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FXAK67 PAJK 220056

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
356 PM AKST Sat Jan 21 2017

.SHORT TERM...Taku wind event in downtown Juneau persisted to mid
day today...longer than expected. Highest gusts were extremely
localized near the barge dock just south of downtown JNU. Mountain
wave conditions are collapsing this afternoon and I expect these
downtown winds to die off rather quickly rest of afternoon.

Elsewhere Gale to Storm Force winds in Lynn Canal will persist
into the evening due to favorable N-S pressure gradients. The cold
high pressure in Yukon expected to shift slowly east through Sun.
This will help reorient the pressure gradients from N-S to more
E-W and is reason for diminishing winds and freezing spray in
northern inner channels later tonight and Sun. Made only very
minor adjustments to min temps Sat night. While less wind expected
so is greater cloud cover to mitigate over cooling tonight.

Clouds are associated with complex upper trough pattern over the
NE Pacific. Several weather fronts will begin affecting SEAK
starting Sun. One frontal band is moving north along BC coast
today and will spread clouds over southern Panhandle tonight.
Chance of precipitation is low at first and mainly over the
southern and SW part of Panhandle. This feature will continue
N-NW Sun and begin to merge with another frontal system
approaching from the west on Sun. Together these features will
increase likelihood of snow and rain along the central and
northern coast later Sun. See long term discussion for how the
pattern will continue to evolve during the week.

.LONG TERM...A weak surface ridge over the western gulf at the
start of the extended range forecast period will shift east as a
very powerful storm south of the Aleutians moves east. This low
will weaken dramatically as it enters the western gulf on Tuesday
and the center of circulation is not expected to progress as far
east as Kodiak. A low will form on the frontal boundary to the
southwest but it too is expected to remain west of the local
forecast area.

The original low and the wave that develops are both forecast to
push strong fronts across the gulf with the first arriving on the
outer coast Tuesday morning and the second sometime on Thursday.
Both are expected to advect warmer low level air into the area
from the west. A third front is forecast to enter the eastern gulf
late in the week or early weekend. This system will also feature
low level warm air advection. All three systems will act to
elevate snow levels, but weather at the beginning of the extended
range will feature accumulating snow for many locations through
mid week.

The Tuesday and Thursday front both feature gale force winds over
the eastern gulf with small craft winds on the inside. Possibility
of gale over Clarence Strait Tuesday night and Thursday night as
well, but the current forecast reflects only small craft winds.

Little change to the forecast other than to revisit temperatures
and snow levels with minor changes there. Increased PoP Sunday
night and Monday with some changes to QPF and snow amounts early
on as well. Overall forecast confidence is average.


.AJK Watches/Warnings/Advisories...
MARINE...Gale Warning for PKZ012.
     Small Craft Advisory for PKZ011-013-021-022-031>036-041>043-051.
     Small Craft Advisory due to Seas for PKZ052.



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