Flood in Alaska, August 30 to 31, 2022

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
359 PM AKDT Tue Aug 30 2022

.SHORT TERM...Rain showers move through the northern and central
panhandle this afternoon while the rain has moved out of the southern
panhandle. Some showers have been moderate to heavy at times
through the northern inner channels. Past 24 hour rain amounts
show measurements anywhere between 0.50 to 2.50 inches. Showers
will diminish through tonight making way for a break on Wednesday
as weak high pressure builds through the southern gulf. By
Wednesday afternoon, the majority of the panhandle should see
drying conditions. Some could even see some sunshine through
Wednesday.

Winds 15 to 20 kts will continue this evening through the inner
channels before diminishing late tonight. By Wednesday morning,
winds become 10 kts or less. Lighter winds are expected over land
areas as well. By Wednesday night, a gale force front moves
through the gulf. Across northern Lynn Canal, winds will increase
back up to 20 kts early Thursday morning.

.LONG TERM.../Thursday through Sunday Night/...An approaching
weather front looks to pack a bit of Fall punch with Gales
developing in the barrier jet areas just off the northeastern Gulf
Coast and heavy rain starting in Yakutat Wednesday night due to a
long and deep fetch of tropical moisture(Atmospheric River)
directed at the region. Steady rain will gradually overspread the
rest of the Panhandle Thursday(north) into Friday evening(south).
A Special Weather Statement remains in effect for the northern
half of the Panhandle to highlight the potential of 2 - 7" of
rain from this next system and subsequent waves that form along
the front. Highest rainfall amounts will be for the northern
coastal areas including Yakutat. Rain will continue into at least
the first half of the Labor Day weekend for much of the Panhandle.
Stay tuned to the forecast as details on this next system get
better defined. IVT values of up to ~ 1,000 kg/(ms) look to be
aimed at portions of the Panhandle, primarily the Yakutat area and
northern Panhandle into Friday and sliding farther southward
through the period. through the period. Winds up to Gales are
possible through Friday over the eastern Gulf waters as the front
approaches and the pressure gradient tightens over the region. Winds
up to Small Craft are possible over portions of the Inner Channels
through Friday night as the aforementioned front approaches
Temperatures remain benign with values remaining near seasonable
values with a narrow diurnal spread through the period. No
significant CAA or WAA is forecast at 850 mb through the period by
the models.

Forecast confidence is average as operational models remained in
good agreement on the location and strength of the forecast
synoptic features through the period. Additionally, ensemble
spread was relatively narrow for this far out.

&&

.AVIATION...Rain showers are moving through the northern panhandle
this afternoon with occasional moderate rain reducing visibility
and ceilings down to 3 miles and 1500 ft respectively at times.
This is expected to continue into the evening before the showers
move out. Lower ceilings are expected in some areas late tonight
down to 500 to 1500 feet as lower level stratus may develop. VFR
conditions are expected into Wed and Wed evening as most of the
precipitation should have moved out of the area, through some
lower conditions will start to show up at Yakutat as the next
system starts to move in late Wed night. Winds are not much of an
issue except for some 15 to 20 kt winds around Skagway this
afternoon. Those winds should diminish overnight and remain
somewhat low through Wed.

&&

.HYDROLOGY...A front and Atmospheric River will deliver heavy
rain for the NE Gulf Coast and northern Panhandle area Wednesday
night into Friday morning, sliding southeastward into the rest of
the Panhandle into the Labor Day weekend. Several waves look to
ride northward along this front throught he period Preliminary
forecast estimates of 2 - 7" of rain are possible into the
weekend with highest values to the north(especially near Yakutat)
as the Atmospheric River will be aimed directly at the NE Gulf
Coastal and N Panhandle regions into Friday. An SPS is in effect
to highlight the heavy rain potential. Coordination was done today
with the APRFC and at this time, there are no major flooding
concerns. Stay tuned to the forecast for updates.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

SHORT TERM...CC
LONG TERM....JLC
AVIATION...EAL
HYDROLOGY...JLC

Visit us at http://www.weather.gov/Juneau

Special Weather Statement
National Weather Service Juneau AK
1229 PM AKDT Tue Aug 30 2022

AKZ017>025-311800-
Cape Fairweather to Cape Suckling Coastal Area-Taiya Inlet and
Klondike Highway-Haines Borough and Lynn Canal-Glacier Bay-
Eastern Chichagof Island-Salisbury Sound to Cape Fairweather
Coastal Area-Cape Decision to Salisbury Sound Coastal Area-
Eastern Baranof Island and Southern Admiralty Island-Juneau
Borough and Northern Admiralty Island-
1229 PM AKDT Tue Aug 30 2022

...HEAVY RAIN FOR LATE WEEK INTO THE WEEKEND...

A series of atmospheric rivers will move across the northern half of
Southeast Alaska starting early Thursday near Yakutat, and then
sliding over the northern inner channels on Friday. The heavier rain
is then expected to last through the weekend. From early Thursday to
late Saturday night around 2 to 7 inches of rainfall is expected
overall. The highest amounts are expected over the northeast gulf
coast including Yakutat. The northern inner channels will be in the
middle to lower end of that range with lower values the farther SE
you go. Some uncertainties on total rainfall as terrain could cause
some local areas to get more or less rainfall.

Local rivers and streams are expected to rise as a result of this
rainfall. At this time, flood potential is low, but rivers may reach
or get near bankfull conditions. People who recreate along rivers
and streams across the northern panhandle should remain alert. For
any updated information on this evolving event visit
weather.gov/juneau.

edward.liske