866
FXAK67 PAJK 011818
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1018 AM AKDT Thu Oct 1 2026

.UPDATE...update for the second release from Suicide Basin and
the Flood Warning for Mendenhall River.

&&

.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 night/ An upper level trough is
currently moving through the northern panhandle this morning. It
is bringing stronger and more frequent rain showers and some
higher winds for the northern panhandle. Rain showers have mostly
been confined to the area north of Sumner Strait this morning with
the strongest showers producing occasional lightning along the
outer coast from Cross Sound to Yakutat overnight. Meanwhile the
winds have increased to 25 to 30 kt in N Lynn while other northern
inner channels areas are around 15 to 20 kt.

Highest winds and most frequent showers are expected for this
morning as the upper trough that is powering everything moves E
into Canada. Thunderstorm activity likewise will diminish this
morning along the NE outer coast. Ridging is expected to push into
the southern panhandle Thu night drying things out there, however
rain showers are expected to continue in the northern panhandle
due to SW onshore flow continuing into Friday and Friday night.

Winds will also see a diminishing trend with most areas below 15
kt by Thursday night. Though not before Skagway could possibly
see gusts to 40 mph this morning. A wind advisory remains up for
that area through 1 pm this afternoon. The main exception to the
diminishing trend will likely be N Lynn where S 20 kt winds could
likely continue blowing into Friday night.

.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...18Z TAFs...Scattered showers continue to affect parts
of the northern and central panhandle, but ceilings and
visibilities are generally VFR with just periodic and brief
reductions to MVFR. The heaviest and most persistent shower
activity will likely continue to be along the northern panhandle
and outer coastline through the day. Mainly VFR to persist this
evening, before MVFR becomes increasingly predominant after
09Z-12Z tonight under persistent onshore flow and a return to
lower ceilings.

&&

.MARINE...
Inner Channels: S winds of 15 to 20 kt for most areas of the
inner channels north of Frederick Sound this morning. N Lynn is
showing the highest winds with 25 to sometimes 30 kt overnight at
Eldred Rock. These winds are expected to diminish through the day
with most areas seeing 15 kt or less by this evening and then
persist at that level through Friday night. N Lynn will be the
exception as they could see 20 kt of wind that persists into
Friday evening. Seas generally around 3 to 5 ft this morning with
the highest seas in N Lynn. These seas will subside as the winds
subside today.

Gulf Waters: Generally W to SW onshore flow around 10 to 15 kt
remains the norm across the gulf this morning. This will not
really be changing until Friday night as a new front approaches
from the SW. The front will switch the wind direction to more of a
SE and start to increase wind speeds as well. Gale force winds
look likely by Saturday afternoon and evening along the near shore
waters. Seas are generally around 5 to 7 ft with most of that
being wind wave and very little swell. Not expecting much change
in seas until Friday night when increasing winds from the
approaching front and building SW swell starts to build seas above
10 ft.

Some isolated thunderstorm activity along the NE gulf near shore
waters from Cross Sound to Yakutat Bay this morning. That is
expected to diminish through the morning and should not be a
concern by later Thursday afternoon.

&&

.Hydrology...A second release from Suicide Basin has started and
levels will continue to drop through the day. Levels on the
Mendenhall have started to rise and will continue to rise as the
release continues. Current river level crest projection is around
10ft on Friday. At 10ft, water levels will inundate Mendenhall
Campground with up to 3 feet of water covering low areas as well
as up to 1.5 feet of water covering Skaters Cabin Road. Portions
of West Glacier Trail will be impassable. Areas along View Dr will
start to flood and cause minor flooding of yards. Closure of
pedestrian pathways beneath Brotherhood Bridge and the trail
system on the west side of Mendenhall River during outburst
events. The water level on the Mendenhall River is expected to
fall back below flood stage by Saturday morning.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Wind Advisory until 1 PM AKDT this afternoon for AKZ318.
MARINE...None.

&&

$$

SHORT TERM...EAL
LONG TERM...BAS
AVIATION...MJB/ZTK
MARINE...EAL
HYDROLOGY...DS

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