Small Craft Advisory 552, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
454 PM AKDT Sat Jun 21 2025

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

Discussion:

Hot, dry, windy conditions continue this afternoon in the Copper
River Basin, where a red flag warning remains in effect until 10
PM AKST this evening. A pattern change is on the horizon as an
upper level ridge continues to move east into Canada, allowing a
large low in the southern Bering to increase southerly flow into
Southcentral. This will bring several shortwave troughs up
through the Gulf. Model agreement remains poor to moderate
concerning the timing and strength of these waves, however,
southerly flow will increase cloud cover, lower temperatures
slightly, raise the relative humidity, and improve air quality by
evacuating residual haze of the past several days.

The NAM and ECMWF are most in agreement that Light rain will
start this afternoon across the eastern Kenai Peninsula and
continue through Sunday. By early Monday morning, southeasterly
flow brings rain into Cordova, Valdez, and potentially the Copper
River Basin with lower chances (due to downsloping) for the
Anchorage bowl and MatSu regions by the afternoon. A second wave
also sweeps across Kodiak late Monday, which intensifies and moves
north into Cook Inlet by Tuesday morning.

&&

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

An upper level low spinning just north of the Central Aleutians
is becoming vertically stacked with a nearby 996 mb surface low.
Although the surface low has reached maturity and has begun to
occlude, foggy and misty conditions will continue through the
weekend for the Pribilof Islands.

Onshore flow for coastal and parts of the mainland Southwest is
causing areas of light rain for the Kuskokwim Delta. Fire danger
levels are trending down for the short term due to light rain and
cloud cover, although chances for wetting rain (0.1 inches in a 12
hour period) remain low. Temperatures will remain on the cooler
side across Southwest due to the southerly flow off of the Bering
Sea. Southeast winds through Kamishak Gap into Interior Bristol
Bay and the Kuskokwim Valley will begin to diminish early this
evening into the overnight hours. A warming trend will begin into
the new work week as low-level to mid-level flow becomes more
southeasterly Monday and into Tuesday. Clouds and showers will
linger with upper level shortwaves lifting across the area from
the North Pacific and Bering Sea.

Farther west, gusty southeast winds continue across the southern
Alaska Peninsula (AKPEN), especially through Cold Bay, through
Sunday evening before winds slowly begin to relax. Gusts should
peak up to 45 mph this afternoon and evening. Showery conditions
will also persist through the weekend and into the new work week
across the southern AKPEN with low cloud ceilings and off and on
showers across the Eastern Aleutians. Another front works eastward
from Kamchatka Sunday morning to over the western Bering and
Western Aleutians by Sunday evening. Southerly gale-force winds
are expected to accompany this front across the Western Aleutians
before it quickly begins to fall apart and its winds weaken to
small craft as it reaches the Central Aleutians Monday and the
Eastern Aleutians, Pribilof Islands, and southern AKPEN Tuesday.
The heaviest rain is expected to be confined across the western
Bering and Western Aleutians Sunday evening with light to moderate
rain across the Central Aleutians Monday and light rain across
the Eastern Aleutians, Pribilofs Islands, and southern AKPEN for
Tuesday. What is left of the front will merge with the remnants of
the aforementioned occluded low/trough heading into Tuesday.

-DN/AM

&&

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

We are beginning to get a little more motion in the weather
systems across the Alaska region through the forecast period. A
closed upper level low over the Central Bering begins its trek
across the Alaska Peninsula into the Gulf of Alaska by the
weekend. Several shortwaves rotating through the pattern help
accelerate its movement, and help set up some Easterly wave
conditions across Southcentral Alaska. The upper level ridge
across the Northern portions of Mainland Alaska drift into the
Arctic through Saturday. Forecast guidance begins with a
deterministic blend of GFS / ECMWF and Canadian models that
diverge early in the period, so a change to ensemble means will
carry the large scale features through the rest of the forecasts.

Diminishing warmer temperatures over Interior Alaska helps draw
down the possibilities of convective activity across the Central
Alaska, with the last of the showers and thunderstorms occurring
in the Eastern border zones. A slowly weakening surface low near
the Pribilofs slips across the AKPEN into the Central Gulf of
Alaska by the weekend. Windy conditions close to gale force slips
over the Western and Central Aleutians for Wednesday. Gusty winds
cross the Central Aleutians late Thursday into early Friday.
Widespread rain over the Eastern Bering moves over Southwest
Alaska, AKPEN and Kodiak Island through Friday and spread along
the Southcentral coast through Saturday. Gusty Easterly winds set
up over the Northern Gulf of Alaska late Friday into Saturday. A
moderately strong North Pacific low approaches the Western
Aleutians with rain for Friday before heading back into the North
Pacific for Saturday.

- Kutz

&&

.AVIATION...

PANC...VFR conditions will persist. Southeast winds developing
along the Turnagain Arm may bend into the terminal this evening,
with occasional gusts up to 25 kts. However, there is still a
chance these Turnagain Arm winds don;t bend toward the north
enough to move over the terminal which would keep westerly winds
prevalent as they are the result of the eddy shearing off the
core of stronger Turnagain winds. Either way, the winds will
slowly diminish and become more southerly overnight into early
Sunday morning.

&&