Debris Flow in Alaska, September 20, 2025

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1036 AM AKDT Sat Sep 20 2025

.UPDATE...Flood Advisory for the Southern Panhandle has been
extended. Update for 18z TAF Issuance.

&&

.SHORT TERM...The heavy rain impacting the area yesterday has
started to wind down this morning. Some areas of heavier showers
continue to move through the panhandle but accumulations have
noticeable slowed compared to yesterday. Some of the showers
moving through the area today could provide heavy periods of rain
and some gusty winds. There is also a slight change for some
thunderstorms across the area today with some CAPE available and
orographic enhancement providing a potential boost. Best chances
for thunderstorms would be along the outer coast this afternoon
from Cross Sound down to Prince of Wales Island. With the low
moving into the area, winds are expected to increase out of the
south and provide some stronger and gusty winds, especially over
the marine areas. For more information on winds over the water,
see the marine section below.

.LONG TERM.../Sunday through Wednesday/...
Key Messages:
- Brief breaks in rain and wind possible Sunday between systems
- Fast moving gale force system to move northward into the eastern
  gulf Sunday night into Monday
- Heavy rain again for far southern panhandle
- Showers continue across the panhandle through midweek

An active fall pattern will continue through the weekend and into
early next week across southeast AK. The major rain event over the
area will start to wind down going into Sunday. Being in a post
frontal environment, moderate rain showers are still possible but
breaks between showers are more likely through midday.

This reprieve will not last long as a fast moving gale force low
moves into the eastern gulf late Sunday night into early Monday
morning. This system will bring another round of heavy rainfall to
the southern panhandle, with ensemble guidance giving up to a 50%
chance of upwards of 3 inches in 24 hours for Metlakatla and
Ketchikan. For the central outer coast including Sitka, guidance
gives a 60% chance of up to 2.5 inches over 24 hrs. These 24 hour
totals are for Sunday at 4pm through Monday at 4pm. Contingent upon
the speed and track of this feature, the timing of heaviest rainfall
is expected early Monday morning. Light to moderate rain will then
spread over the rest of the panhandle from south to north as the low
moves along the outer coast. There is still some model discrepancy
on whether this feature will slowly deteriorate and jump inland in
the vicinity of Mt Fairweather, or if it will weaken, but stay
offshore and continue to meander NW along the gulf coast. This will
largely depend upon the larger circulation in the mid levels
steering it towards the panhandle in the first place.

If the system moves inland near Mt Fairweather, this would lead to
increased storm totals for the northern panhandle, as well as a
longer duration of increased winds for the inner channels. A more
westerly track lingering in the northern gulf would allow for near
gales to continue along the near coastal waters for a bit longer.
Before the primary deviation point, there is model agreement on
strong gale force winds for the southeast gulf and Dixon Entrance
area as the low approaches, with gusts to storm force possible
for far southern Clarence Strait early Monday morning. Seas in the
southeast gulf will also build to 15 ft with a strong
southwesterly swell as the system moves northward through Monday
afternoon.

On the backside of this early week system, there will be
persistent on shore flow with light to moderate showers across the
panhandle through midweek. Throughout the long term forecast
period, maximum temperatures will remain mild between the mid 50s
in the north ranging to around 60 in the southern panhandle.

&&

.AVIATION.../Update for 18z TAF Issuance/...Aviation weather is
mainly jumping between MVFR and VFR conditions now that a
majority of the main frontal band has pushed over. Overcast CIGs
are attempting to raise to AoA 6000ft, but with lower broken
layers and moderate rain passing through VIS continues to dip to
at least MVFR conditions. Another frontal band is expected to
impact the panhandle, bringing moderate to heavy showers and
strong, gusty winds to communities as it passes over. Areas down
south and parts of the central panhandle will feel the greatest
impacts, though northern panhandle communities will still see
drops in categories once the showers reach them. LLWS is present
at a majority of sites and will be the strongest when the band is
passing through. Conditions will continue to fluctuate through the
period, often improving after the frontal band passes through and
then dropping back down with the next one.

&&

.MARINE...Outside (Gulf and Coastal Waters): Fresh to strong breezes
continue this morning as the low currently spinning in the Western
Gulf is expected to move to the east today. As it moves closer to
the area, winds are expected to shift in response as well as the
potential for seeing some increasing speeds, especially for places
south of Cape Edgecumbe. North of here, winds are expected to
remain similar to where they have been or even decrease somewhat.
While winds might decrease, seas are expected to remain elevated
throughout the day for those areas. Current wave heights from
across the Eastern Gulf continue to show wave heights around 8-10
ft with a southerly swell aspect to them. For areas south of Cape
Edgecumbe, wave heights are expected to increase with the
building winds due to the low moving closer to shore and bring
stronger winds.

Inside (Inner Channels): Conditions across the Inner Channels this
morning remain a tale of two variants. Either light winds or fresh
to strong breezes depend on the location. Places like Clarence
strait as well as Scull Island continue to report fresh to strong
breezes this morning. This will change throughout the day though
as a southerly surge of wind is expected throughout the day
starting in the with winds increasing to fresh to strong breezes.
This surge is also likely to bring strong gusts. Besides the
southerly surge, any strong showers or potential thunderstorms
that move over the area could bring strong, gusty winds.

&&

.HYDROLOGY...The heavy rain impacting the area has started to
shift to the south and east leaving the area with showers and some
initial thunderstorm development. With the heavy rain, rivers and
streams rose yesterday and overnight but are slowly starting to
crest this morning. Some showers and thunderstorms impacting the
area could bring periods of heavy rain to the area today and
might cause small, flashy creeks and streams to rise quickly so
attention will need to be paid to those. But the overall threat
for potential flooding is expected to level off or start
decreasing depending on your location in the panhandle.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood Watch until 10 PM AKDT this evening for AKZ326-328>332.
MARINE...Small Craft Advisory for PKZ022-036-053-641>644-651-652-661>664-
     671-672.

&&

SHORT TERM...SF
LONG TERM...STJ
AVIATION...ZTK
MARINE...SF
HYDROLOGY...SF

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