NWS Juneau, AK wrote its last area forecast discussion before the first event at Sep 16, 9:36 PM AKST, 5 hours 24 minutes earlier.
Area forecast discussion, Sep 16, 9:36 PM AKST, 5 hours 24 minutes before
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1036 PM AKDT Tue Sep 16 2025
.UPDATE...
Update to the aviation section to include the 06z TAF issuance.
&&
.SHORT TERM...
Key Points:
- A storm force low continues to move north into the southern Gulf
of Alaska.
- Areas near the eastern gulf coast will see winds increase up to
50 kts.
- Land winds along the gulf coast are expected to see wind gusts
up to 60 mph.
Details: A strong low continues to make its way toward the gulf this
afternoon. From this low, we have seen increased gale force winds up
to 40 kts west of Haida Gwaii. As this low moves north to just west
of the panhandle, winds will increase to high gales of 35 to 45 kts
and storm force winds up to 50 kts. The strongest of these winds are
expected west of Baranof Island late tonight into early Wednesday
morning. For land areas, the strongest winds are expected along the
outer gulf coast. As the low moves north, so will the area of
strongest winds. Starting this evening, areas on Prince of Wales
Island and Annette Island will have times of wind gusts as high as
60 mph. As this low moves north, these stronger winds will reach
Baranof Island, Western Chichagof Island, and near Mount
Fairweather. Even though the strongest winds are expected in those
areas, other land areas can see wind gusts up to 45 mph this evening
into tomorrow morning. These strongest winds will begin to diminish
Wednesday afternoon and evening. Areas around Skagway will be the to
see the winds diminish.
Winds will be the main impact from this low, but times of moderate
to heavy precipitation will occur as this low sends a front across
the panhandle. The heaviest of this rain will fall along the central
and northern panhandle. The highest rain totals will be near Yakutat
as the low continues to move north eventually weakening and moving
inland. We will continue to closely monitor this low as it moves
north along the panhandle bringing strong winds and heavy rain.
.LONG TERM.../Thursday through Sunday/ Through the rest of the week
and into the weekend, systems will continue to bring rain across the
panhandle with little to no breaks between systems. The
precipitation amounts are looking to be impactful due to the longer
duration of moderate to heavy rainfall. EFIs are showing an
increasing trend of confidence of extreme precipitation as the
systems move through, along with a shift of tails of 0 over the
northern panhandle 00Z Friday through 00Z Saturday and over the
southern panhandle 00Z Saturday through 00Z Sunday.
This is also something to keep an eye on moving forward due to
indications of it being a potential AR event from Thursday through
Sunday. GEFS and EC AR guidance shows potential for a moderate AR
event that will be long duration with a lower peak in IVT. Models
still are showing a bit of spread in the precipitation amounts
across the panhandle, and are not fully aligned on where the
higher IVT values will impact, with the GEFS bringing it more
southward to the coast of British Columbia while the EC has it
approaching closer to the southern panhandle.
Overall expecting 2 to 3 inches across the northern Gulf coast in
24 hours Thursday, and around 1 inch for the rest of the
panhandle. As it moves to impact the rest of the panhandle, Friday
into Saturday, the 24 hour totals for the central and southern
panhandle will be between 2 and 3 inches as well. The highest
rates are expected to be Friday into Saturday afternoon, with
areas in the central panhandle (Juneau, Sitka, and Petersburg)
having a 40 to 50% chance of exceeding 3 inches by midday Saturday
when using the NBM 5.0 and 4.3 probabilities. The southern
panhandle, particularly around Ketchikan, may be somewhere to
watch closely as guidance begins to narrow down on precipitation
values for this time frame, as NBM probabilities show a 60% chance
of exceeding 3 inches in 24 hours, a 30 to 40% chance of
exceeding 4 inches, and a 15% chance of exceeding 5 inches in 24
hours. The most 24 hour accumulation Friday afternoon through
Saturday afternoon is expected to be between 2.5 and 3 inches,
though higher amounts may be expected if the IVT values are
directed more along the southern panhandle on the 20th.
Winds in these upcoming systems are expected to be at most high end
gales, with the majority of the increased winds to be along the
outer Gulf coastline, particularly the northern Gulf coast on
Thursday night.
&&
.AVIATION.../through tomorrow evening/...Wind and rain are
roaring back into SE AK Tuesday night into Wednesday. A
storm force low is racing north through the eastern Gulf of
Alaska. As of 1030PM, observations near the low have indicated
wind speeds in excess of 50 kt sustained near surface levels, with
gusts in excess of 80 kt at elevation in parts of the southern
panhandle already being observed. This low is expected to
continue to develop and strengthen through tonight as it races
north.
As the low moves in overnight, MVFR conditions will begin to move
into the southern panhandle. By 10 to 12z, these MVFR conditions
will arrive in the Icy Strait corridor to the Yakutat area. By 15
to 18z, these MVFR conditions will reach those in the far northern
panhandle. The MVFR conditions would be mostly due to CIGs but
can't rule out some MVFR due to VIS under the heavier rain rates.
The other concern, as previously mentioned is the wind, both at
the surface and LLWS. Surface winds will steadily increase tonight
as the low tracks north. LLWS will impact most of the panhandle
this evening and overnight. LLWS values will be around 40 to 50
kts around 1000 to 2000 feet, though some channeled areas will see
LLWS eclipse this, particularly along the outer coast and for the
Icy Strait Corridor northward. As the low wraps up, the LLWS will
decrease beginning around 16 to 18z in the far southern
panhandle. The decreasing LLWS will move north, reaching the Icy
Strait corridor by 03 to 06z Thursday and by 10 to 12z Thursday in
the far northern panhandle.
&&
.MARINE...
Outside(Gulf and Coastal Waters):
A Storm Force low continues to develop and move into the eastern
Gulf of Alaska. As of Tuesday afternoon we are starting to see
winds build to gale force, with 40 to 50 knot SE winds impacting
our coast Tuesday night into Wednesday. Seas near 33ft are
expected to build with the highest winds/seas east of the low
center, moving towards the northern coast Wednesday. Wednesday
afternoon SE storm force winds become SW gales, diminishing by
Thursday morning.
Inside (Inner Channels):
Tuesday afternoon winds are currently in their lull, with Pt.
Couverden reaching 30 knots at times. We anticipate winds to
build from south to north over the next 18 hours, with Clarence
Strait reaching near- gale force conditions before midnight
tonight. Gales, to strong gales, move up the inner channels
through early Wednesday morning, persisting through the early
evening. By early Thursday winds will trend down. Seas of 8 to 9
ft are anticipated for Northern Chatham Strait and Lynn Canal. Of
particular concern is the potential for stout southerly seas of 10
to 18 ft impacting the ocean entrances of Sumner Strait and also
near Pt. Gardner at the intersection of Southern Chatham Strait
and Frederick Sound.
&&
.HYDROLOGY...Rain continues across the northern panhandle
this evening, with highest rates between 0.05 and 0.10 inches an
hour. There will be a brief break in the rain this evening for the
central and southern panhandle before the next front moves up from
the south late tonight. This next front will bring the highest
precipitation amounts to the central and northern panhandle, with
between 1 and 2 inches expected in 24 hours to areas north of Sitka,
with higher accumulations possible along the NE Gulf coast and for
higher terrain areas. Yakutat will see between 1.5 and 2.5 inches
total in 24 hours as the low moves into the northeast Gulf by late
tomorrow night. The southern panhandle, however, will only see
between 0.5 and 1 inch in 24 hours from this frontal passage through
tomorrow night. With this rain, no significant flooding is expected
at this time, but rivers and streams will see rises due to the
rainfall.
The rainfall will continue throughout the week and into the weekend,
with the systems moving through Thursday onwards bringing an
expected 2 to 3 inches of rainfall in 24 hours as a potential
moderate AR moves into the panhandle. This largely appears to be a
longer duration, lower intensity event lasting Thursday through
Sunday with some areas seeing chances of getting above 3 inches in
24 hours. The heaviest rates look to be between 0.25 and 0.35 inches
every 3 hours, with potential for higher rainfall amounts due to
orographic forcing.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind from 10 AM AKDT Wednesday through Wednesday
afternoon for AKZ317.
Strong Wind Wednesday afternoon for AKZ318.
Strong Wind from 10 AM AKDT Wednesday through Wednesday
afternoon for AKZ319.
Strong Wind from 7 AM AKDT Wednesday through Wednesday afternoon
for AKZ320.
High Wind Warning until 7 PM AKDT Wednesday for AKZ322-323-327.
Strong Wind from 4 AM AKDT Wednesday through Wednesday afternoon
for AKZ324.
Strong Wind from 7 AM AKDT Wednesday through Wednesday afternoon
for AKZ325.
High Wind Warning until 1 PM AKDT Wednesday for AKZ328-332.
Strong Wind from 4 AM to 7 AM AKDT Wednesday for AKZ329.
Strong Wind until 4 AM AKDT Wednesday for AKZ330.
MARINE...Storm Warning for PKZ642>644-662>664-671.
Gale Warning for PKZ011>013-021-022-031>034-641-651-661.
Small Craft Advisory for PKZ035-036-053-652-672.
&&
SHORT TERM...EAB
LONG TERM...Contino
AVIATION...GFS
MARINE...AP
HYDROLOGY...Contino
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