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AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
413 AM AKDT Wed Jul 9 2025

.SHORT TERM.../Today and Tonight/
Key messages:
- Land and inner channel marine winds remain around 15kts or less
  through Wednesday, strongest winds in Cross Sound and S Lynn
  Canal north to Taiya Inlet near 20kts in the afternoon.
- Showers diminish in coverage through the afternoon with partly
  sunny skies by Wednesday evening.
- High temperatures in the upper 50s to low 60s, low temperatures
  in the upper 40s to low 50s.
- Gale force system arrives in the Gulf and into the Gulf coast
  late Wednesday night into early Thursday morning.

Discussion:
No significant changes to the short term forecast this morning as
residual open surface trough and upper lvl low continue eastward
into British Columbia/Yukon. Anticipating overcast skies and
showers this morning to become more isolated through the afternoon
under partly sunny skies as a brief bout of surface ridging
pushes over the panhandle. Winds under the ridge will remain
rather benign outside of sea breeze events, around 15kts or less,
with usual suspects like Lynn Canal and Cross sound overperforming
up to 20kts through Wednesday afternoon. Needless to say, no
significant hazards expected through Wednesday.

Next impactful event will be a gale force front pushing into the
Gulf waters late Wednesday night into early Thursday morning.
Expecting southeasterly winds to increase to 35kts and seas
increasing to 10 to 13ft over the Gulf by 6am Thursday. For more
information on this system, please see the Long Term discussion
below.

.LONG TERM.../Thursday through Tuesday/
Key messages:
- Atmospheric river brings moderate to heavy rain Thursday
- Gale force winds along the NE coast and near Dixon Entrance

Details: The main long term impact will be the atmospheric river
funneling moisture into the panhandle Thursday into Friday. The
ridge over the panhandle will continue getting pushed eastward by
a surface low pressure system with an upper level low in the
western gulf. With the help of the upper level jet, the associated
warm front will reach the panhandle through late Thursday
morning, fueled by a large plume of increased moisture from a
moderate atmospheric river. This system is expected to bring
widespread moderate to heavy precipitation through Thursday
afternoon. Highest rates will occur Thursday night into early
Friday morning, with a majority of areas (mostly in the southern
panhandle or along the coast) seeing potential for 1.5 to 2 inches
of rain in this period.

Sustained gale force winds of 35 to 40 kts are expected toward
the NE gulf with the strongest winds off the coast of Cape
Yakataga. The rest of the eastern gulf coast will still see
increased winds to strong breezes of 25 to 30 kts along the
outside marine waters. Inner channels winds increase up to 30 kts
with the strongest at ocean entrances and in Clarence Strait near
Dixon Entrance. Land areas in the southern panhandle and off the
coast of Yakutat could experience wind gusts around 35 mph.

Confidence continues to increase in the strength of the AR with
multiple IVT ensembles showing the likelihood of a magnitude of
>500 kg/m/s of integrated water vapor transport, a moderate
atmospheric river, moving over the panhandle. EFIs are indicating
a high QPF potential for the southern panhandle with a shift of
tails of 2. NBM guidance is indicating much higher amounts of
precipitation than initially expected, leading the decision to
increase amounts for areas of the southern panhandle to >0.5
inches of rain in 6 hours. In 24 hours, areas across the panhandle
will receive 1 to 2 inches of rain, with southern Baranof Island
and higher elevations receiving up to 3 inches. Currently, no
flooding impacts are expected, but increased snow levels with
heavy rain rates can lead to rises in rivers and creeks to bank
full.

Active weather continues for SE AK into next weekend as onshore
flow with a few embedded shortwaves keep the panhandle damp. Stay
tuned as we will continue to update the forecast ahead of this
system.

&&

.AVIATION...Primarily MVFR to VFR flight conditions this morning
across the panhandle, although low stratus decks in a few areas
have seen ceilings approaching IFR. Through the morning hours,
conditions will broadly improve across the board as the remnants
of a system over the area disintegrate entirely, leaving behind
some occasional showers, alongside breaks in the cloud deck. Winds
will remain around 10 kt or less for most locations with the
occasional isolated gust. The exception to this will be areas
around northern Lynn Canal, notably Skagway, which will see
sustained winds approaching 20 kt, and gusts approaching 30 kt.

Conditions significantly deteriorate Thursday as a gale force
system moves into the panhandle, bringing periods of heavy rain
and windy conditions across the area.

&&

.MARINE...
Inside waters: High pressure will build in from the south through
Wednesday. The ridge will be quite flat for the next 24hrs,
leading to a general W wind, which means some of the N-S passage
wind directions will want to kink either NW or SW, or just be
variable <10kt. The ridge looks to sharpen over the eastern gulf
through Wednesday afternoon, causing NWLY winds to be preferred on
the lee side of the ridge axis for (Clarence Strait). Sunny
breaks will enhance sea breeze winds in the afternoon and early
evening, likeliest locations along the central and southern
panhandle.

Outside waters: Generally west winds of around 15 kt and some
higher gusts in dissipating showers. Seas this morning remain on
the low end with gulf buoys reporting 3 - 4 ft combined seas and a
S swell with around a 15 second period. Expect seas up to 3-5ft
to persist through the day until a strong front approaches the
outer Gulf waters by late Wednesday night. Anticipating winds will
increase to gale force (+35kt) by Thursday morning over the Gulf
with strongest winds contained along the northern Gulf coast with
barrier jet formation by Thursday afternoon.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ652-664-671-672.

&&

$$

SHORT TERM...NM
LONG TERM....STJ
AVIATION...GFS
MARINE...STJ/NM

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