306
FXAK67 PAJK 131416
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
616 AM AKDT Thu Aug 13 2026

.SYNOPSIS...

Key Messages:

- Suicide Basin is releasing. Major flood stage on Mendenhall Lake
  and River expected to be reached Thursday morning with a crest
  around midday Thursday.

- Very warm temperatures to end the work week with highs in the
  mid 70s to lower 80s.

- The warm and dry conditions will bring elevated threat for fire
  starts across much of SE AK. A few small fires have been
  observed already over the past week.

&&

.SHORT TERM...Warm and dry weather remains across the panhandle
through the end of the week with high pressure continuing to sit
over the Gulf. As this high continues to shift west today,
offshore flow will become more northeasterly, keeping widespread
clear skies across the panhandle through the day today and
Friday. This NE-ly flow will also allow for a drier and warmer
airmass to move into the panhandle from interior Canada, with
temperatures of 14 to 15C at 850 mb pushing into the area. This,
along with the clear skies, will allow many areas to see daytime
highs in the high 70s to low 80s, up to the mid 80s for some
isolated inland locations. Locations along the water may stay a
bit cooler today and tomorrow from sea breezes moderating the
temperatures, but many of these areas will still reach highs in
the mid to upper 70s before the afternoon sea breeze actually
develops.

Thursday and Friday afternoon and evening remain having a slight
chance for isolated thunderstorms for the far SE corner of the
panhandle and along the coastal mountains. The conditions remain
mostly present for thunderstorms to pop up in the Misty Fjords
area around Ketchikan, however the moisture at the lower levels is
still not high enough to have higher confidence at this time. Some
isolated thunderstorms approaching from the east in Canada look
more likely to remain east of the border, with only slight
chances of actually pushing into the Ketchikan and Hyder area and
even lower chances of anything moving into Clarence Strait and PoW
Island. These conditions will continue to be closely monitored in
case confidence increases for any convection making it into the
southern panhandle, as gusty winds and lightning are possible if
any thunderstorms move into the area and over the waters.

.LONG TERM.../Saturday onward/... Saturday looks to conclude our
period of temperatures that have the potential to reach heat
advisory criteria (80F), with 850mb temperatures expected to be
around 12C-13C, thus bringing high temperatures that are likely
to be in the mid to high 70s. Cloud cover on Saturday is expected
to be less than 25% in the morning and increase to over 50% in the
northern panhandle, which could impact the temperatures that are
currently forecasted. 850mb temperatures on Sunday are not
expected to be as warm, sitting around 10C which can still bring
temperatures in the 70s to the panhandle, but are not likely to
cause advisory level heat. Temperatures in the high 60s and low
70s are expected which marks the start of gradually cooling
temperatures through the week. The cause of the cooling temps is
due to a shift in the upper level flow to an onshore direction.
This shift will bring cooler, wetter air off the ocean which will
cause a shift in the dry weather pattern we have been
experiencing. This shift is expected to occur through the day
Sunday, bringing our usually scheduled program back to panhandle.
Rain is expected to arrive in Yakutat Sunday evening with the
greatest accumulations likely to occur early Monday morning, with
no more than 0.2 in falling in a 6 hour period. Rain will then
move south across the panhandle through the day Monday and is
likely to be showery and light in nature due to the low QPF
amounts that models are currently picking up. This pattern of
damper, cooler conditions is expecteted to last through most of
next week.

&&

.AVIATION...Very quiet aviation weather this morning with VFR
conditions panhandle wide with winds of 10 kt or less. Some ground
fog has developed in isolated areas like Yakutat, Gustavus, and
Klawock, but visibility restrictions are not anything more then
1.5 miles currently and should not last long once the sun rises.
Widespread VFR conditions expected for Thursday and proceeding
into Thursday night as offshore flow continues. Afternoon sea
breezes will still be a factor in some areas with winds up to 15
kt in some cases.

&&

.MARINE...
Outside: High pressure over the Gulf keeps a tighter
gradient over the eastern waters. Moderate to fresh breezes for the
outer coastal waters through Thursday night, with strongest winds
from near Cape Spencer down to Dixon Entrance this morning. Winds
will gradually diminish overnight into Friday, becoming a gentle to
moderate breeze that will remain into the weekend as the high
weakens and drifts west. Wave heights of 4 to 6 ft Thursday, with
waves up to 7 ft offshore from Cape Decision to Dixon Entrance in
the morning. Seas will diminish to 4 to 5 ft Friday into the
weekend. Main marine concern for outer and coastal waters will be
nightly return of marine layer, with fog and low stratus offshore.

Inside: High pressure out in the Gulf is expected to linger through
the end of the week. Moderate to fresh breezes for the inner
channels continue tonight through Thursday. Localized wind shifts
due to sea breezes are possible, alongside elevated gusts to 15-20
kt, but overall wind direction is expected to be from the NW.
Strongest inner channel winds up to 15 to 20 kts are expected for
the afternoon and evening hours. Winds across the inner channels
will will diminish Thursday night as high pressure weakens and
shifts west, relaxing the gradient across the panhandle. This will
also shift the NW-ly wind direction to be more from the N/NE by
Friday from low pressure sitting south of the panhandle. Light to
gentle winds are expected by Friday and should continue into the
weekend. N-ly winds of 15 to 20 kt are expected for northern Lynn
Canal through Friday from a tightened N-S gradient remaining
across the far northern panhandle.

Slight chances remain for isolated thunderstorm development from
Canada moving into the southern panhandle Thursday and Friday
afternoon/evening, primarily near Misty Fjords and Clarence
Strait. Gusty winds and lightning would be possible if any
thunderstorms make it into the area.

&&

.FIRE WEATHER...High pressure out the the Gulf continues to bring
mostly dry and warm weather across the panhandle. Warm
temperatures with daytime highs reaching the upper 70s to mid 80s
and dry weather are expected to continue through the end of the
week and into the weekend. More inland areas are expected to
continue reaching relative humidities down to the 30s to 40s
during the daytime hours with rebounding during the overnight
hours into the 80s to 90s. With the continued lack of rain, fine
fuels such as grasses will continue to dry.

Models continue to suggest the potential for isolated
thunderstorms along the Panhandle border with Canada as well as
the SE panhandle on Thursday and Friday during the
afternoon/evening. Low end chances remain for the same time
Saturday as well. However, due to the lack of low level moisture
each day the chance of thunderstorms is still only around 15% or
less.

Overall, expecting the dry and warm trend to continue through the
end of the week with fire weather conditions looking to last into
the weekend as well, however the main variable to watch for will
be daytime winds. As of now, expecting the worst fire weather
conditions to be Thursday and Friday afternoon, however given the
persistent pattern can`t rule out this extending further into the
weekend. The dry conditions are looking to last through the
weekend, with the next chance of rain not being until Monday.

&&

.HYDROLOGY.../Flood Warning in Effect/

Mendenhall Lake gauge levels, along with USGS imagery from Suicide
Basin and water levels within the basin, indicate that a glacial
lake outburst flood is ongoing into Mendenhall Lake and River.

From overnight, the river crossed into Minor Flood Stage of 9 ft
around 10:45pm before continuing to rise into Moderate Flood Stage
of 10ft around 1:30am. As of 5 am AKDT, the Mendenhall River and
remains in Moderate Flood Stage, currently reading 11.5 ft and
rising. Water levels on the Mendenhall Lake and River will rise
through the afternoon as the release continues, with a forecast
crest between 16.1 to 16.6 feet expected Thursday afternoon between
11 pm and 3 pm. Compared to previous years this is slightly below
last year`s high water mark, and above the high water marks of 2023
and 2024.

Visit weather.gov/ajk/SuicideBasin for the latest updates on the
Glacial Lake Outburst Flood for Mendenhall Lake and River. The
weather.gov/ajk/SuicideBasin web page is currently updated every two
hours by the NWS Juneau office and as we move further into the
event, this cadence will increase to hourly updates.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Heat Advisory until 7 PM AKDT Friday for AKZ318-319.
     Heat Advisory from noon today to 7 PM AKDT Friday for AKZ321-325-
     328-330>332.
MARINE...None.

&&

$$

SHORT TERM...Contino
LONG TERM...AGP
AVIATION...EAL
MARINE...Contino
HYDROLOGY...NM

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