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Southeast Alaska Forecast Discussion...UPDATED
National Weather Service Juneau AK
339 PM AKDT Thu Sep 4 2025

.SHORT TERM...Largely the same pattern today with the ridge
lingering in the central Gulf, alongside a weak surface low moving
up along the outer coast. This has enabled some moisture in the
form of a marine layer to form around the southern panahandle and move
from south to north into the central inner channels this morning.
This low will continue to move up along Baranof Island up to off
of the NE Gulf coast by tomorrow night, weakening before it
dissipates by Saturday morning. This will allow for more of the
marine layer formation tonight to move up into the central inner
channels, with the highest agreement being from southern Chatham
Strait up through Icy Strait. The majority of fog formation in the
inner channels will occur around and after 10Z tonight, and will
last into the morning with visibilities of one mile or less
possible over the water and some inland locations impacted by the
marine layer. Tomorrow night there will be less chances of
widespread fog formation, however some chances for precipitation
will begin to impact the NE Gulf coast tomorrow night. Any
rain will be light, and precipitation chances largely remain
between 10 and 30%. Much lower chances exist now for other parts
of the panhandle, with most areas having been brought down to less
than 15% PoPs for tomorrow night.

.LONG TERM.../Saturday through Thursday/ Overall upper level
pattern features a gradual shift away from the ridging that has
been keeping us dry, to more of a SW flow pattern over the Gulf of
Alaska and SE as a broad upper trough settles over the Bering Sea
area by next week. For SE this means a trend toward cooler,
cloudier, and damper weather.

At the surface, this trend toward cooler and damper will be aided
by two systems that will be moving into the gulf from the west.
The first is a low that will be moving in from the Bering Sea on
Sunday into Monday. Some uncertainty on how far east it will get
before the residual ridge in the gulf and panhandle tears it
apart. Yakutat is the most likely place to see light rain out of
this feature Sunday night, but I can`t completely rule out some
light rain getting as far east as the central panhandle on Monday.
At the very least, increased cloud cover will be the main effect
as this feature moves through. System number two is the effects
that we will see from a rather potent Bering Sea low mid next week
that has some tropical influences. Guidance is having some
trouble pinning down where this system will be heading, but
confidence is growing on the front that it sends across the gulf
Wed into Thu increasing winds across the gulf (to around 20 to 30
kt) and bringing some wetting rain to the area.

Throughout all of this, temperatures will be cooling. Highs by
mid next week will likely be widespread 60s with lows in the upper
40s to mid 50s for most areas. These values are still a few
degrees above normal for this time of year, but are not the near
record warmth that the panhandle has been seeing the last few
days.

&&

.AVIATION...The marine layer is beginning to push northward,
bringing LIFR to IFR CIGs and VIS all the way up to Angoon. This
layer will begin to battle the sea breezes already beginning to
develop in Gustavus and Juneau. Said sea breezes are currently
expected to cause turbulent mixing, effectively blocking the
northward expanse of the low cloud deck. Therefore, keeping
Gustavus & Juneau northward as VFR through the day today. Further
in the inner channels, particularly around Petersburg, has mostly
only received parts of the marine layer. As this marine layer is
driven by a mesoscale low in the gulf, mountain will largely
continue to shield Petersburg from the bulk of the low clouds.

Currently expecting Ketchikan to clear sooner, as southerly winds
aloft shift to northwesterly from the departing low pressure to
the north.

Expecting to see a resurgence of a marine layer to the same areas,
but this time including Gustavus and Juneau tonight. Widespread
LIFR CIGs will spread over a majority of the panhandle beginning
early tonight. Expecting the central panhandle, including areas
from Wrangell to Angoon to receive a bulk of the fog, with areas
near Clarence Strait raise to a low cloud deck.

&&

.MARINE...
Inside Waters: Largely expecting lighter winds around or below 10
kts across the inner channels for tonight. The main areas of
exception will be southern Clarence Strait as northwesterly winds
strengthen to up to 15 kt going into Dixon Entrance, and in
northern Lynn Canal increasing to between 10 and 15 kt this
evening. Winds across the inner channels will decrease into later
tonight through tomorrow morning, with Clarence Strait staying at
between 10 to 15 kt as ridging lasts southwest of Haida Gwaii.
Winds will increase again into tomorrow afternoon and evening as a
ridge strengthens again offshore and a low strengthens to the
northeast over Canada, increasing the pressure gradient across
the northern channels, particularly around Point Couverden and
northern Lynn Canal.

Outside Waters: As a weak low travels northwest along the Gulf
coast, winds will remain below 15 kts with the majority of the
Gulf seeing calmer conditions through tonight. The majority of the
10 to 15 kt winds will be along the west of POW moving into Dixon
Entrance, which will begin to see winds increasing tonight and
tomorrow from a ridge to the southwest of Haida Gwaii funneling
winds from the W and NW into Dixon Entrance. Largely expecting 4
to 6 ft wave heights across the Gulf tonight and tomorrow, with a
westerly swell of 3 to 4 ft tonight into tomorrow. Dominant wave
period for tonight and tomorrow will be between 11 to 15 seconds.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

$$

SHORT TERM...Contino
LONG TERM...EAL
AVIATION...NC
MARINE...Contino

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