Small Craft Advisory 340, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
540 AM AKDT Tue Apr 15 2025

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

The forecast remains on track for a high pressure ridge today and
generally quiet weather for Southcentral. The exception will be
for Kodiak Island this afternoon as a front lifts into the Gulf.
Later tonight, that front continues to lift farther north,
increasing precipitation chances for the Kenai Peninsula and
western Prince William Sound. Some cooler air could dam up against
the Kenai mountains leading to the initial onset of precipitation
as snow before warmer air scours out the cooler air Wednesday.
There is ample moisture associated with this system and rain could
become heavy at times. Seward could see 1.5 to 2.5 inches of rain
through Thursday morning. The majority of which is expected to
fall in the 24 hour period from Wednesday morning through Thursday
morning. Amounts will depend on the flow through and across the
area as the front progresses in time.

Gusty winds could also become potentially damaging Wednesday.
Winds of 75 mph or greater is looking more likely for the Portage
Valley, through Turnagain Arm, and affecting higher elevations
such as the Anchorage Hillside and Eagle River. Communities that
are easily subjected to southerly and easterly terrain gaps will
also see gusty winds Wednesday. The Matanuska Valley and Copper
River will likely have gusts of 35 to 45 mph with an isolated gust
to 60 mph possible for the Butte and Palmer area. Anchorage Bowl
will also experience gusty winds, though there is less confidence
on the strength of the winds due to the influence of down Inlet
flow that would help to bend the Turnagain Arm jet southward.

General improvement is expected for Thursday as the low pushes
east through through the Gulf. Models slightly differ in the
surface features and embedded troughs, but lingering showers will
be possible along with southerly gusty winds into Friday.

&&

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

Key Points...

* A Winter Storm Warning is in effect for the Eastern Aleutians
  now through 1 AM Thursday. Expect snow and blowing snow with 8
  to 20 inches of accumulation and gusts of 50 to 65 mph.

* A Winter Weather Advisory is in effect for the southern AK
  Peninsula until 11 AM this morning (Tuesday). Expect snow and
  blowing snow with 2 to 6 inches of accumulation and wind gusts
  up to 45 mph.

* A Winter Storm Watch is in effect from this evening (Tuesday)
  through Wednesday evening for the Kuskokwim Delta Coast. 2 to 6
  inches of snow is possible along with winds gusting as high as
  45 mph and visibility as low as one quarter mile.

* A Special Weather Statement issued for the Western Capes
  concerning a period of snow, blowing snow, and reduced
  visibility from this afternoon through this evening before a
  changeover to rain commences.

The forecast remains mostly on track. The well-advertised powerful
North Pacific low will continue to track to the northeast today,
over the southern Alaska Peninsula (AKPEN) late tonight, and into
the eastern Bering Wednesday morning. Snow will continue to pick
up in intensity today across Unalaska. The heaviest snow is
expected to fall early this evening through early Wednesday
afternoon before snow rates begin to decrease. Akutan looks to
also see a prolonged period of snow due to the slight jog east in
storm track which will allow cold air to hang on longer.
Elsewhere, Cold Bay, False Pass, and King Cove are all reporting
snow this morning with the worst conditions from King Cove
westward. Warmer air is expected to advance northward and turn
precipitation over to rain/snow mix and eventually to rain by this
afternoon across the southern AKPEN.

The front will continue to advance northward to the mainland
Southwest coast by early afternoon. With cold air initially in
place across the Bristol Bay and the northern AKPEN, a period of
snow is expected late this morning into the afternoon before a
change over to rain occurs this afternoon and evening. Southeast
Kamishak Gap winds will be particularly gusty into Iliamna, New
Stuyahok, and Koliganek this evening into Wednesday before
diminishing Wednesday evening. These winds will provide the warm
air and limit the snow period for the interior. The Western Capes
look to remain colder for longer as opposed to interior Bristol
Bay. As snow arrives there this afternoon in conjunction with
increasing easterly to east-northeast winds, visibility could be
significantly reduced around Goodnews Bay and Platinum. The worst
conditions will be around Cape Newenham before warmer air works in
through tonight and changes precipitation to rain.

The front then makes it into the Kuskokwim Delta and Kuskokwim
Delta coast late Tuesday night into Wednesday morning. The coldest
locations will be Mekoryuk, Toksook Bay, and Mertarvik where they
have the best chance at seeing blizzard conditions Wednesday
morning into Wednesday evening; especially for Mekoryuk where they
look to stay the coldest for the longest time.

Meanwhile, showery conditions continue across Bristol Bay and the
the AKPEN for most of Wednesday and Thursday. Steadier
precipitation will occur in the Lower Kuskokwim Valley as the
front continues to push inland during the day. Cold air wraps
around the storm from the north and through the eastern Bering to
the southern AKPEN on Wednesday as the low center continues to
linger weaken and linger around Cape Newenham. With upper-level
shortwaves continuing to pivot and drop southward around the
storm, the southern AKPEN could see another round of snow showers
with reduced visibility at times Wednesday evening into Thursday
morning.

Finally, this low opens into a trough Thursday afternoon and
evening with showers beginning to diminish across mainland
Southwest Alaska Friday morning. Showery activity will be more
confined to the higher terrain the Kuskokwim Mountains,
Alaska/Aleutian Ranges as westerly upslope flow ensues.

Farther out west, a Kamchatka low will send its front into the
western Bering and Western Aleutians late Wednesday night. This
will be a warm system and one that is not overly strong. Expect
some gusty southeasterly winds and rain to move from the Western
Aleutians Wednesday night to the Eastern Aleutians by Friday
morning. Another weak North Pacific low approaches the Western
Aleutians Friday morning with another round of rain and southeast
winds.

&&
.LONG TERM FORECAST (Days 4 through 7/Fri through Mon)...

Low pressure will push into the central Aleutians by midweek,
then move up into the AKPEN for Thursday and into the northern
Gulf by the end of the week. This low will bring a widespread mix
of rain and snow to southcentral for Friday and Saturday, becoming
more showery as the low moves east into the panhandle by Sunday.
Behind this system, high pressure will build north into the Gulf
on Sunday to help dry things out.

In the west, a Bering low will stall out in the central Bering
and begins to weaken as it remains nearly stationary through
Monday. This system will bring periods of rain and windy
conditions to the the Aleutians and coastal western Alaska, but
there remains some uncertainty as to whether this system will
remain strong or stay in place.

- Baker

&&

.AVIATION...

PANC...VFR conditions are expected. Winds from Turnagain Arm will
strengthen this afternoon and then weaken tonight. Low level
windshear is possible Wednesday morning if surface winds remain
light at the airport and stronger winds above the surface and
through Turnagain Arm arrive Wednesday morning. Gusts to 30 mph
returns to the terminal by Wednesday afternoon, but confidence is
low whether stronger winds will bend toward the terminal from
Turnagain Arm.

&&