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FXAK67 PAJK 221255
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
455 AM AKDT Sun Sep 22 2024

.SHORT TERM.../through Sunday night/...
Quick Notes:
-A short-lived break in the rainy weather today.
-Light winds will be found are the area as well.
-Front later today brings back the heavy rain and stronger winds
 tonight.

Details:
A short break in rain is in the forecast for SE AK today.
Current satellite loop shows clouds trying to thin out so if that
trend is able to continue, parts of the area may end up with a
sunny Sunday.

The next round of heavy rain moves in tonight as a low sets up in
the western 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 across the panhandle. For more
information on precipitation see the hydrology section.

The tightening pressure gradient with this low will create gale
force winds along the gulf coast Sunday evening. These tighter
gradients will also allow for strong breezes to occur in the inside
waters. The low pressure system will stay in the gulf, keeping winds
elevated. These winds do not start to really diminish until Monday
night, when the gradient 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...
Departing system has left IFR to VFR flight conditions across the
panhandle this morning. Anticipating gradual improvement through
early afternoon to predominate VFR conditions with CIGS AoB 5000
to 7000ft for much of the area. VFR conditions on Sunday will be
short- lived as another system moves into the Gulf of Alaska with
rain chances and LLWS increasing from west to east after 00-06z as
front pushes inland. Sustained winds should remain less than
15kts through mid afternoon, increasing through tonight up to
20kts with isolated gusts up to 30kts with strongest winds along
coastal and southern panhandle TAF sites. Likeliest locations for
mechanical turbulence and LLWS across Gulf coast and interior
southern panhandle by Sunday evening into Monday morning.

&&

.MARINE...
A tightening pressure gradient with the next 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...Gale Warning for PKZ036-644-651-652-661>664-671-672.
     Small Craft Advisory for PKZ011-013-021-022-031>035-053-641>643.

&&

$$

SHORT TERM...GJS/EAB
LONG TERM....AP
AVIATION...NM

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