548
FXAK67 PAJK 010809 CCA
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1020 PM AKDT Wed Sep 30 2026

.SYNOPSIS...

Key Messages:

- Onshore flow bring rain showers tonight into Thursday. Gusty
  winds and moderate showers possible for northern panhandle.

- High pressure will bring a bit of clearing and drier weather for
  southern panhandle by Thursday and central panhandle by Friday.
  Northern panhandle will remain cloudier with showers.

- A stronger system and weak atmospheric river will bring gusty
  winds, elevated seas and moderate to heavy rainfall for the
  weekend.


&&

.SHORT TERM.../through Friday/...Showers have picked up in
intensity across the gulf coast this afternoon as previously
forecast with continuing southwesterly onshore flow. An upper
level trough will help to push a surface front into the northern
panhandle and outer coast tonight into Thursday. Cooler air aloft
pulled in behind the front combined with the lift from the
elevated trough will lead to decent instability for thunderstorm
potential along the northern gulf coast, spreading down to around
Cape Spencer. By Thursday afternoon the thunderstorms are expected
to diminish, though rain showers will continue across the
northeast coast and most of the northern 2/3rds of the panhandle
as the upper level trough pushes inland. This will also lead to
increased surface winds across the inner channels with
particularly windy conditions expected in the usual spot, Skagway.
A wind advisory was issued from 7am to 1pm Thursday when the
strongest winds are expected with gusts up to around 40 mph.

Onshore flow will continue into Friday across the panhandle,
though with some variation in weather from Thursday. Rain shower
coverage is expected to primarily continue north of Frederick
Sound in the inner channels and northwest of Cape Decision on the
outer coast. This change is due to a weak ridge of high pressure
building in over southern BC and pushing up into the southern
panhandle briefly Friday. This should limit shower development and
weaken onshore flow for the period, as well as clear out some of
the cloud cover. However, with the timing of clearing, some fog
development cannot be ruled out for the southern panhandle for
Friday morning. A more potent pair of systems is expected to bring
moderate to heavy rain to the majority of the panhandle this
coming weekend. For more information, see the long term discussion
and stay tuned for future forecast updates.

.LONG TERM.../Saturday through Tuesday/...A low pressure system
will enter the Gulf of Alaska this weekend, bringing gale-force
winds to the outer coast along with periods of moderate to heavy
rainfall associated with a weak atmospheric river. The initial
wave of rain begins late Friday night into early Saturday morning
as a front reaches the panhandle, impacting mainly the northern
region and more so the NE Gulf coast. A stronger wave then
follows, arriving by early Sunday morning. As the low slowly
dissipates near south-central AK, it will meander and track
multiple fronts across the panhandle. This setup, reinforced by a
consistent slew of upper level troughs and divergent flow aloft,
keeps precipitation in the forecast for the extended period,
although overall impacts are expected to diminish gradually
heading into next week. One thing of note is as the low
dissipates, the pressure gradient over the northern panhandle
becomes more north to south oriented, causing a potential increase
in winds within Lynn Canal through Monday and Tuesday.

Impacts associated with this weekend system will initially start
along the NE Gulf coast and as far south as Baranof Island, also
upwind of higher elevations. From Sunday through Monday, heavier
precipitation will push south across most areas, particularly
targeting the Misty Fjords region. The highest confidence for 24-
hour rainfall accumulations during Sunday`s stronger wave ranges
between 1.5 to 2.5 inches, with localized amounts reaching 4 to 5
inches over higher terrain. However, at this time there is a low
(25%) chance that lower elevation areas surrounding Icy Strait, such
as Juneau and Gustavus, could exceed 2.5 inches. A significant
southerly jet will move along the coast Saturday, shifting
southwesterly by Sunday morning and likely bringing 35 to 40 knot
sustained winds from Cape Spencer north to Cape Suckling. Overnight
Saturday into Sunday presents the greatest concern for elevated and
gusty winds over the southern panhandle and inner channels, then
trending on the decline Monday morning.

&&

.AVIATION.../through Thursday evening / After 06z TAF package
Issuance.

Scattered to isolated showers moving into the panhandle from the
eastern part of the gulf, while a slightly more organized feature is
moving through the NE Gulf Coast. As the front moves through and the
pressure gradient tightens, a period of gusty winds is expected for
late Wednesday night and early Thursday. Mainly VFR conditions with
localized marginal ceilings. As the shower activity picks up,
heavier showers may reduce flight visibilities tonight and early
Thursday.

&&

.MARINE...
Outside:
For Wednesday, a low continues to persist along our coast, driving
onshore flow and continued showers. Winds are at moderate breezes
along the coast, with dominant seas out of the WSW focused 5 to 7
ft near 9 seconds. Underneath is the usual southerly swell from
the south Pacific with some energy focused near 15 to 18 seconds
from tropical activity in the central and eastern Pacific.

Wednesday night, expect westerly winds to build in in the central
Gulf to fresh breezes, helping increase WSW seas a bit, perhaps 7
to 8 ft near 9 seconds. Winds and seas begin diminishing again
Thursday morning into Friday. Through Friday a gale force low will
slide along the Aleutian Storm Track, with winds becoming
southerly in the eastern Gulf. Anticipate easterly gales to build
along Cape St. Elias by Saturday morning. From Cross sound south
to Dixon, southeasterly winds build to near gale force to strong
breezes. Large and confused seas near 11 to 14 ft impacting much
of our coast Saturday into late Sunday.

Inside:
Simply put, Friday will likely be the best low wind day across
the inside. The exception, per usual, is northern Lynn Canal where
we will likely hold on to fresh breezes into Friday.

For Wednesday, a low-pressure system along the northern coast
will keep the northwest-southeast pressure gradient over the
region, driving southerly flow through the inner channels and
easterly flow out of Icy Strait/Cross Sound. Overall, winds
strengthen through Wednesday night, driving fresh to strong
breezes over much of the central and northern inner channels.
Dominant feel of Lynn Canal will be strong breezes, with a few
hours of near-gale force conditions tonight. Thursday afternoon,
winds start to diminish over the region as high-pressure forms
over the area, bringing a break from higher winds into Friday
night. By the weekend a gale force low will position itself in the
Gulf, freshening up southerly winds across the inside once again;
strong breezes to near-gale force likely with areas of gale
force.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Wind Advisory from 7 AM to 1 PM AKDT Thursday for AKZ318.
MARINE...Small Craft Advisory for PKZ012-013.

&&

$$

SHORT TERM...STJ
LONG TERM...BAS
AVIATION...Bezenek
MARINE...AP

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