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FXAK67 PAJK 242338
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
338 PM AKDT WED AUG 24 2016

.SHORT TERM...Surface ridge over the eastern half of the gulf it the
main feature of the area for today. The ridge will be generally
stationary however does seem to be drifting westward slightly,
and as a result a northwest winds will increase to 20 - 25 kt
Thursday afternoon.

The ridge position over the eastern gulf is allowing a short wave
to ride across the top side of it to impact the central and
northeast gulf coasts. Rains will continue with rain rates
increasing at Yakutat with perhaps a half inch tonight and an inch
possible Thursday. The rainfall for the northern panhandle looks
to be limited to the north of Frederick Sound with the southern
panhandle staying dry.

The southeast portion of the panhandle (Ketchikan/Metlakatla to
Hyder) on Thursday looks to be on the sunny side again with
temperatures warming back into the lower to upper 70s depending
on the locations and wind directions.

Patchy to areas of fog will develop overnight and will then
dissipate through Thursday morning, with the best chances for fog
to dissipate over the southern sections.

.LONG TERM...Trough riding over the flattening upper level ridge
will cross over the northern panhandle into British Columbia
through Friday then drop southward Saturday. High pressure ridge
axis over the gulf will have moved over the western gulf by Sunday
as another upper level low moves in from northeast then
potentially to the southeast gulf Monday into Tuesday. Large
amount of uncertainty with the developing weather pattern for
Sunday due to interaction of this wave moving in from the Yukon,
the high pressure ridge over the gulf, and a low over the Bering
Sea.

Short wave for Friday will move from the Yakutat area eastward
then to the southeast through Friday. Potential heavy rainfall
still over Yakutat and then the northern and north-central
panhandle (see Hydrology section below.) As upper trough moves
over precip will begin to diminish and with flow shifting to the
northwest then offshore into Saturday. This sets up the weekend
for a warm and dry start. Did a slight speed up to clearing skies
but for now left temps as is. Due to uncertainty with the next
waves moving in have left the mostly cloudy with chance of rain
forecast starting later in the day Sunday and into next week.
Slight increase to forecast gulf winds on lee side of ridge for
Friday then a diminishing trend in the winds Saturday onward.

New models still in line through Saturday with previous forecast
so little change. Overall like the 12z NAM/GFS for any minor changes
to gulf winds or pop. Sunday onward once again seeing large spread
from run to run and between models. Used a blend of ECMWF/GFS/WPC
to try and keep a trend of the low position. Forecast confidence
is above average into the Saturday then drops significantly by
Sunday.

&&

.AVIATION...IFR to MVFR flight conditions for most of the
northern and central TAF sites today has slowly improved to only
impact the northern panhandle this afternoon. Am expecting more
fog for the coastal and inner channels tonight. Therefore am
expecting IFR conditions overnight to early morning for Sumner
Strait northward and including the western Prince of Wales as
well. Yakutat will be impacted more with the lower ceilings with
the continued rains overnight.

&&

.HYDROLOGY...Rainfall of 1 to 2 inches across the northeast gulf
coast through Thursday afternoon and evening. Higher rainfall for
the higher elevations will put a little more rain into the basins
there...however am not expecting any issues with the rivers there.
Rainfall of the Taiya river basin through Thursday night and early
Friday is resulting in forecasts for the Taiya to rise above
action and below minor flood stage Friday evening near a stage of
16.3 feet.

Also we are watching the Mendenhall Lake reading as the levels
are rising at a good rate today, which seemed to be more than
what a normal rainfall runoff may account for. RFC and our office
will keep a eye on the levels in case more develops from this
situation.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-041.
&&

$$

Bezenek/PRB

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