Gale Warning 368, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
417 PM AKDT Mon May 12 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Tonight through Wednesday Night)...

After a beautiful weekend, unsettled weather has returned for
Southcentral Alaska as a front arching back to a low in the Central
Bering has brought widespread precipitation to the majority of the
area. As of mid-afternoon Monday, many lower elevation areas from
the western Kenai Peninsula north through Anchorage and the Susitna
Valley have received 0.25" to 0.50" of rainfall, with a few
isolated higher amounts. Rain has also fallen from the Mat Valley
east through the Copper River Basin, where amounts generally
around a tenth or less being reported thus far.

As we head into the evening, precipitation will gradually taper off
across the western portions of the area, though linger across the
Greater Copper River Basin thanks to a trough dropping south through
Yukon and far Eastern Alaska. While much of the area remains too
warm for snow, light snow accumulation towards Isabel Pass and
nearby Summit Lake will be possible.

Tuesday will bring a quick return to pleasant weather for much of
Southcentral Alaska as ridging amplifies ahead of an upcoming
system. The resultant clearing skies will allow temperatures to warm
back into the mid/upper 50s for much of the area. The Copper River
Basin will hold onto cloud cover a bit longer too, but should
receiving clearing skies later in the day.

A deepening low pressure system will move up from the North Pacific
towards the AK Peninsula on Wednesday. The associated front will
push through Kodiak Island Tuesday night, bringing gusty winds and
heavy rain to the island. Gale-force winds are expected across much
of the Gulf with the frontal passage, as well as through the
Barren Islands and Shelikof Strait. The front reaches the Kenai
Peninsula by Wednesday morning, with rain across the eastern/Gulf-
side of the Peninsula, as well as Prince William Sound. The lee
side of the mountains will remain largely downsloped and dry as a
result, though gusty winds can be expected through many of the
gaps, including Turnagain Arm.

-Brown

&&

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

The strong storm system which affected the region is now nearly
stationary over the central Bering Sea. The low is vertically
stacked and slowly weakening with time, leading to diminishing
winds. The cold front which swept across Southwest AK today
weakened significantly as it exited toward the western Interior.
A showery regime with locally gusty winds can be found behind
the front, with the bulk of precipitation over the Bering Sea.

The upper level low in the Bering Sea has taken the place of the
previous low from a couple days ago and will now anchor the long-
wave trough. The subtropical jet stream over the North Pacific
remains quite robust (~145kt or so). This will support continued
cyclogenesis near the left exit region of the jet, with lows
being steered northward toward the eastern Bering Sea and southern
AK. Prior to that, however, a weak low will form south of the
western Aleutian chain tonight as a short-wave rounding the Bering
low digs into the North Pacific. The upper jet to the south will
quickly continue eastward and lead to cyclogenesis downstream.
As a result, the first low will remain quite weak as it lifts
north to the central Aleutians Tuesday. The main impact will be
an uptick in southerly gap winds for the Eastern Aleutians and
southern Alaska Peninsula, along with another round of rain.

The second low which forms in the Pacific will be in a favorable
location to deepen and will take a further east track to near
Chignik (along the south side of the Alaska Peninsula) on
Wednesday. A leading gale force front will lift northward across
the Alaska Peninsula and into Bristol Bay Tuesday night through
Wednesday. This will bring strong and gusty easterly winds on the
order of 40 to 55 mph to much of the Bristol Bay region. The bulk
of rain with this system will be confined to upslope areas,
including the south side of the Alaska Peninsula and areas north
and west of Dillingham.

&&

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

There is loose agreement with ensemble guidance that an upper
level trough will move from the Bering Sea to the Gulf of Alaska
Friday through Monday. Operational guidance shows variations of
this setup but has poor agreement with regards to timing of
surface features.

Ridging looks to develop behind the Bering trough Friday and move
eastward from the Western Aleutians to the Central Aleutians as
it weakens. Expect quieter weather across these areas while
underneath the ridge. Meanwhile, troughing will linger across the
north Gulf Coast through Sunday with rain continuing along the
coast of Southcentral with diurnal showers developing across
portions of Southwest through Monday. A North Pacific front looks
to lift northward through the Gulf Sunday and Monday with spread
on the track of the low center itself ranging from remaining south
in the North Pacific to a more northerly track into the central
Gulf to near Kodiak Island. Regardless of the low track, the
Alaska Peninsula to Kodiak Island look to be the wettest with more
uncertainty in the precipitation forecast for the Eastern Kenai
Peninsula and north Gulf Coast due to just how far north the front
will end up lifting.

&&

.AVIATION...

PANC...MVFR to VFR conditions will become all VFR by late this
evening as drier air works in behind a cold front pushing through
Southcentral Alaska. More steady rain will become more showery
this afternoon then gradually winding down tonight. Turnagain Arm
winds will continue to bend into the terminal over the next few
hours then quickly die off behind the front.

&&