Gale Warning 287, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
527 PM AKDT Wed Apr 2 2025

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

A digging trough over the Bering Sea and Aleutians is leading to
amplification of the downstream ridge over southern AK and the
Gulf. While some high cirrus clouds have formed over Southcentral
today, dry conditions and warm temperatures continue across the
region. The amplification of the upper flow will ultimately lead
to a pattern change, with the ridge progressing eastward to Canada
on Thursday, opening the way for a deep trough and Pacific surface
low to impact Kodiak Island, the Gulf waters, and Southcentral AK
Thursday night through Saturday. The forecast for this storm
system is on track, with few changes made to the going forecast.
A strong leading frontal system will track well out ahead of the
parent low, lifting northward across the Gulf Thursday night and
then stalling over the northern Gulf Friday afternoon through
Saturday afternoon as a vertically stacked low sets up shop south
of the Alaska Peninsula and Kodiak Island. The vast majority of
impacts from this storm will be along the coastal zone, with
strong easterly winds and rain. Snow levels will remain fairly
high, starting out at around 1000 to 1500 feet early Friday
morning, then rising 1800 to 2500 feet by late Friday. Thus, snow
should not be a big issue along the road system. Inland areas will
remain mostly dry with strong downsloping flow, though there
could be an occasional brief period of light precipitation as weak
upper short-waves track inland. Temperatures will remain above
normal, with a trend toward above freezing night-time temperatures
due to extensive cloud cover.

-SEB

&&

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

Key points...

 * Winter Storm Watch upgraded to Warning for Unalaska
    -Heavy wet snow, blowing snow and reduced visibilities
    -Onset early Thursday morning

 * Blizzard Watch for the Kuskokwim Delta Coast continues
    -Strong winds with blowing snow
    -Onset Thursday morning

Very little to the weather picture has changed over the last 12
hours, other than fine tuning of warning products. A deepening
north Pacific low continues to lift towards the Aleutian Chain
this afternoon. A warm front lifting ahead of this low will slam
into a cold front that lay draped from Norton Sound, southwest
through Adak. The low is expected to slow down and stall through
Friday, southwest of Kodiak Island. Where the interaction of warm
moist air from the south and cold arctic air from north collide,
heavy snow will occur. Current guidance is putting the island of
Unalaska right in the cross-hairs. Unlike the early winter storm
that brought similar snow amounts to the island, the bulk of the
dynamics will remain south of the chain. That said, conditions are
still going to be favorable to produce a lot of heavy and wet
snow over a prolonged time period. Snow totals for the city may be
lower side of expectations, but the influence of terrain will
allow those totals to swell rapidly with minimal elevation gains.
Unalaska and the harbor are should see 10 inches to more than a
foot, while amounts over a foot and a half cannot be ruled out.
The other aspect of this event will be the winds. Winds and cold
air will be driving across the Bering and will easily be
sustained above 25 mph, starting around dawn on Thursday with
gusts at or above 40 mph. Winds will steadily increase and peak in
the overnight hours on Thursday, lasting into Friday, potentially
surpassing 60 mph gusts. The combination of the driving winds and
periods of heavy snow will lead to whiteout conditions. Snow will
taper off Friday into Saturday with winds abating later into
Saturday and Sunday.

North along the Kusko coast the blizzard watch continues. Trends
are starting to focus more on the bulk of the snow pushing later
into the day and along the far western coast (Kipnuk to Toksook
Bay and across to the Nunivak Island). Blizzard conditions are
looking a little less likely, but blowing snow will still be a
hazard.

&&

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

The most significant feature on the Alaska Weather map is an
elongated trough stretching from the Arctic through Interior
Alaska to the Gulf of Alaska through the forecast period. Closed
lows over Northern Alaska and the Gulf weaken through midweek.
Although there is some oscillation within the elongated trough,
there is little movement. Ridges over the Western Canadian
Provinces and the Bering also weaken through the period. Forecast
continuity remains good with a GFS / ECMWF / Canadian blend, but
minor differences with shortwaves gliding through the pattern
represent the variations and short term changes in forecast.

A moderately strong surface low over the Southern Gulf of Alaska
spreads locally heavy rainfall from the Eastern Aleutians over the
Alaska Peninsula through Monday. Gusty winds over the AKPEN
linger through midweek. Locally heavy rains marches across Kodiak
Island and the rest of Southcentral Coastal zones through
Wednesday. Areas of locally moderate snow spread over Southwest
Alaska into the Interior, and diminish through midweek. A well
developed low and front approaches the Western Aleutians for
Sunday, but dissipates to the South of the chain by Tuesday.

- Kutz

&&

.AVIATION...

PANC...VFR conditions are expected to continue through the TAF
period. A ridge of high pressure is developing along the coast,
which will induce winds through Turnagain Arm this
afternoon/evening. Given the warm temperatures and heating in the
Valley, there's a chance the wind moves over the terminal this
afternoon/evening. We're not anticipating a strong wind at this
time but gusts up to 20 kt are possible. Calm conditions are then
expected overnight, with a return of the Turnagain wind possible
Thursday afternoon and evening.

&&