Gale Warning 374, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
511 AM AKDT Sun May 18 2025

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

The is not much change in the weather over Southcentral as once
again the atmosphere is rather saturated from the surface to 500
mb and there is very weak flow aloft. Looking at just about any
type of satellite imagery early this morning shows a very flat-
looking and rather featureless masses of clouds over
Southcentral. Usually waves can be seen in the satellite imagery
that show where the upper waves are propagating, but today it is
radar that does show a line of showers in Cook Inlet moving
westward and a region of rain entering Prince William Sound from
the Gulf. What is remarkable is just how unremarkable the
satellite imagery is across the entire Southcentral region for
how moist the atmosphere is. This does make it more difficult to
time the development and movement of showers across the region and
much of the area will just see an occasional shower pass through,
except the terrain enhancement along the Gulf coast will bring in
more persistent rain to those areas. This pattern will not change
much for today though there may be some breaks in the clouds with
a little less overall moisture on Monday.

By Tuesday, there should be some movement in the weather as an
upper trough drifting over western Alaska will head northeast into
Cook Inlet and the MatSu. This will help turn low level flow a
bit more onshore, as well as increase rain chances for the western
half of Southcentral after that relative lull in denser cloud
cover and shower activity on Monday. Gap winds through the
typical valleys, including along Turnagain Arm, will once again
pick up Tuesday afternoon as the south-to-north gradient along
the coast resumes.

&&

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

As of this morning, a surface high pressure system is in control
across the Bering Sea, which is permitting breaks in clouds for
the Pribilof Islands, but low stratus could return later in the
day. For the Central Aleutians, a dying surface low situated south
of Adak and Atka is now departing southeastward into the North
Pacific. An upper level wave of low pressure is also dropping
southward across the Kuskokwim Delta and toward the Bristol Bay
region, which may support areas of light rain and somewhat
elevated winds that will last through this evening for coastal
Southwest areas. Other than the upper level wave, a relative lull
in activity for the western domain will persist into early Monday.

Looking forward to Monday afternoon, the upper wave begins to
flatten and slowly lift as weather conditions improve for the
Southwest. Likewise, a stronger Kamchatka low and its attendant
front with sub-gale force winds begins to move across the Western
Aleutians as a 500 mb shortwave moves across the Bering Sea and
over the Pribilofs, giving the islands pre-frontal precipitation.
This upper wave quickly outruns the front to the west, which will
help result in the front falling apart as it moves eastward across
the Central Aleutians early Tuesday. Almost all of the guidance
shows that the front elongates, stalls, and dissipates before it
reaches the Pribilof Islands. A subsequent Kamchatka low and front
reaches the Western Aleutians early Wednesday as the area remains
in a similar pattern.

-AM

&&

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

The weather pattern through the long-term period will remain
relatively progressive in the upper-levels from west to east
Wednesday through Saturday. A low in the southwest Gulf of Alaska
continues to the southeast while it weakens and exits the Gulf to
the North Pacific. Southerly flow off the Gulf keeps clouds around
mainland Southcentral Alaska with most of the rain confined to
the coast and Kodiak Island. Mesoscale easterly shortwaves
crossing the ALCAN border into the Copper River Basin and Susitna
Valley will also keep shower chances going through those areas.
Most showers should be confined to the foothills and terrain.
There is uncertainty in cloud cover and whether any showers could
produce lightning strikes. However, the potential for a few
lightning strikes cannot be ruled out, especially if daytime
heating is maximized.

Farther out west, the pattern remains active with numerous
systems moving eastward off of Kamchatka and into the Bering/North
Pacific. A gale-force low Wednesday looks to weaken as it moves
eastward through Friday. The gustiest winds look to remain across
the Western Aleutians with weaker winds to the east. Most rain
with this system should also remain confined to the Aleutian
Chain, Bering Sea, Pribilof Islands, and southern Alaska Peninsula
with higher pressure across the southwestern mainland. Another
Kamchatka front moves across the Western Aleutians/Bering to the
Central Aleutians/Bering Friday through Saturday bringing another
round of rain southerly winds to the area.

&&

.AVIATION...

PANC...VFR conditions will persist with periods of cloud ceilings
dropping below 5000 ft. Light rain showers are expected through
the day today with a Turnagain Arm shifting over the terminal this
afternoon with gusts to 22kts possible. Winds will diminish
overnight.

&&