349
FXAK67 PAJK 060004
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
404 PM AKDT Tue Aug 5 2025

.SHORT TERM...Mostly unchanged opinions for the short term
forecast, with an upper level low currently above Dixon Entrance
moving eastward. High pressure in the central gulf builds
tomorrow, bringing warm temperatures, clearing skies, and a marine
layer over the gulf waters. An easterly push of showers and slight
chance of thunderstorms is expected to move over the northern
panhandle this afternoon, with several thunderstorms already
developed on the Canadian side. NUCAPs soundings show a healthy
dry layer above 700 mb, with around 400 J/kg of DCAPE, which would
lead to some windy conditions as showers collapse. Not expecting
these to be long lasting showers as lack of significant shear,
around 25 knots, means that developed cells will be short lived.
Tomorrow, the increased heat will come, with aloft temperatures
around 850 mb approaching 11-12 degrees C, which translates to low
to mid 70s as a maximum in areas away from the water near sea
level with clearing skies.

.LONG TERM...
By Thursday a Rossby Wave will be the catalyst for the merger of
two systems; a broad closed low over the Bering Sea and the other,
remnants of Tropical Storm Krosa. As the parent low rotates over
the Alaskan Peninsula Thursday, an occluding front will move into
the Gulf bringing southeasterly gale force winds near Cape St.
Elias, with strong breezes (22 to 27 knots) anticipated for much
of the coast. Fresh southeast seas of 11 to 14 ft with a period
less than 10 seconds will dominate the wave energy spectrum with
underlying southwest swell. One item of uncertainty is theta-e
analysis indicating the formation of a triple point low late
Thursday along Haida Gwaii which could bring slightly higher winds
than forecasted.

Friday, the Tropical Depression Bailu will merge with the parent
low over the Alaska Peninsula, riding the southwest flow into the
Gulf, driving the weather through the weekend. Guidance continues
to struggle with placement of deep moisture given the current
entropy found in the west pacific; however, we have higher
confidence for heavy rain for the central and southern Panhandle
by Saturday/Sunday. The limiting factor again will be lack of
atmospheric forcing to efficiently drive the rainfall out; its
not a question of where it will rain but how much will it rain.

&&

.AVIATION.../Until 00Z Thursday/...Expect CIGS to continue to
improve into the VFR category for portions of the Icy Strait
Corridor(including Gustavus) & the NE Gulf Coast(including
Yakutat) through this afternoon, matching the current category of
the visibilities, as the upper level low currently impacting the
area continues to weaken & depart the area, moving southeastward.
A ridge of high pressure will build-in following that low for
Wednesday, bringing in more sunshine. Tonight, under the ridge,
clearing skies & lighter winds overnight are expected, giving some
areas of the Panhandle patchy FG with CIGs & VISs potentially
dipping into the IFR/MVFR category range. Through Wednesday, from
daytime heating, conditions will be right for sea breezes. SFC
wind and LLWS values look to remain benign through the TAF period.

&&

.MARINE...
Outside: Benign NW winds to 10 knots will increase with the
building of a surface ridge in the central gulf. Winds are
expected to cap at 20 knots with a slim chance of around 20% to
hit 25 knots SW of Prince of Wales Island. Along with the
increased winds, warm temperatures aloft with downward motion will
help develop a marine layer for the outside coast. Expect to see
widespread fog down to one mile visibility with pockets of dense
fog. More confidence on visibilities down to one mile than any
dense fog development over the water.

Inside: For the inside waters, expect to see another round of
radiation fog in calm wind areas overnight as skies clear. With
recent rainfall, relative humidities across the panhandle are
starting high with little dry air mixing in during the day today.
Therefore, it will not take much cooling for a low cloud/fog layer
to develop, particularly in areas where winds are calm. Luckily
for the main channels, the low pressure to the south looks to keep
winds mostly 10 knots or slightly greater from the north through
the night, which will limit fog changes over open water. However,
sheltered areas from northerly winds will likely have some fog
development overnight tonight.

&&

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

&&

$$

SHORT TERM...NC
LONG TERM....AP
AVIATION...JLC
MARINE...NC

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