Gale Warning 180, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
249 PM AKDT Tue Aug 29 2017

.SHORT TERM.../Through Thursday/ Rather nice day for most of the
panhandle today with mostly to partly cloudy skies and warmer
temperatures. Wide spread 60s and low 70s for the southern half
while the northern half has had some areas struggling to warm up
due to lingering clouds. The exception to the nice weather is the
northern gulf coast that has been seeing rain all night.

The main forecasting concerns in the next 48 hours are the cold
front moving across the panhandle late tonight and the following
trough for Wed night into Thu. Little if any change made for the
initial front tonight. Still expecting some breezy conditions and
some periods of heavy rain as the front moves through. Heaviest
rain still expected in the northwestern part of the panhandle.

Shower activity continues behind the front and will become more
organized Wed night into Thu as a new trough rotates through the
panhandle. Some of this rain may become heavy at times with a weak
moisture plume accompanying this trough. A mention of slight
chance of thunderstorms was also added for much of the gulf due
to the increased dynamics brought by the trough and a moderately
unstable atmosphere. This feature will also bring some winds to
the area as well. Nudged a lot of the wind speeds in the inner
channels up with the Namnest during this time period resulting in
many areas with 10 to 20 kt winds over land while some marine
areas ended up with 25 kt small craft winds at max. Favored
GFS/Nam for guidance for this system.

.LONG TERM.../ Thursday night to Tuesday / As of 9 pm Monday, a
large broad upper level trough extends south from the mainland
portion of the state into the central Pacific Ocean between 160W
and 170W on Thursday. A broad flat ridge along the west coast of
North America into southern British Columbia will persist into the
weekend, although the axis is moving east inland the Lower 48.

There looks to be several smaller impulses in the trough that
will be climbing out of the trough and into Southeast Alaska to
the weekend, though the timing of the smaller features will be
difficult. Friday into Saturday a larger impulse with its own
closed feature is expected to move east and south across the
Kamchatka Peninsula into the Bering Sea then over the Aleutians by
Saturday.

The overall wet pattern from shower activity looks to continue through
the end of the week. Models are suggesting a ridge building
during the weekend that is trying to hint at break in the rains,
whether it is under day or a slightly longer one. The operational
solutions from the afternoon model runs, are thinking the break
could last longer. However, stayed with the ensemble means from
earlier which has not adopted that yet. Forecast confidence is
above average in the active pattern for the latter half of the
week, however, it's low in timing any individual impulse.

&&

.HYDROLOGY...Periods of heavy rainfall are expected between
Tuesday night and Wednesday across the Panhandle associated with a
cold frontal passage. Rainfall totals between 0.75 and 2.0 inches
are expected across the Panhandle with the highest amounts in the
north. Enhanced rainfall totals are expected along the northeast
gulf coast where an additional 2 to 3 inches of rainfall are
expected between through tomorrow. Another period of wet weather
is expected Wed night into Thu as a wet trough moves through.
Another 0.75 to 2 inches possible in some areas from this
feature through Thu evening.

Wet soils and high rivers associated with the recent wet period
mean that rivers, stream, and creeks are expected to rise during
these periods of heavy rain. No flooding is expected at this time.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Gale Warning for PKZ051-052.
     Small Craft Advisory for PKZ012-022-036-041>043.
     Small Craft Advisory due to Seas for PKZ053.

&&

EAL/Bezenek

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