remains some
uncertainty on exact timing. Precipitation will also be in the
area throughout much of the day, but will likely remain confined
to the mountains until Wednesday night when the primary trough
axis shifts north.

&&