Gale Warning 217, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
510 PM AKST Wed Mar 5 2025

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

A front moving north across the Kenai Peninsula and northern Gulf
this afternoon is bringing gusty easterly to southeasterly winds
and precipitation along the coast. Strong southeasterly flow aloft
continues to keep most of inland Southcentral downsloped and dry
for now, aside from weak radar returns and light precipitation
being observed over portions of the western Kenai Peninsula this
afternoon. Coastal precipitation along the eastern Kenai
Peninsula will taper off from south to north with the frontal
passage. By this evening, a weak triple point low is expected to
develop along the front in the northern Gulf and move north into
Southcentral overnight through Thursday morning bringing the
greatest chance for unsettled weather to Anchorage and the Mat-Su
Valley areas along with coastal rain and snow at higher
elevations. Models coming into better agreement suggest the low
taking a track further to the east moving north into Prince
William Sound. The biggest uncertainty in the forecast continues
to be the precipitation type for inland locations and if enough
cold air will advect into the Cook Inlet region and Mat- Su
Valley with the upper level trough to change rain over to snow
before the bulk of the precipitation ends.

As the parent low associated with the front moves north along the
western coast of Alaska towards Nunivak Island, the pressure
gradient becomes more favorable for southerly winds up Cook Inlet
and winds out of Turnagain Arm moving over Anchorage this evening
likely keeping temperatures above freezing through late tonight
for Anchorage and the Matanuska Valley. The timing of the front
pushes most of the precipitation through during the evening to
shortly after midnight, likely resulting in a scenario where these
areas see rain throughout the evening with a possible transition
to a rain/snow mix and eventually snow as the precipitation begins
to wind down through the early morning hours on Thursday. The
greatest snow amounts are expected for the Anchorage Hillside as
well as Palmer due to favorable south to southwesterly flow, with
additional snow showers allowing these areas to pick up an
additional couple of inches of snow throughout Thursday morning.

&&

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

Currently, an active weather pattern continues for the Southwest
and the Aleutians. Going from east to west, an area of low
pressure located north of Bristol Bay and the AK PEN is associated
with a stationary boundary/surface trough draped just inland of
the mainland coastline. This low is producing gusty winds and
strong warm air advection for areas north of Bristol Bay and King
Salmon into some of the interior Southwest, which is causing some
p-type issues due to temperatures currently in the mid to upper
30s in this area, whereas cold air already wrapping in on the
backside of the low has changed rain to snow for Bristol Bay. To
the north over the Kuskokwim Delta and Nunivak Island,
temperatures are somewhat colder in the mid to upper 20s, which is
supporting snowfall with the front acting as a focusing
mechanism. Heading farther west into the Bering, we are still
watching for the potential of some lingering sub-advisory level
blowing snow and reduced visibility issues over the Pribilofs due
to a lingering secondary area of low pressure entangled in a large
low pressure complex circulating from the western Aleutians to
the Southwest. Finally, a third area of low pressure now located
southwest of Adak is bringing intermittent rain and snow showers
and reduced ceilings to the Western Aleutians, as it seems far
enough away to just bring minimal impacts to these locales.

As this afternoon and evening wears on, the first low affecting
the Southwest will continue to quickly skirt northward up the
mainland coastline. As cold air continues to wrap in on the
backside of the low, locations just northwest of Dillingham will
see snow adding up to 2-4". Although winds look to remain
elevated, guidance suggests that temperatures do not cool off
enough to warrant a threat for blowing snow, but will monitor for
any notable changes in model guidance. 1-2" of snowfall this
evening appears likely for the Kuskokwim Delta as the low moves up
the Southwest coastline. By early Thursday, the low stalls out
and begins to meander near Nunivak Island. Surface temperatures
plummet as much colder air wraps in to the northwest of the low.
As a result of significantly colder air in the single digits over
the Island, which will coincide with a prolonged period of gusty
northwesterly winds, as well as guidance that there is
transportable snow on top of any ice in this region, this all
brings into question if whether or not advisory level blowing snow
will be an issue. The main uncertainty revolves around the exact
positioning of the low; if the center wobbles any farther west,
this threat diminishes as northwesterly winds will also be pushed
farther west. Current guidance does point at this scenario
materializing, so the most northwestern part of the island has the
best chance of seeing any significant impacts at this time. We
currently do not have any advisory products out, but will monitor
closely as more model data comes in. For the Pribilofs around this
time frame, both the GFS and the NAM have their area of low
pressure dissipating and being absorbed into the aforementioned
stronger and larger low affecting the Southwest coastline to the
east with any blowing snow and visibility reductions coming to an
end. For the Western and Central Aleutian chain, the low affecting
these areas digs farther south and east, leaving behind nuisance
snow showers as the larger low complex pivots and resembles a
longwave positively oriented surface trough with two remaining
areas of low pressure systems (one over Nunivak and one south of
the Aleutian chain).

By Friday morning, the low affecting Nunivak Island is still
meandering in place and steadily weakening with little upper
level support, which should bring any blowing snow to an end for
this timeframe. For the Central Aleutians, operational models
still show the pressure gradient between a ridge building across
the Western Aleutians, and lower pressure for points eastward,
forcing a fetch of moisture originating from the central Bering
across the region. This should be a low impact snow and wind
event, as guidance has backed off on the force of the gradient in
the most recent runs, mostly due to the Southwest low dissipating
faster and the ridging now not coming in as sharp and pronounced
in comparison to previous model runs. The ridge will be transient,
though, as another Bering gale-force low/front with widespread
gales is fast on its heels by late Friday with another round of
precipitation for the Western Aleutians.

-AM

&&

.LONG TERM FORECAST (Days 4 through 7 - Sunday through Wednesday)...

An elongated upper level trough extends from Siberia and the
Russian Far East across the Bering into Bristol Bay Sunday. This
trough continues to extend across the Gulf of Alaska with a low
center Monday that exits to the Southeast by Wednesday. A number
of shortwaves slide through the pattern across the Aleutians
before dropping into the Eastern North Pacific through the
forecast period. By Wednesday, a weak trough extends across the
Southern two-thirds of the state. A weak upper level ridge over
Interior Alaska for the weekend reorients along the Arctic Coast
by midweek. A semi-organized cluster of GFS / ECMWF and Canadian
models maintain the larger scale features. The shortwaves through
the pattern enhance the uncertainty with the surface details
through the week.

The forecast opens with a well developed low in the Western
Bering that weakens and moves to the Eastern Bering for Tuesday.
An extensive area of gale force winds are expected across the
Western and Central Aleutians diminishing through Tuesday, with
mid-range storm force gusts over the Western Aleutians through
Monday. A front extends across from the low over the Bering with
widespread snow wrapping around the low and spanning open waters
with the front over the Bering. The Bering portions of the front
stretches into the Bering Strait and Western Alaska, diminishing
for Wednesday. Weather changes to rain over and South of the
AKPEN. A surface low forms on the front near Kodiak Island late
Sunday and the system pushes the rain across the Gulf coasts
through Tuesday. Another front brings areas of rain and snow over
the Western and Central Aleutians late Monday through Wednesday

- Kutz

&&

.AVIATION...

PANC...VFR will prevail throughout much of the TAF period with the
possible exception of late this evening with a chance of rain and
snow. Light northerly winds early this afternoon are expected to
becoming gusty and southeast of the Turnagain Arm. Shortly
thereafter, a band of rain transitioning to snow is expected to
cross the terminal this evening. Uncertainty remains regarding
duration and total snow amount, but amounts generally look to be on
the lower side and may be limited by temperatures struggling to go
much below freezing. After perhaps a brief period of MVFR CIGs/VIS
to go with this, precipitation and gradual improvement in conditions
otherwise are expected in the overnight hours with continued
improvement on Thursday.

&&