Area Forecast Discussion
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FXAK67 PAJK 201701 CCA

Southeast Alaska Forecast Discussion...CORRECTED
National Weather Service Juneau AK
901 AM AKDT Thu Jul 20 2017

.SYNOPSIS...A high pressure ridge over the panhandle will slowly
weaken through Friday as an upper level low slides across the
southern gulf. The northern part of a frontal band over the
central gulf will shift to the SW while the southern part of it
moves into the southern panhandle on Friday.


.SHORT TERM.../Thursday through Friday night/ Fairly quiet day
across the panhandle as a ridge over the panhandle keeps a weak
front nearly stationary over the central gulf. As a result most of
the rain and wind with the front has stayed well offshore. There
are still some clouds lingering in the panhandle (mainly northern
and central) though they are not as low as they have been the
last two days. Winds have remained low.

Short range period will be a time of transition as the ridge over
the panhandle slowly weakens while an upper low tracks across the
southern gulf. Cloud cover will be a little tricky to pin down as
low level flow gradually turns more and more offshore through
Friday raising the possibility that various areas will see
significant breaks develop. Decided to leave many areas as mostly
cloudy due to lingering low level moisture and no strong waves
incoming to clear it out. This changes into Fri and Fri night as a
front coming in from the south will increase easterly flow across
the northern panhandle resulting in clearing skies.

Speaking of the front, it starts out oriented north to south in
the central gulf but then starts to tilt more east-west by Friday
as the upper low swings across the southern gulf. The southern
part of the front is expected to hit the southern panhandle
starting Fri with rain spreading north through early Sat. Short
range models have sped up the front compared to previous forecasts
by about 3 to 6 hours. Other changes include increased wind for
the southern panhandle Fri into Fri night as the front moves
through. Generally used GFS and Nam for guidance today.

.LONG TERM...Saturday through Thursday as of 10 pm Wednesday/Saturday
begins with a weather front moving northeastward across the
Panhandle. As time progresses preciptiation spreads northward
Saturday with rain in the forecast for most of the Panhandle by
Saturday afternoon. What begins as rain Saturday will transition
into a diminishing shower regime through early Sunday, with a
clearing likely over the central Panhandle late Saturday night
into Sunday morning.

Behind the system an upper level trough and weak surface ridge
build over the eastern gulf and Panhandle through the middle of
the week. Relatively light zonal winds and low chances of
precipitation are associated with this weather pattern.

Most significant changes in the long term were made to Saturday`s
forecast shifting the low pressure center further northeast in
the Gulf. The NAM was used as primary guidance for Saturday and
mainly WPC was used to handle Sunday and beyond.


.AJK Watches/Warnings/Advisories...
MARINE...Small Craft Advisory for PKZ041-052.




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