Elfin Cove Seaplane, Alaska Weather Forecast Discussion

837
FXAK67 PAJK 091815
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1015 AM AKDT Tue Sep 9 2025
.UPDATE...Update to aviation section to include the 18z TAFs.
&&
.SHORT TERM.../Through Tuesday night/
No major changes to the short range forecast overnight as SE AK
sees a shift to a more active and wetter pattern heading into mid
week. Rainfall from the first of two systems spread over the rest
of the northern panhandle overnight Monday and into this morning,
with only Juneau and Kake still reporting rain as of 6am. Not
expecting much more in the way of rain through the day today as
the first system continues to diminish and push inland. Little in
the way of wind with this feature as well, with areas reaching 20
kt at most for the gulf waters and some select areas of the inner
channels (like northern Lynn Canal and near Point Couverden this
morning). Southern panhandle will largely miss this system due to
the residual ridge over the panhandle tearing the front apart as
it comes, but will still see increased cloud cover from it.
The main focus of the forecast continues to be the strong system
incoming Tuesday night into Wednesday. The main low center will
stay relegated to the western gulf, but it will still send a gale
force front into the eastern gulf and panhandle by late tonight.
Winds in the gulf will start increasing as early as this
afternoon and will likely reach gale force around Cape Suckling
around Tuesday evening. Other areas of the NE gulf will see gale
force winds through Tuesday night, and the northern inner channels
will start to see wind increases by late tonight. Rainfall will
just be starting up along the NE gulf coast around midnight and
will spread into the northern panhandle by late tonight. Not a
lot of rainfall will have accumulated by late tonight, but rates
will be increasing into Wednesday morning.
.LONG TERM.../Wednesday through Sunday/...
Key Messages:
- A gale force front moves into the eastern Gulf
- Around 2 to 3 inches of rain expected in 48 hours, with select
  areas seeing closer to 6 inches
- Inner channel winds will pick up to 15 to 25 kts and slowly
  decrease through Thursday
Details: A deepening upper level trough is directing a near 980mb
low along the western coast of the gulf, sending a gale force
front to the outer coast of the panhandle Tuesday night. This
system, stemming from the remnants of a tropical system from the
northern Pacific, will help to direct warm and wet southwest flow
into the panhandle for the remainder of the week. Sustained wind
speeds along the eastern gulf coast are expected to reach 35 to 40
kts overnight into Wednesday morning, decreasing as the front
moves inland, but still remaining between 20 to 25 kts in the gulf
until Friday. Inner channels can expect SSE winds to start
picking up to 15 to 25 kts Wednesday morning as the front
approaches, with 25 to 30 kt winds possible for channel entrances
and peaking Wednesday night. An MWS has been issued for strong
winds and high wave heights for the outer coastal waters.
Rainfall associated with this system will be significant,
especially given the partial tropical origins and sub-tropical
moisture connection feeding the incoming front. Yakutat will
receive the brunt of this system, toting a heavy rain hazard for
Wednesday into Thursday. Precipitation is expected to push into
the panhandle early Wednesday morning. Areas north of Cape
Decision will see the heaviest rain and highest accumulations
Wednesday, with between 2.5 to 4.5 inches expected for many
communities. The southern panhandle will see most of the impacts
on Thursday with between 2 and 3 inches expected. Yakutat,
downtown Juneau, and higher elevated areas are an exception to
this, as they are currently looking to receive between 5 and 6
inches in 48 hours, with a majority of this falling on Wednesday.
An SPS has been issued in preparation for potential river rises
associated with the increased precipitation. It is also important
to note that with the last 2 weeks of abnormally dry weather, low
river heights and dry ground conditions may make flooding more
prominent. Damp weather persists into the weekend with wet SSW
flow continuing to funnel into the panhandle.
Temperatures will be near to somewhat above normal for this time
of year with highs reaching the 60s from the southerly flow
bringing in a warm and moist airmass for the next week.
&&
.AVIATION...The aviation weather story could be broken up into two
parts: The "now to late this evening" time frame and "overnight
into tomorrow" time frame. These differences are split around the
incoming gale force front expected tonight.
For the first time frame, now to late this evening to around the
04z to 09z window. At the 500mb level is a quick moving ridge of
high pressure. At the surface, the far northern edge of a ridge of
high pressure, centered way down in the central Pacific, will
move east into Canada. At the same time, the incoming front will
slowly tighten the pressure gradient over SE AK.
This pattern would generally give improving flying weather
conditions. So for those areas stuck under MVFR conditions due to
CIGs around 1500 to 3000 feet should see improving CIG this morning
with VFR expected by midday. And those VFR conditions should last
through the afternoon. Biggest wind concerns for today are centered
around Northern Lynn Canal, especially Skagway.
For the second half, with a transition period around 04z to 09z,
that is when conditions will deteriorate due to the expected gale
force front. As the front moves in, VFR conditions will lower to
MVFR for the northern half of the panhandle. IFR conditions are
possible beginning around 09z to 12z for scattered spots around the
northern half.
For those areas in the southern half, as the front tracks through,
some lowering is possible but at this point, the biggest impacts
would be to areas along the coast were MVFR is likely. Farther
inland, high-end MVFR would be worst case scenario.
Another aviation impact will be LLWS. As the front swings through,
LLWS will swing through as well. Impacts will begin in the Yakutat
area as early as 04 to 06z but the rest of the northern panhandle
will more likely see the LLWS move in around 09 to 12z. Higher east
to southeasterly winds will be around the 1000 to 2000 foot levels
at around 30 to 40 knots. Stronger winds possible in Yakutat.
The southern half could see some light LLWS late tonight into early
tomorrow, after 18z. Will reassess and consider LLWS for the southern
areas for the 00z TAF issuance.
&&
.MARINE...
Inside Channels: Low southerly winds of 10 kt or less are the
current conditions across a majority of the inner channels
Tuesday morning. The exception to this is Lynn Canal where
southerly winds up to 20 kt are still blowing, with only slight
decreases expected through the afternoon. Overall these
conditions are expected to last through Tuesday, but starting
Tuesday night many areas will start to see increasing winds and
seas as a strong front moves in from the gulf. The northern inner
channels will see it first starting as early as Tuesday night. The
southern inner channels will wait until Wednesday morning. S to
SE winds of 20 to 25 kt will be common into Wednesday night for
many areas, but the southern panhandle and ocean entrances will
see the higher winds. Seas, mainly wind driven, will be up to 5 ft
during this time. Winds and seas gradually decrease Thursday into
Friday.
Gulf Waters: A weak front moved through the gulf overnight Monday
and is now pushing into the panhandle this morning. This is has
resulted in diminished winds and switch to a westerly direction in
the post frontal environment. Otherwise winds are low and seas
are only around 3 to 4 ft most of that in the form of a westerly
swell. Winds will be switching to southerly and increasing through
the day Tuesday as a strong front will be moving into the eastern
gulf. Gale force winds will start to show up near Cape Suckling
as early as Tuesday evening and could peak as high as 45 kt
Tuesday night. Gale force winds up to 40 kt will also spread over
the rest of the near shore waters down to Cape Decision through
Tuesday night before diminishing during the day Wednesday. Seas
likewise will be on the rise with seas of 12 to 15 ft likely by
Wednesday for many areas of the gulf mainly from the higher winds
initially. The seas will show a gradual diminishing trend into the
late week, but will still be on the order of 10 to 12 ft due to a
SW swell of 7 to 9 ft (with a period of 14 sec) lasting through
Thursday at least.
&&
.HYDROLOGY...No changes made to the precipitation forecast for the
mid week system, looking at around 2 to 4 inches of rainfall
expected for most areas of the panhandle from Early Wednesday
through Thursday night from an atmospheric river that is aimed at
the panhandle. Highest rainfall amounts look to be focused on the
outer coast from Baranof island northwestward. The timing of the
precip has the northern panhandle getting the rainfall first
followed by the southern panhandle about 12 hours or so later.
Most areas should see the rainfall stick around for around 18 to
24 hours or less. Area rivers and stream are expected to respond
with rising water levels and increased flow starting Wednesday
with high levels lasting possibly into late week for the slower
responding rivers.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning for PKZ644-651-652-663-664-671-672.
     Small Craft Advisory for PKZ642-643-661-662.
&&
$$
SHORT TERM...STJ
LONG TERM...ZTK
AVIATION...GJS
MARINE...STJ
HYDROLOGY...STJ
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