842
FXAK67 PAJK 220002
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
402 PM AKDT Sat Sep 21 2024

.SHORT TERM...A low pressure system continues to weaken as it moves
over the panhandle. With this, expect winds and rain to continue to
lighten tonight before another strong low enters the gulf Sunday.
For the rest of today, winds will diminish to fresh breezes along
the inner channels, if not already lightened. Stevens Passage and
Clarance Strait will be the last channels to see decreasing
winds. A short break in rain will begin late tonight into tomorrow
morning as a short lived ridge moves through.

The next impact will be Sunday night into Monday as a low sets up in
the gulf allowing for rain and wind to move back into the panhandle.
Rain will begin Sunday evening along the coast before it quickly
becomes widespread rain across the panhandle. For more information
on precipitation see the hydrology section. The tightening
pressure gradient with this low create gale strength winds along
the gulf coast Sunday evening. These tighter gradients allow for
strong breezes to occur in the inside waters. The low pressure
system then continues to sit in the gulf keeping winds elevated.
These winds do not start to diminish until Monday night when the
gradient finally starts to weaken.

.LONG TERM...Monday a deep low in the western Gulf will bring a
wide swath of southwest winds across the majority of the central
and southern Gulf along with a moderate to strong atmospheric
river. Through Tuesday into Wednesday expect the surface pressure
gradient to weaken, allowing winds to diminish and swell to
decrease. Rain continues. See Marine section for higher detail
info.

Early Thursday, attention turns to a possible gale force low
moving north from the coast of Haida Gwaii, with ensembles
highlighting a low transiting along our coast before making
landfall in the Central Panhandle. If ensemble solutions hold the
course this has the potential to be for our first High Wind Watch
of the season for the far southern Panhandle. Mariners planning on
transiting from and to southeast Alaska along the Inside Passage
should take notice, as Dixon Entrance into Clarence Strait are
under the gun to see near 35 knots of southerly wind, with more
extreme outliers suggesting 50 knots. With the position of the low
expect northerly flow in the northern inner channels and easterly
near-gale force coming out of Cross Sound. Dont anchor on
previous wind forecasts, changes will be made as guidance gets a
better handle on the low depth and location.

Snow levels continue to follow their seasonal normal, dropping
below 5,000ft as we move through the week. No snowfall impacts are
currently anticipated at sea level.

&&

.AVIATION...Conditions this afternoon ranging from below minimums
to better than 3000/5 around the Panhandle. Meanwhile the
northeast gulf coast is clear & 7. Those excellent flying
conditions are forecast to spread south and slightly east such
that Panhandle locations from Chatham Strait/Lynn Canal westward
should see 3000/5 or better tomorrow. Instrument conditions still
expected along the Coast Mountains. Marginal conditions from the
ice field west to Chatham Strait. The break in the weather will
come to a close by Sunday evening as the next front arrives with
lower conditions, heavy rain and more LLWS/turbulence.

&&

.MARINE...There will a short break for the gulf and inner channels
as non-impactful winds occur Saturday afternoon and night before the
next low pressure system enter the gulf Sunday. A tightening
pressure gradient with this low will create gale force winds,
organizing out of the southeast, along the gulf coast and into a few
of the inner channels. Highest winds along the inner channels are
expected in Icy Strait, Cross sound, and Clarence Strait. Winds will
stay elevated from Sunday night through Monday evening before the
pressure gradient weakens. The weakening pressure gradient will
allow winds to decrease to fresh breezes Tuesday.

&&

.HYDROLOGY...Monday into Wednesday will feature a very wet fall
storm along with elevated winds. 24-hour rain totals Monday and
also Tuesday near 2 to 3 inches are expected. Expect the worst
conditions to come in early Monday, featuring 6-hour totals near 1
inch early Monday morning. Heavy rainfall diminishing as we move
into Tuesday. Rain continues but at more reasonable rates through
Wednesday.

Coordination with Environment Canada highlight the uptick in IVT
and duration of the AR near Haida Gwaii, with both ensemble mean
runs highlighting the potential for an extreme (AR-4) event. While
the highest values are likely to miss us, its close enough to
warrant some concern in the far south including Hyder. For now
the forecasted rain totals represent the most likely outcome.

Coordination with the River Forecast center showcases a rise in
small streams and creeks but at this time, all major rivers look
to remain below flood stage.


&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ031-036-641>643-652-661>664-671-672.

&&

$$

SHORT TERM...EAB
LONG TERM....AP
AVIATION...Fritsch

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