144
FXAK68 PAFC 181242
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
442 AM AKDT Fri Jul 18 2025

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

The underlying pattern is not slated to change much this weekend
as much of Southcentral continues to see a mix of clouds and sun
along with seasonably warm temperatures through early next week.
This morning, an upper level trough is moving from the Alaska
Peninsula up into the greater Cook Inlet and Mat-Su region,
spreading mostly mid to upper level cloud cover into all but the
Copper Basin. Farther south, a weak low is developing just south
of Kodiak Island along a slow moving frontal boundary lifting up
into the southern Gulf. Similar to the last system a couple days
ago, rain associated with the incoming front is very unlikely to
reach just about any part of the Southcentral interior.
Measurable rainfall will be confined mostly to the southern end
of the Kenai Peninsula and Kodiak Island today as the upper level
trough outruns the already weak Gulf low and front, which will
cause the system to dissipate and lose upper level support well
before it can make any headway past the Gulf coastline. Southerly
gap flow will develop out of the Copper River Valley and Turnagain
Arm today, but given the upper cloud cover and very weak coastal
gradient, expect gap winds in both locations to remain fairly
light today.

From Saturday into Sunday, the northern periphery of a Pacific
ridge will build into the southern Mainland, extending the already
relatively warm and dry conditions for much of the region. The fly
in the ointment hinges on the exact timing and trajectory of a
series of weak shortwaves that could eject from a large Bering
Sea low and ride around the ridge axis. Any stronger shortwave
that can reach our area will threaten to bring periods of light
rain at times for mainly the western half of Southcentral,
particularly towards Sunday afternoon. However, it`s quite
plausible that (just like what we observed with the past two
disturbances) precipitation will fail to make it much past the
Cook Inlet and Kenai Peninsula as supporting lift weakens while
the upper ridge remains the dominant influence on surface
conditions. Regardless of any rain chances, expect valley
temperatures to become quite warm both Saturday and Sunday, with
much of Anchorage and the Mat- Su Valleys approaching 70F for
highs. In fact, parts of the Copper Basin could even hit 80
degrees on Sunday afternoon.

-AS

&&


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

A quasi-stationary, occluded Bering Sea low located roughly 275
miles north of Amchitka will continue to steer multiple waves of
moisture and smaller low pressure systems into the Aleutians,
Alaska Peninsula and Southwest Mainland through the end of this
weekend. There is also a more compact low pressure system
skirting just to the south of the Aleutian chain. Aloft, the flow
around the Bering low is rather disorganized and noisy as multiple
vorticity waves are being advected from the North Pacific, across
the Aleutian chain, and into the Bering.

This morning, a fast moving low pressure system situated between
Chignik and Kodiak Island is quickly moving out of the region and
into the Gulf of Alaska. Showers are expected to continue for a
few more hours for the northern AK Pen and Kuskokwim Valley as the
system departs.

Due to the low formation south of the Central Aleutians, a stout
southerly wind fetch has developed and is moving across the
Eastern Aleutians, with small craft conditions expected for Dutch
Harbor and Cold Bay. Friday afternoon to Saturday evening,
southerly winds return for Bristol Bay as the low pressure system
and its front move eastward. There is the likelihood of a
prolonged period of onshore winds early Saturday afternoon through
the late evening hours for the Southwest Mainland coast. The
current thinking for precipitation is that an axis of moisture
will move inland into the Kuskokwim coast and Bristol Bay areas,
and then pushing more so into the Southwest interior on Saturday.
As this low departs Sunday, widespread showers are expected across
the Aleutians, Alaska Peninsula and Southwest Mainland.


-AM/DJ

&&

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

By Monday, the pattern will be initially directed largely by a
weakening low pressure system over the northwestern Bering Sea and
a large ridge developed over the southern Gulf of Alaska.
Southwesterly flow across southern Alaska will persist due to the
orientation of the aforementioned pressure system. This flow
pattern will keep Southwest Alaska likely moist with plenty of
cloud cover with air continuing to flow in from the Bering Sea.
Through mid-week, the weak low in the northwestern Bering will
dissolve, leading to the pattern being lead by the ridge in the
northern Pacific. Shortwaves coming up and over the ridge will
maintain the unsettled pattern along the Alaska Peninsula and into
Southwest/Southcentral mainland Alaska.

-CL

&&


.AVIATION...

PANC...VFR conditions will persist. Light winds this morning
become southeasterly with gusts of 15-20 kt this afternoon and
evening, then diminish overnight. Ceilings may drop to around
4000 ft early this morning but should increase above 5000 ft by
late morning.

&&


$$