NWS Juneau, AK wrote its last area forecast discussion before the first event at Aug 10, 5:08 AM AKST, 18 minutes earlier.
Area forecast discussion, Aug 10, 5:08 AM AKST, 18 minutes before
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
608 AM AKDT Sun Aug 10 2025
.SHORT TERM...
Downward trend through this afternoon as the surface low has both
weakened into an open wave trough and has begun to push into
British Columbia. Behind the wave, ridging aloft is causing
pressure rises of around 1 mb per hour with predominantly westerly
wind aloft. This westerly wind is key to areas expected to have
the highest chances at rain this morning and afternoon. Looking
for west facing mountains to have the highest rain chances from
orographic lifting processes. However, looking at satellite, a big
swath of dry air is pushing in from the west as well, which will
erode away precipitation chances today. Therefore, highest chances
of precipitation are this morning, with accumulations less than an
inch.
Looking towards tonight, another surge of moisture looks to push
over the panhandle, primarily aimed between Port Alexander and
Elfin Cove to begin with, then sliding south through Monday
morning. For more information, see the Hydrology section.
.LONG TERM...
Key messages:
- Lingering light rain into Tuesday from a quick moving system to
start the week.
- Winds on a downward swing across the inner channels Tuesday/Wednesday.
- Ridge builds in the gulf through midweek with drier conditions
across the panhandle Tuesday and Wednesday.
- Rain to
Details: Continuing from the short term, the path of the fast moving
system on Monday will lead to increased winds in the inner channels
once more before gradually decreasing. Winds in the gulf will
pick up out of the southwest once more reaching up to strong
breeze (23 - 27 knots) before gradually dropping to fresh breeze
(17 - 21 knots) as a ridge builds over the gulf and flow along the
outer coast turns northwesterly.
This surface ridge coupled with an upper level ridge will bring
drier weather for Tuesday and Wednesday across the panhandle, along
with less cloud cover and warmer daytime highs up to around 70,
particularly for the southern panhandle. Model spread reigns
supreme for late next week, but as of this discussion, sometime
Thursday looks like when we can expect rain and cloud cover to
make their presence know again with a potential low forming in
the gulf.
&&
.AVIATION...Another Less than ideal flying weather day is
in store for SE AK, though conditions will at least marginally
improve in the afternoon across many locations. MVFR to IFR
conditions across the panhandle will experience some improvement
through the day in the wake of a system which departs in the
morning, and much of the panhandle will even experience a lull in
the rainfall through the afternoon. LLWS will generally drop off
through Sunday morning as well.
Starting late Sunday morning, winds will pick up and become gusty
for northern Lynn Canal, including PAGY & PAHN as a low moves
northeastward into the southern Yukon territory of Canada. This
will last through the end of the TAF period.
By late Sunday night though, another system will arrive, bringing
with it more moderate to heavy rainfall, as well as deteriorating
VIS and CIGS.
&&
.MARINE...
Outside: Downward trend in westerlies will continue through the
morning hours, sustained by the rising pressures in the wake of
the passing low pressure. As ridging aloft fully builds the
surface pressure, winds will diminish down to 10 knots. A warm
front will begin to push in from the SW tonight, increasing winds
back to a fresh to strong breeze from Sitka south. Fortunately,
the westerly swell which has been present will have subsided, with
wave heights becoming less swell dependent. Therefore, wave
heights will cap at around 9 ft coinciding with the westerly
winds, counter to the 13-14 ft seas currently on the coastline of
Prince of Wales Island.
Inside: Southerly winds continue to inundate the inner channels
from rising pressures. Widespread fresh southerly breezes will
continue through the morning hours before relaxing slightly and
shifting slightly westward. As the surface wave pushes into
Canada this afternoon, a shift in winds is expected in Icy Strait
to 20 knots from the SW. Only expect this to stick around for
around 6 hours as the warm front pushes in from the SW. Then,
stronger wind placement will shift to Chatham Strait, Stephens
Passage, Frederick Sound, and western Sumner Strait back up to 20
knots.
&&
.HYDROLOGY...
Rainfall will continue across the area as multiple systems move
into the panhandle through the weekend. As of Sunday morning,
heaviest rainfall rates are focused around west facing areas. In
particular, Sitka, Juneau, Petersburg, and areas near Wrangell
are the big winners, with 12 hour accumulations between 1.25 -
2.00 inches. Once more, the panhandle is on the downward trend;
however, Sunday night into Monday will see another plume of
moisture associated with a warm front move over the central
panhandle, then slowly shift southward. What is particularly
impressive about this moisture are freezing levels, which look to
exceed 12000 ft from Sitka southward. This combined with incoming
PW of 1.8 in, or about 180% of normal, will lead to heavy rain for
west facing mountains yet again. Fortunately for these areas,
ridging aloft will limit the amount of dynamic lift for areas over
the panhandle, which will limit overall rainfall. Unfortunately,
however, between the saturated air and very warm temperatures,
still looking at rising rivers and heavy rain. 1.5 - 2.25 inches
are expected, with higher amounts in west facing areas such as
Sitka. No changes with flooding -- no flooding is expected at this
time.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-022-053-641>644-651-652-661>664-
671-672.
&&
SHORT TERM...NC
LONG TERM....STJ
AVIATION...GFS
MARINE...NC
HYDROLOGY...NM
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