796
FXAK68 PAFC 121326
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
526 AM AKDT Tue Aug 12 2025

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

Discussion:

High pressure will begin to shift east towards the ALCAN border
today then into western Canada by tomorrow morning. Western
Southcentral will see a bit more cloud cover today as a weak
shortwave trough tracks along the backside of the ridge. The Copper
Basin should see another nice mostly sunny day with temperatures
warming to into the lower 70s for the lower valleys. Elsewhere,
across Southcentral temperatures will be near normal with readings
in the 60s and 70s for inland valleys. While lower elevations of
more inland areas should remain warm and dry today, coastal areas
will see temperatures in the mid 50s to lower 60s and a smattering
of showers developing by this evening.

Wednesday and Thursday will see several shortwave troughs progress
across the Bering and Aleutian Chain before moving into
Southcentral. This series of disturbances will bring increased
chances for precipitation to first Kodiak Island and western half of
Southcentral, then progressing into the Copper Basin. The NAM is the
most robust precipitation maker...at least early on...with the GFS
becoming more robust heading into Thursday. This is most likely due
to the NAM developing a slightly stronger surface low near Kodiak
Island and deeper mid-level trough. As such, have stuck with a blend
of the GFS and NAM for now with the forecast being refined as
details begin to better take shape.

- PP

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(Tuesday through Thursday)...

Visibility across the Aleutians varies between one statute mile to
over 6 statue miles as the effects from an elongated front moving
through the area bring rain, mist and fog to the region. Rainfall
amounts over the past 12 hours is a few hundredths of an inch;
greatest in the Aleutians.

This front will continue to push across the Aleutians though
separate this morning bringing a period of dry or light rain to
the Alaska Peninsula / the far eastern Aleutians. Rainfall amounts
will range from a trace to a few hundredths as of 5:00am today;
highest in the Western Aleutians. The heaviest rain will move
northeastward into the Norton Sound area as the parent Bering Low
moves toward the Bering Strait today. The second area of
precipitation moving across the Central Aleutians this morning
arrives at the Southwest coast late this morning bringing rain
and southerly to southwesterly winds. These onshore winds will
allow increased water levels during high tide to minimal impacts
are possible into late this evening. A high surf advisory remains
in effect through late this evening for Togiak northward.Gap winds
will be strong the next few days. High pressure builds into the
region Thursday resulting drying conditions and an increased
chance for fog.


-DJ

&&

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

By Friday, upper level troughing will stretch across the central
and eastern two thirds of the state from the Arctic to the
southeast Panhandle. High pressure ridging will continue to build
over the Aleutians and Southwest Alaska, likely plaguing the
Bering Sea with some fog and low stratus. The tightening pressure
gradient over the Alaska Peninsula will produce gusty northerly
gap winds through favorable bays and and passes Friday and
Saturday.

Rain showers may linger across Southcentral on Friday as a
shortwave moves across the state and gets pulled into the Gulf. A
drying trend is expected to commence with generally quiet weather
through the weekend. A trough moving over the Aleutian Chain this
weekend could bring showers and enhanced winds, but this feature
looks progressive and move through quickly. Overall, look forward
to a generally settled weather pattern across southern Alaska.


&&

.AVIATION...

PANC...VFR conditions with light wind are expected to persist
through the period.

&&


$$

194
FXAK67 PAJK 121320
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
520 AM AKDT Tue Aug 12 2025

.SHORT TERM...

Longwave upper level trough is currently dig south, dragging
any remaining precipitation along with it. Embedded within the
trough at the vorticity maximum, strong WSW flow streaming
directly into Mendenhall Valley in Juneau has lead to enhanced,
terrain induced convective rain showers tonight. Dry, NW flow
aloft has begun to move into the Juneau area, marking the end of
the rain this morning. Comparing this to Lynn Canal, which is
currently experiencing breaks in clouds, shows what is in store
for the rest of the panhandle as this trough continues to move
south. Some low clouds and fog down to one quarter mile are
present along the northern panhandle and NE gulf coast, but are
expected to clear by 10 AM this morning with both solar radiation
and increased northerly winds from rising pressure in Canada.
Needless to say, with the sun`s rising, most of the cloud cover
north of the trough is expected to dissipate, leaving mostly clear
skies and temperatures reaching the upper 60s to low 70s across
the panhandle.

.LONG TERM...

For the start of the long term period, high pressure
continues to remain over the eastern Gulf Wednesday morning. This
high pressure will allow for a continued break from the rain
across the panhandle. With partly to mostly cloudy skies,
temperatures will be able to warm up somewhat during the day on
Wednesday.

This break in the clouds will be short though as the
clouds move back in for Thursday ahead of our next system that is
expected to impact the area late Thursday. An upper level trough
with associated low pressure will move SW of Prince of Wales and
become vertically stacked, bringing multiple waves to the southern
panhandle. One change is keeping the northern half of the
panhandle drier with NE Canadian air. That is until enough warm
air advection moves into British Columbia, forming a deformation
band. Then, moisture looks to get wrapped up in the easterly flow
and move over the northern half of the panhandle.

Accumulation amounts continue to look to be on the lighter side
until Friday when heavier precip moves in. This heavier precip
looks to be more focused on the southern panhandle approximately
from Sitka to Kake southward at the moment while places north of
there are expected to stay on the lighter side. Winds are expected
to increase Thursday night into Friday morning as well with most
places along the outer coast seeing winds range from 10 - 20 kt at
the time of writing. Through the Inner Channels, winds could be
up to 10 - 15 kt during this time. This will need to be monitored
as we head into the middle of the week for any potential changes.

&&

.AVIATION...
Better flight weather is on the horizon across SE AK after
Tuesday morning - though fog development later on during Tuesday
night could prove to be the fly in the ointment. Fog and low
stratus which formed during the early morning hours in the wake
of a departing system across some locations will dissipate through
the morning hours. Conditions will thereafter improve from North
to South in the wake of the system, with IFR and MVFR conditions
giving way to VFR for the northern panhandle through the morning
hours, and for the southern panhandle by the late afternoon
through evening time frame.

As clearing occurs, some locations are expected to develop
widespread fog or low stratus decks Tuesday night through
Wednesday morning. Areas where fog does develop should expect
significantly reduced visibilities and ceilings, both of which
could plummet back to IFR/LIFR for these areas until after sunrise
Wednesday morning, at which point daytime heating will see the
fog lift and dissipate, with dry weather expected through the day
on Wednesday for most areas, though a marine layer may linger for
some time in the morning along the outer coast.

&&

.MARINE...

Outside: With rising pressures in the northern and central gulf,
and a trough digging southeast through today, look for an increase
in NW winds, particularly this afternoon and overnight to a
moderate to fresh breeze. With very light SW swell, expecting
wave heights to be maximized this morning and slightly diminish by
this afternoon. Tonight will see a marine layer begin to develop,
bringing low clouds and dropping visibilities down to one mile,
particularly near Cape Spencer.


Inside: With the trough digging south to southeast and a ridge
building north and west of the panhandle, this has lead to a
mostly light to northerly wind pattern for the inside waters for
Tuesday. Several locations look to be impacted with increased
winds as the trough digs, mainly east west channels. Icy Strait
and Cross Sound, in particular, will have increasing winds from a
tightening gradient to 15 to possibly 20 knots later this morning
into this evening. Similarly, eastern Frederick Sound zone just
north of Petersburg and Sumner Strait look to see a brief increase
in westerly winds to a moderate breeze.

&&

.HYDROLOGY...

SUICIDE BASIN IS OVERTOPPING AND NOT RELEASING AT THIS TIME

Terrain induced, convective showers for Mendenhall Valley
overnight combined with Suicide Basin overtopping has lead to
Mendenhall Lake and River reaching minor flood stage. Based on
drier NW flow moving over the Juneau area, indicated by the blue
sky currently present at the Lena Point FAA camera, not expecting
Mendenhall Lake and River to pass approximately 9.3 ft.


&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Dense Fog Advisory until 10 AM AKDT this morning for AKZ317.
MARINE...None.

&&

$$

SHORT TERM...NC
LONG TERM...NC/SF
AVIATION...GFS
MARINE...NC
HYDROLOGY...NC

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