328
FXAK68 PAFC 181247
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
447 AM AKDT Sat Jul 18 2026

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

A deep and amplified upper low will bring an atmospheric river
(AR) to portions of Southcentral over the weekend and into next
week. Ahead of the AR today will be some light showers and
increasing gap winds as a coastal ridge builds. The winds will be
similar (though slightly weaker) to the wind event earlier this
week. Tonight the main plume of moisture will arrive with deep
south-southeast flow aloft. With this flow direction, and a few
embedded shortwaves, the eastern Kenai Peninsula and western
Susitna Valley will be favored for moderate to heavy rainfall.
Seward will likely receive the most, with 4 to 6 inches of rain
expected through late Monday. Anchorage will have some
downsloping, but perturbations moving through the southerly flow
may bring periods of light rain, especially in this moist
environment. If anyone is looking for nicer weather, the Copper
Valley is the place to go with some ridging helping keep the area
warm and dry.

By Tuesday the upper trough will take on a negative tilt and begin
to move east, spreading moisture to the rest of Southcentral on
Tuesday. Looking ahead, more of the same. Rain.

&&

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

The wet and active pattern is here to stay, at least through the
short-term period, across Southwest Alaska. A low currently just
north of Unalaska early this morning will begin turning northward
today after heading south for most of its life-cycle. As it turns
north, it will slowly weaken as it heads to around Kuskokwim Bay
through Sunday. This low even lingers into Monday before it
becomes an open trough along Kuskokwim and Bristol Bays. Expect
rain across the majority of Southwest today through Monday with
lighter and more showery precipitation for Monday.

The main 500mb trough persists across much of the eastern Bering
through the short-term. A shortwave will move off of the Eastern
Russian Coast Sunday and cause another surface low to develop in
the northwestern Bering Sunday afternoon. Guidance early this
morning has trended towards a more northerly track through the
Bering and keeps the low around Saint Matthew Island by early
Tuesday morning instead of moving the low southeast towards to the
Pribilof Islands. The front will still bring the Pribilofs rain
for Monday. The front will then bring widespread rain to Southwest
Alaska for late Monday into Tuesday as the low center heads
towards Saint Lawrence Island. This more northern track will also
bring in a fetch of southerly to southeasterly winds into
Kuskokwim Bay Monday night into Tuesday. Tides, at this time,
look relatively low and the fetch of winds into the coastline is
mostly at small-craft strength with some embedded gales. We will
continue to monitor the evolution of this system.

Farther out west, Nikolski/Unalaska/Akutan will continue to
contend with northerly flow off of the Bering for most of today
and will see off and on showers before they taper off Sunday as a
shortwave ridge builds in. Showers will persist across the AKPEN
through much of Sunday as they will still be under the influence
of the weakening eastern Bering low. Weak shortwaves dive
southward from Kamchatka along the precipice of an amplified
upper-level ridge in the North Pacific well west of Shemya. As a
result, these weak waves will bring light rain to the Western
Aleutians, including Shemya, today through Sunday. Light rain also
reaches Adak/Atka by Sunday with the weak waves tracking farther
eastward. Rain will occur along the Eastern Aleutians
(Nikolski/Unalaska/Akutan) on Monday as the newly developed Bering
low tracks southward. Again, depending on the progression of this
low, rain will either begin in the morning or afternoon with
showers lingering into Tuesday. Another re-enforincg shot of warm
and moist air will head to the western Bering and Western
Aleutians beginning Tuesday as another Kamchatka low, potentially
stronger than today`s eastern Bering low or Monday`s Bering low,
moves into the western Bering by then. Stay tuned for forecast
updates, especially regarding the development and track of the
Eastern Russian low that is poised to track through the Bering
Monday and Tuesday.

&&


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

Forecast models continue to favor a longwave trough over the
Bering, which keeps both Southwest Alaska and Southcentral Alaska
within southwesterly flow for the foreseeable future. This will
promote numerous opportunities for additional rainfall as each new
low pressure system or trough lifts through the interior. As
such, expect below normal temperatures to continue and above
normal precipitation chances through the end of next week.

-BL

&&

.AVIATION...

PANC...While VFR conditions are expected to persist, widespread
rain showers will continue, moving across west Anchorage,
including ANC. Light winds this morning will intensify to a gusty
southeast flow with a Turnagain Arm wind growing by the late
morning. Short periods of MVFR categories are possible at times
during bouts of heavier rain. Gusty winds over the terminal will
cut off by Sunday morning as the flow turns down-Inlet.

&&
$$