166
FXAK67 PAJK 051823 AAA
AFDAJK

Southeast Alaska Forecast Discussion...UPDATED
National Weather Service Juneau AK
1023 AM AKDT Sat Jul 5 2025

.UPDATE...For aviation and marine late morning updates.

&&

.AVIATION UPDATE...Not a lot of change in the near term for the
next 6 hours except for gradually lifting the fog around Skagway,
then refining the mention of some scattered showers around
Gustavus, Petersburg, Wrangell, and Klawock this afternoon.
Probabilities of lower VSBYS and CIGS to MVFR and possibly
periodically to IFR increase late tonight into morning from west
to east as the next occluded front moves in from the GULFAK.
/Garmon

&&

.MARINE UPDATE...Updated to increase winds at Cross Sound and Cape
Spencer area to 15 kt out of the east as we are seeing a bit of a
reverse thermal gradient creating essentially a land breeze
through early afternoon, which is still expected to reverse to a
SW wind 15 kt later this afternoon. Other areas looked on track
with just some minor adjustments for winds in Clarence Strait
where the weak trough moving in across Dixon Entrance is enhancing
the pressure gradient there.  /Garmon

&&

.PREV DISCUSSION...ISSUED AT 504 AM AKDT Sat Jul 5 2025...

SHORT TERM...Little to no winds across the inner channels has
kept an overcast mid-level cloud deck over most of the norther and
central panhandle looking at satellite. Most models also have the
clouds pushing northward with a distinct break between the
northern clouds and a trough across the south. This idea is
starting to show up on satellite, but clouds across the north are
much more widespread than models have, so backed off on the
improving trend to be more in line with current conditions.
Remnant clouds from thunderstorms over the Yukon on Friday tracked
southward over Haines/Skagway late last night, causing some light
showers, extending to Yakutat briefly. Most models have these
showers fizzling out, but a few sprinkles seem probably enough
through the early morning hours up north and into the afternoon
elsewhere.

Further south, a trough of low pressure will very slowly track
across Dixon Entrance through Saturday. This will cause winds to
increase in that area through the day. This will also cause some
showers across the southern areas, becoming more numerous late
Saturday night as another front catches up and merges with the
first, pushing the whole front northward into the central
panhandle by Sunday morning.

Temps were not adjusted with this forecast package, however any
chance for highs getting into the upper 60s will be highly
dependent on sunny breaks. Due to lower confidence in the sky
cover forecast, there is also lower confidence in the temperature
forecast.

LONG TERM.../As of 353pm Friday/ Key messages:
- Temperatures remain seasonable heading into next week.
- Front to bring widespread rain to the panhandle Sunday.
- The next low pressure system enters the gulf at the start of next
  week.
- Heavy rain still on track for far southern panhandle Monday
  into Tuesday.

Details: Toward the end of the weekend, a low will slide into the
northwest gulf and a trough extending from it will bring a shift
to more southerly flow over the panhandle and increasing
precipitation rates. The heaviest precipitation currently looks to
be more focused on the northern panhandle than the central and
southern areas for Sunday. Another system will move into the
southern gulf early next week bringing widespread moderate rain,
with heavy rain on tap for the far southern panhandle along with
increased marine winds. For more information see the marine
discussion.

Model discrepancies still exist with the track of this early week
system, however overall the trend has winds increasing along the
eastern gulf to fresh to strong breezes by Tuesday along with a
fresh influx of rain for the southern panhandle, spreading
northwards Tuesday. Ensemble trends continue to show a signal for
heavy rain with this early week system impacting the far southern
panhandle. The ECMWF Extreme Forecast Index still has SoT values
near 2 for QPF for the far southeastern panhandle of more than 80%
members, for the 24 hr period from Monday afternoon through
Tuesday afternoon. The track of the plume of moisture responsible
for producing this heavy rain and the surface low that is guiding
it will be the primary forecast challenge heading into the next
work week. While continued model uncertainty is still providing a
spread range of potential impacts for this system, forecaster
confidence continues to grow for heavy rainfall for the southern
panhandle. Stay tuned for further developments through the holiday
weekend.

AVIATION...VFR conditions will continue to remain predominant
across most locations through the day on Saturday, with some fog
and low lying stratus which formed during the overnight hours in
a few spots quickly dissipating through the morning hours. Chances
of rain will increase, along with more windy conditions as a
system moves up from the S Saturday night into Sunday. By Sunday,
anticipate many locations will be back to MVFR, with ceilings for
some places falling below 3,000 ft.

MARINE...Inside Waters: Light and variable winds to start
Saturday morning will become largely S 10 kt in the afternoon.
Exception to this will be Clarence Strait that will see a
tightening pressure gradient as a trough slowly crosses Dixon
Entrance, have increased expected SE winds for this area to 20kt
in the afternoon as a result. The increasing trend will spread
northward late tonight with 15-20kt winds most places on Sunday as
a more organized front moves through.

Outside Waters: A trough over the southern SE gulf will cause
SE-E winds to increase to 20kt today with some higher gusts
through Dixon Entrance. Tonight, a low center will track northward
across the western gulf with a front passing over the eastern gulf
through the day Sunday. Have increased winds with this front to
20-25kt, and a barrier jet along the north-central gulf coast of
25-30kt late Saturday night through Sunday afternoon. Seas at the
gulf buoys are reporting 3-5ft, with a S-SW swell of around 9
seconds. Not expecting a big increase in seas with the Sunday
front, building 6-8ft with the barrier jet/small craft area.

HYDROLOGY.../As of 353pm Friday/ Main story for hydro is heavy
rain potential for the far southern panhandle Monday into Tuesday.
A front moving into the panhandle on Sunday could serve as a
primer for streams down there, however the forecasted location of
the parent low means the heaviest rainfall Sunday will be limited
to the northern and central panhandle.

For Monday and Tuesday, the track of the surface low is key to the
amount of time the heaviest banding of rainfall and overall
moisture plume will be aimed at the southern panhandle. A more
impactful model solution would see 24 hr rainfall totals for
Metlakatla and Ketchikan reaching upwards of 2.5 inches, with
heaviest rain rates projected for Monday night into Tuesday
morning as of this discussion. A less impactful solution would see
rainfall totals near 1 inch over the warned area, due to the
system being much more progressive, limiting the period for heavy
rainfall over the area. Either way, periods of heavy rainfall are
expected with this system early next week with river and stream
rises to bankfull are possible, though no flooding is expected at
this time. Stay tuned for updates as we go through the holiday
weekend.

&&

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

&&

$$

SHORT TERM...Ferrin
LONG TERM....STJ
AVIATION...GFS
MARINE...Ferrin
HYDROLOGY...STJ


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