793
FXAK67 PAJK 291840
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1040 AM AKDT Sun Jun 29 2025

.UPDATE...Updated aviation section for the 18z taf issuance and
hydrology section added for training showers over the Juneau area.

&&

SHORT TERM.../Through Sunday Night/...Sunday and Sunday night
are expected to be quieter, overall, though still somewhat damp
due to ongoing onshore flow. A new shortwave will target the
southern Panhandle by Sunday night. Winds should gradually weaken
throughout the day Sunday, with the strongest sustained winds up
to around 20 knots focused over northern Lynn Canal Sunday
morning. Scattered showers are likely during the afternoon. More
consistent rain and some wind will arrive late Sunday night in the
southern Panhandle as the shortwave moves into the southeastern
Gulf. However, this system will be weaker than earlier ones from
late week into the weekend, with maximum sustained winds of around
15 knots and lighter rain mainly affecting the southern Panhandle
late Sunday night.

LONG TERM...

Continued colder than normal temperatures, widespread overcast cloud
cover, and precipitation look to continue for the panhandle for the
foreseeable future. A cold upper level low will remain stationary
throughout the long term, at least through July 3rd, as the eastern
portion of an omega block over the entirety of Alaska. Much of the
large scale motions in the atmosphere over the state has good
confidence on occurrence. That being said, smaller details, that
being the various upper level troughs moving around the 500 mb low,
have much less confidence on timing, strength, and placement. What
is known into next week is chances for rain will broadly remain in
the forecast, with individual details still being worked out.

Highest confidence is in the Sunday forecast, with some mid level
ridging between 850-500 mb and drier air. While not to the levels
where clearing skies are expected, this will most likely result in a
break in rainfall for the northern panhandle, including Haines and
Skagway. Then, guidance continues to be uncomfortably divergent,
with global deterministic models settling on a slightly deepening
low moving in and becoming stationary approximately 30-50 NM off the
coast of Sitka. That being said, given the stronger solution, which
appears to be if the low strengthens off the coast of Sitka and then
becomes detached from the upper level flow, looks have two wraps,
with the initial as a warm occlusion with stratiform rain, and the
second convective. Deterministic CAMs that have this solution show a
line of convergence developing around southern Chatham Strait, lapse
rates exceeding 7 degrees C between 850-500mb, and a dry intrusion
from 700-500mb. While certainly not as intense as the middle of
June, gusty conditions could develop along this line of storms,
particularly if there are breaks in clouds ahead of this system. The
one caveat to this solution would be the convergence develops
somewhat early in the morning, which would limit any significant
surface heating and increased thetaE from any potential solar
radiation. Unfortunately for storm lovers, clusters particularly
within the EPS, and recent runs of CAMs lean towards a less
developed system, mostly cut off from any upper level shortwave
troughs. These solutions mostly impact Clarence Strait with an
increase in winds to 15-20 knots near the entrance to Dixon
Entrance, and mostly northerly winds in the inner channels. One
consistent feature of either solution though, is the tendency for
increased rain rates in northern Prince of Wales Island, Kuiu
Island, and Kupreanof Island near Petersburg. While not expecting
any flooding at this point for places like Falls Creek, drops in
visibility due to heavy rain are possible. In the official forecast,
went did not make many changes to the wind field except change many
areas in the inner channels to northerly, as places in the northern
half of the panhandle will be consistently northerly with either
solution.

Beyond Tuesday, confidence continues to be low, but what can be said
is persistent cloud cover and periods of rain will continue.
Ensemble guidance continues to show a low lingering over the Gulf
heading into next week. While there are no early indications that
this rain will be heavy, it does look to persist over the area.
Ensemble and NBM guidance for temperatures continues to show that
temperatures will around where they have been. But there is some
guidance trying to show signs of hope for mid week with increased
temperatures. Confidence right now in this solution is low at the
time of writing and leaned more on the continued wet pattern for the
time being.

AVIATION...This morning the panhandle is continuing to see a
mixed bag of flying conditions as the low in the Gulf continues to
bring onshore flow and convective showers. The majority of the
panhandle is going to continue to see largely MVFR conditions
today with some drops to low MVFR or IFR as showers move through,
and returning to more VFR and MVFR conditions once showers pass.
The southern and parts of the central panhandle will begin to see
improvements earlier today, expecting VFR conditions by midday
before the next wave moves into the southern panhandle by evening.
This will bring MVFR conditions to the panhandle as it moves
northward, with Ketchikan and along the southern coastline seeing
the highest confidence at having drops to IFR, with VIS dropping
to 4SM and CIGS falling to under 1000ft as the next shortwave
approaches. The northern panhandle and parts of the central
panhandle will hold onto MVFR conditions longer as CIGS are
expected to stay between 2000 and 3000 ft following showers moving
through, with Yakutat, Skagway and Haines seeing potential for
CIGS falling to under 1000 ft and conditions becoming IFR. Areas
in the central panhandle up through Icy Strait will begin clearing
up to VFR by the late evening, while Haines and Skagway are not
expected to improve to VFR until late at night.

Throughout the panhandle there is potential for fog later
tonight, which may bring some drops to VIS from VFR to MVFR for
areas that have improved in conditions.

MARINE...Outside Waters: A shortwave trough moving northwest
through the eastern Gulf early Sunday is generating southeast
winds up to about 20 knots near the northeastern Gulf Coast,
resulting in wind waves around 7 feet. A small southwest swell of
around 3 feet with a 9-second period is also present and should
persist through Monday. As the shortwave continues westward, it
will continue to weaken. For Sunday and Sunday night, winds are
generally expected to stay at or below 15 knots with seas under 6
feet, even as another shortwave moves into the southeastern Gulf
late Sunday night. Brief bursts of 20-knot winds are possible near
Prince of Wales Island late Sunday night into Monday due to a
nearby surface low/wave, but any stronger winds should be limited
to a small area.

Inside Waters: Sustained winds near 20 knots will be mainly
confined to northern Lynn Canal on Sunday morning. These Inner
Channel winds will ease by the afternoon and remain lighter
through Sunday night. However, in Clarence Strait and near Cape
Decision, winds will increase late Sunday night to around 15 to 20
knots as the new shortwave approaches from the south.

.HYDROLOGY...Showers began training over the Mendenhall Valley
around 9 am Sunday dropping at times moderate to heavy rainfall.
In response Auke Lake and Montana Creek started to rise through
Bankfull as soon as 10 am. Showers are expected to continue to
train over western Douglas Island and the Mendenhall Valley
through at least Sunday afternoon with the afore mentioned basins
likely reaching minor flood stage around 11 am or noon. A flood
advisory has been issued for both Montana Creek and Auke Lake
through at least Sunday evening in anticipation of both reaching
minor flood stage from these showers.

&&

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

&&

$$

SHORT TERM...JLC
LONG TERM....NC/SEF
AVIATION...Contino
MARINE...JLC
HYDROLOGY...EAL

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