Flood in Alaska, August 17, 2022

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1050 AM AKDT Wed Aug 17 2022

.UPDATE...Rapid rises on the Taiya River with additional rainfall
of 3/4 to 1 1/4 inches of rain in the area prompted a watch
upgrade along the Taiya River to a Flood Warning. Crest time this
evening is anticipated above moderate flood stage of 17.0 feet.
The warning will be updated, when firmer details from the River
Forecast Center arrives.

&&

.SHORT TERM...Satellite imagery this morning shows our atmospheric
river pushing through the panhandle. An associated warm front is
lifting through the area and temperatures have responded, rising
into the low to mid 60s as early as 4 AM. Observations are
indicating a slight lull in precipitation this morning as rainfall
rates have deceased. This being said, a resurgence in moderate to
heavy rain is expected across the northern and central panhandle
this afternoon. Looking at the next 24 hrs, an additional 1-2
inches is possible with the second wave of heavier rain today.

Expect breezy conditions today as the front pushes through the
inner channels. Winds will begin to diminish late this afternoon
and into the evening. Along with the winds, widespread rain will
shift to scattered showers over the panhandle. By late tonight,
weak ridging begins to build over the panhandle. Some breaks in
sky cover are possible. This combined with winds becoming light
late tonight, the potential for fog will need to be monitored.

.LONG TERM.../Thursday through Sunday/...Today’s long term
forecast update was a big update. Much higher agreement (which
increases confidence) between the deterministic and ensemble
models allowed for big changes and some decisions to be made,
especially on Friday and into the weekend.

Building surface ridge on Thursday will decrease chances for
light rain through the day. This ridge should also keep winds on
the lighter side for both land and marine areas. Daily high
temperatures should also increase, with folks south of Frederick
Sound reaching the upper 60s to 70s on Thursday while folks north
of Frederick South, and along the coast, will reach the upper 50s
to mid 60s.

Friday and the weekend, there is decent agreement among the
deterministic and ensemble models that the panhandle will have a
500mb ridge and surface ridge over the panhandle. And if the peak
of the ridge is offshore, as is currently in the forecast, then
clouds should be on the decrease through the weekend. Partly
cloudy to mostly clear skies are possible this weekend with the
NBM, GFS, and EURO all indicating this pattern.

And with the clear skies comes much warmer temps. Friday’s highs
are in the mid 60s to upper 70s, warmest in the south, and this
continues into the weekend. Less cloud cover will mean these temps
will need to be warmed even more. And with the ridge, winds
should remain on the lighter side through the weekend, until the
next front arrives Sunday into Monday.

Overall, a pleasant weekend is looking more and more plausible as
we get closer.

&&

.AVIATION...Low clouds and patchy fog early Tuesday morning began
to break up as prefrontal showers passed as mixing increased. An
approaching front is causing increasing SE winds with LLWS
beginning between 00-06z, primarily for locations to prone to
surface winds out of the E-NE. Moderate to heavy rain will spread
inland through the evening as well with conditions falling to
widespread MVFR and periodic IFR. Those lower conditions and heavy
rainfall rates will continue Wednesday for Sitka northward. Heavy
rain will diminish through Wednesday evening with conditions
improving to VFR. Watching for fog development and possible marine
layer forming later in the week.

&&

.HYDROLOGY...Recent and ongoing systems have helped to keep SE
Alaskan soils saturated. A quick moving but moist atmospheric
river moving across the northern inner channels will persist into
Wednesday evening. Forecast rain amounts range from 2 to 3 inches
with locally higher amounts possible. The heaviest precipitation
will be from Tuesday night through Wednesday afternoon before the
system slides to the southeast Wednesday evening. A flood watch
has remains in effect for the Taiya River near Skagway for
possible minor flooding by Wednesday morning. A special weather
statement has also been issued for the rest of the northern and
central inner channels due to large river rises but at this time
no significant flooding is not anticipated at this time, but the
event will be closely monitored and updated should the situation
warrant.

&&

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until 4 PM AKDT this afternoon for AKZ025.
     Flood Watch until 10 PM AKDT this evening for AKZ019.
     Areal Flood Warning until 10 AM AKDT Thursday for AKZ018.
MARINE...Small Craft Advisory for PKZ012-013-031>036-041>043-051>053.

&&

Short Term Forecaster...Bezenek
Long Term Forecaster....99
Aviation Forecaster...99

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

Special Weather Statement
National Weather Service Juneau AK
1024 AM AKDT Wed Aug 17 2022

AKZ017-019>026-180230-
Cape Fairweather to Cape Suckling Coastal Area-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-Inner Channels from
Kupreanof Island to Etolin Island-
1024 AM AKDT Wed Aug 17 2022

...RIVER LEVELS ON THE RISE...

The atmospheric river moving through the area this morning has
caused rivers to rise from 0.5 to 2 inches of rainfall. Heavy rain
will move back into the area through the late morning and persist
through the afternoon. Additional rain amounts will be from 1 to 2
inches. This will produce more rapid rise on streams and river but
at this time it is expected for them to remain within their banks.
Some daily rainfall records will
be broken. The heavy precipitation will move out of the area
Wednesday late afternoon as the system slides to the southeast.

For Chilkat River at Klukwan:
At 9:00am the stage was 124.41 feet.
Flood Stage is 128.0 feet.
Forecast: A crest around 126.66 feet is expected around 4:00am
Thursday.
...
For Indian River at Sitka:
At 9:45am the stage was 21.56 feet.
Flood Stage is 25.5 feet.
Forecast: A crest around 24.57 feet is expected around 1:00pm
Wednesday.
...
For Montana Creek at Back Loop Bridge:
At 9:00am the stage was 12.25 feet.
Flood Stage is 15.5 feet.
Forecast: A crest around 14.26 feet is expected around 4:00pm
Wednesday.
...
For Mendenhall Lake :
At 9:15am the stage was 6.24 feet.
Flood Stage is 9.0 feet.
Forecast: A crest around 8.38 feet is expected around 10:00pm
Wednesday.
Impacts:
At 7.7 feet: Nugget Falls trail begins to flood near the beginning
of the trail.

aaron.jacobs

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1104 AM AKDT WED AUG 17 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1003 AM     FLOOD            3 NNW SKAGWAY           59.50N 135.35W
08/17/2022                   SKAGWAY            AK   OFFICIAL NWS OBS

            THE TAIYA RIVER WENT OVER MINOR FLOOD STAGE
            OF 16.5FT AND IS CONTINUING TO RISE RAPIDLY.

&&