093
FXAK68 PAFC 171313
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
513 AM AKDT Mon Aug 17 2026

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

Key message:

* Flood Watch is now in effect for the Susitna Valley for areas
  upstream of Lake Creek and Yentna Rivers through Wednesday
  afternoon. Rainfall totals of 2 to 4 inches expected. Near the
  Parks Highway, from Willow through Talkeetna, 1 to 2 inches of
  rainfall expected.

Discussion:

The large low that has been tracking through the Bering Sea is now
in Southwest Alaska. The main front associated with it has swept
through Southcentral and is in the Interior of the state as of
early this morning. The result is that there are strong pressure
rises behind this front that are spurring gusty southerly winds
up Cook Inlet and also though the Copper River Basin gap areas.
Southcentral is also in the showery sector of the low with
multiple shortwaves kicking off periods of showers. Throughout the
day there should be a slow diminishing of both the winds and in
shower activity for most of the area. The Susitna Valley is the
one region that will likely really hold onto the rainfall as the
south-to-southwest flow aloft is favorable for upsloping along the
Alaska Range and Talkeetna Mountains. In addition, the Susitna
Valley is closer to the upper low center which is keeping it more
unstable as well. This is a major reason there is a Flood Watch
in effect for some portions of the Susitna Valley.

By Tuesday, the upper level low will ave tracked northeastward
though the Interior. However, as it usually the case in August,
the large longwave trough remains over the Bering Sea and another
upper level low embedded in this trough is ready to replace the
old low. This will allow less shower activity for tuesday as the
second low is sill out in the Bering Sea, but by Wednesday it
should be moving into Bristol Bay and bring more widespread
rainfall into Southcentral.

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(Days 1 through 3: Monday through Thursday afternoon)...

An active pattern continues across Southwest Alaska, the Bering
Sea and Aleutians through the middle of the week as a series of
upper-level disturbances track across the region. A compact upper-
level low near the Alaska Peninsula and eastern Aleutians today
will gradually lift north and east, while another upper- level low
approaches the western Aleutians from the North Pacific.

For today, the upper low near the Alaska Peninsula (AKPEN) will
continue to support areas of rain and gusty winds across portions
of Southwest Alaska, the eastern Aleutians and AKPEN. Farther
west, the next system approaches the western Aleutians, with
increasing winds and rain spreading into the region.

By Tuesday, the first upper low begins to weaken as it lifts
farther into Southwest Alaska, while the western Aleutian system
becomes the more dominant feature. This low and its associated
front will progress eastward along the Aleutian Chain, bringing
another round of rain and gusty winds from west to east. Periods
of low clouds and fog will also remain possible across the Bering
and Aleutians.

Wednesday into Thursday, the upper low continues eastward toward
the eastern Aleutians and AKPEN. This will maintain unsettled
conditions across much of the Aleutians and southern Bering , with
rain and gusty winds gradually shifting east. Increasing chances
for precipitation will spread toward Bristol Bay and portions of
Southwest Alaska as the system approaches. Model agreement
decreases somewhat with the exact position and strength of the low
later Wednesday into Thursday, the overall pattern favors
continued unsettled conditions through the end of the period.

LM


&&


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

The long-term period starts with an upper-level low situated over
Bristol Bay and a surface low over the Alaska Peninsula or
extreme western Gulf of Alaska. These features will bring rain
across the Southern Mainland through Thursday.

A stronger and potentially more impactful storm for Friday and
the weekend across the Southern Mainland begins to take shape
upstream in Kamchatka Thursday. A strong shortwave digs south from
Siberia to the northern Bering Sea by Friday morning. A gale-
force surface low Will move into the northern Bering around St.
Matthew Island to St. Lawrence Island by Friday morning. Moderate
to heavy rain is likely to overspread the Southern Mainland,
starting first with Southwest on Friday, and working east to
Southcentral through Saturday. Showers continue across the
Southern Mainland on Sunday as the low works farther into Western
Alaska.

Trends with this system, deviations in track and strength, will
have to be watched closely when it comes to determining coastal
impacts along the Kuskokwim Delta Coast. Taking a quick look at
ensemble data, the GFS and Canadian ensemble suites are more
in line with each other with a slower and stronger solution. The
European ensemble guidance is a little faster with the storm track
which has the system moving inland of Western Alaska by Friday;
this solution also features a weak system. Regardless, there will
be a push of on-shore flow with this system, it will be a matter
of its magnitude which will be ironed out in due time.

Farther out west, embedded shortwaves moving from west to east
atop a strong North Pacific ridge will keep the Aleutian Chain
showery at times for Thursday. The northern Bering low`s front
will also sweep across the Chain for Friday and make it to the
Alaska Peninsula (AKPEN) for Friday night into Saturday. The
southern AKPEN will see the wettest conditions with this front
Friday night into Saturday as it only grazes the Aleutian Chain
Friday. The AKPEN will remain showery for Saturday and Sunday as
flow turns northerly behind the northern Bering low which is
moving inland by then. A surface ridge works in across the Central
and Eastern Aleutians Saturday and Sunday as shortwave and
another round of showers approaches the Western Aleutians from the
North Pacific.

&&


.AVIATION...

PANC...VFR conditions are expected to remain through the TAF
period, though periods of showers may causing ceilings to dip to
MVFR at times. Gusty southerly winds will persist through the day
and start to diminish some overnight. As the surface winds and
winds aloft are both from the south, low level wind shear is no
longer expected.

&&

$$