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FXAK67 PAJK 242256

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
256 PM AKDT Sat Jun 24 2017

.SHORT TERM.../Tonight through Monday/ Todays front moved in
several hours earlier than expected with every corner of SE Alaska
getting a wetting rain. But, this also means that the main part
of the front has already moved out and precip has already
transitioned to showers with breaks already forming this
afternoon. Expect showers to continue tonight and tomorrow with
relatively light and variable winds through the inner channels.
Exception to this tonight will be 20-25kt winds out of Cross Sound
this evening and near the low center over the gulf.

Have included a slight chance of thunder near the low center over
the SE gulf (marine zones 42 and 43) late tonight into early
Sunday. Lately the peak in lightning activity has been nocturnal,
likely due to radiative cloud top cooling vs. SST creating greater
instability. The limiting factor during the day is the opposite,
plus overcast skies not allowing land areas to heat up.

The upper level low slowly moves east across the central
panhandle Sunday night with NWLY flow prevailing behind it for
Monday. Until this happens, showers will remain in the forecast,
namely on the south side of the low where onshore flow dominates.
The surface low looks to weaken going into Sunday evening as it
passes over the southern panhandle. This weakening trend in part
due to the low center tilting northward as you go aloft, thus less
support. On Monday a ridge of high pressure builds over the gulf
and will help to gradually diminish showers through the day.

.LONG TERM...Tuesday through Saturday...As of 900 PM Fri...Period
begins with models in good agreement depicting an upper ridge
over the E gulf early Tue as a surface low moves into central BC.
Expect a few lingering showers possible Tue, but the trend into
Wed will be diminishing PoPs and sky cover. Model solutions
continue to diverge by mid week, mainly with the strength and
timing of the system pushing into the W gulf. Minor perturbations
ejecting out of the parent low are difficult to time this far in
advance and models diverge significantly with timing of these
short waves. Expect dry weather to continue into Wed before
increasing sky cover and precip chances expand from the N gulf
coast early Wed into the panhandle into Thu. Ensembles continue to
support slightly above normal temps mid next week with NAEFS low
level T 1-2 standard dev above normal. Given the inherited
forecast represented this well and model spreads increase in the
extended made minimal changes to forecast before trending toward
WPC guidance.


.AJK Watches/Warnings/Advisories...
MARINE...Small Craft Advisory for PKZ022-043-051-052.
     Small Craft Advisory due to Seas for PKZ041-042.




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