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FXAK67 PAJK 281354
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
554 AM AKDT SAT MAY 28 2016

.SHORT TERM...Weather over the next 24 hours will be influenced
by a broad and nearly stationary upper low centered east of Haida
Gwaii. At the surface a weak trough of low pressure bisects the
panhandle from east to west, roughly along Frederick Sound. This
trough will shift slowly west and weaken through Saturday night.
North of this feature, a continuation of the partly to mostly
cloudy skies and warm temps are expected due to an offshore flow
regime. Along and south of this boundary, onshore flow and lower
cloudiness, along with scattered shower activity will continue.
Kept the thunder chances along and just south of the surface
trough where greater boundary layer heating and surface
convergence should occur. Added a slight chance of thunder for the
Hyder area as a couple of weak shortwaves rotating westward may
allow convection over western BC to drift into this area during
the afternoon.

Shortwave crossing the coast range early this morning along with a
tight offshore gradient causing some gusty conditions near
downtown Juneau. These winds should relax this morning as the
weak wave pull west and the gradient weakens. Added a small craft
for Cross Sound this afternoon as heating over the interior should
enhance sea breeze circulations.

Models were in decent agreement. Minimal changes were made to the
previous forecast. Used hi-res guidance to adjust wind directions
over the inner channels. Forecast confidence is above average.

.LONG TERM...Upper level omega block with the high centered over
the western interior and lows over the Aleutians and western
Canada will break down early on in the extended range forecast
period. The upper high will pinch off as the low over western
Canada moves west. This low will then begin to weaken and an
upper ridge will build in over the panhandle on Monday. Ridging
will be short lived as an upper low will enter the central gulf
from the south on Tuesday and rotate an upper trough north over
the eastern gulf and panhandle.

At the surface, scattered shower activity will continue over
southeast Alaska as the upper low over western Canada moves west
through Monday. By Monday morning, a front will enter the eastern
gulf from the south and reach the southern outer coast Monday
night. Models not in very good agreement on the timing of this
feature, but all are depicting wet weather through at least mid
week. Updates to this portion of the forecast used a truncated gfs22
pop field. Latest ECMWF and GFS model runs are indicating a second
low and associated front moving in from the west late on
Wednesday, and then a third low approaching from the south
Thursday night.

Winds associated with these various lows not looking like they
will get above small craft intensity over the gulf with limited
response over the inner channels, which would be typical for the
late Spring.

No significant low level temperature advection with any of these
lows, but increasing cloud cover will likely result in lower
daytime highs. extended range temps adjusted down to be more in
line with ensemble model plumes, but will need additional
refinement.

Overall forecast confidence is average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ022.
&&

$$

DEL/Fritsch

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