807
FXAK67 PAJK 111735
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
935 AM AKDT Mon Aug 11 2025

.UPDATE...Update to the aviation section to include the 18z TAFs
and added a Hydrology section to include the Mendenhall GLOF
update.

&&

.SHORT TERM...

Heavier rain looks to be moving into the panhandle shortly.
Checking out MIRS rain rate product, a swathe of rain rates around
0.20 to 0.25 in/hr from Yakutat to Cape Spencer is moving east
into the panhandle. Still expecting Baranof Island to take the
brunt of this moisture, with Gustavus, Hoonah, and Juneau
receiving the brief, upper portion of the moisture. As an upper
level trough advecting colder and drier air pushes in from the NW,
expecting the stream of moisture to shift southward and exit by
this evening. Currently have the QPF forecast unchanged, and based
on current observations, no significant changes are expected to be
made.

Looking towards Tuesday, the upper level trough will have
successfully pushed out moisture from the area, clearing skies
and inviting warmer temperatures. 850 mb temperatures around 9
degrees Celsius, typical with the cooler air advected over the
panhandle, look to increase highs for the upper 2/3 of the
panhandle to a maximum of the low 70s.

.LONG TERM...

Key messages:
- Light an diminishes as a Ridge builds in the gulf on Tuesday. This
  allows for drier conditions for the midweek.
- Winds diminish throughout the inner channels and are expected to
  remain light into Thursday.
- Rain returns Thursday into the weekend as another low pressure
  system moves throught the gulf.

Details: Times of light rain will continue into Tuesday morning
before an upper level ridge brings drier air toward the panhandle.
This drier pattern is expected to remain through Wednesday into
early Thursday morning. A decrease in moisture through the
atmosphere will in turn decrease cloud cover starting Tuesday. In
response, day time temperatures will increase to high 60s to low 70s
across the panhandle.

On Thursday into the weekend, a change in pattern occurs once again,
as an upper level trough and surface low pressure system moves
toward the panhandle. Associated with the surface low a front will
move over the panhandle once again bringing widespread rain.
Currently no significant rain amounts are expected with around a 60%
to 70% chance of greater than 0.5 inches of rain in 24 hours from
Friday into Saturday. The greatest precipitation totals are expected
along southern areas due to the track of the low.

&&

.AVIATION...Fairly widespread IFR to MVFR conditions, with isolated
LIFR conditions. Ceilings of 500 to 3000 feet are found across the
panhandle. The rain has been causing visibilities to fluctuate
between 1 and 6+ miles, with the lowest visibilities caused by
heavier rain rates or localized fog.

This band of heavier rain will move south through the panhandle
through the day, exiting northern SE AK by around midday, exiting
central SE AK by late afternoon, and exiting southern SE AK late
this evening. As the band of rain moves south today, expect some
improvement in conditions, although fog may develop Monday night
into Tuesday morning if clouds can clear out enough.

Expecting LLWS for central and southern panhandle sites through 00z
Monday with this front with strongest LLWS around 25 to 35kts for
TAF sites along and south of a line from Sitka to Petersburg through
Monday morning.

By late Monday night, the front will have departed, giving a chance
for clearing skies, and with them, the potential for fog
development. With the exception of the isolated fog, VFR conditions
will move from north to south beginning late tonight with VFR
lasting into Tuesday.

&&

.MARINE...
Outside: A warm front has successfully pushed into the panhandle,
increasing winds south of Sitka to a fresh breeze from the
southwest. Wave heights have been tamed somewhat with the relaxed
swell, with buoy 46184 reporting heights just under 7 ft. Looking
to see these heights increase slightly during the morning hours
to 8 ft with the consistent 20 knots, then diminish in the
evening. As ridging builds Tuesday, look to see winds to shift to
the NW continuing strong at a fresh breeze south of Sitka.

Inside: Stronger winds are building in the inner channels from
another low pressure system pushing into the NE gulf coast, and is
expected to redevelop in Canada. This is expected to be very
similar to yesterday morning, with Cross Sound starting out as
easterly, then as the low jumps inland, a burst of SW winds into
Icy Strait this evening. Beyond Monday night, clearing skies and
westerly flow will keep east west channels heightened. Not
expecting any marine layer to develop during the day in the outer
coast, limiting the thermal gradient influences in common areas
like Icy Strait and Peril Strait. Earliest chances of development
will be later in the afternoon and evening time frame, which may
keep westerlies elevated into the night, but confidence is low at
this time.

&&

.HYDROLOGY...As of 7:30 AM Monday, the USGS web camera and laser
gage in Suicide Basin continue to show indications of over-
topping. This means the basin is at full capacity. In the past it
has taken up to 6 days for the outburst flooding event to begin.

The water level in the basin will slowly fall as the overflow
channel erodes. A faster drop in water levels in the basin along
with a rise on Mendenhall Lake will indicate a sub-glacier release
and our office will issue a Flood Warning. From that point, the
outburst flooding event would take about 48 hours to peak.

Now is the time to finish up the flood preparation/planning and get
those plans "SET" so they can be put into action, and "GO" when a
Flood Warning is issued. Check back regularly for updates on this
evolving situation.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ641>644-661>664.

&&

$$

SHORT TERM...NC
LONG TERM...EAB
AVIATION...GJS
MARINE...NC
HYDROLOGY...GJS

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