Gale Warning 217, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
244 PM AKDT Fri Oct 20 2017

.SYNOPSIS...A high pressure ridge briefly built over the
Panhandle today. A strong front will move northward tonight and
move into the southeast gulf by Saturday morning.

&&

.SHORT TERM...A low pressure system and associated front will
move into the gulf tonight. Winds will increase tonight and
Saturday as the low pressure system moves into the eastern gulf
and the front approaches the panhandle. A storm warning will be in
effect for marine zone 41 Saturday. Gale warnings will be in
effect for marine zone 43 on Saturday and marine zone 42 late
tonight through Saturday and marine zone 310 tonight through
Saturday. A gale warning will also be in effect Saturday for
Sumner Strait and Clarence Strait. The approaching front will
increase rain showers across the panhandle tonight and Saturday.
Snow will occur near white pass with snow levels there near 1100
feet. Rain showers will continue at times across most of the
panhandle through most of this next week. Temperatures will
continue cool through this next week. The NAM, GFS, and ECMWF
models were in fairly good agreement and used for the short term
forecast. Changes were made to the location of the low pressure
system in the eastern gulf Sunday and Sunday evening primarily
based on the GFS and ECMWF models.

.LONG TERM.../Sunday through Friday/ Models still struggling with
weekend system so basically left Sun and Sun night forecast as is.
For Mon onward, did use latest WPC for the most part. Looking more
likely that another low will move across the area Mon into early
Tue, but models differ on track and strength. WPC seemed like a
good compromise. Later in the week, large system will likely
affect the area for mid to late week. Still some low track details
to work out with this system. This system will most likely have
remnants of Typhoon Lan embedded, which increases potential for a
powerful storm. Overall, a wet long range period is in store for
the area.

System moving in Mon into early Tue may bring some fairly heavy
rain and strong winds with it to the S of the main low track.
Another concern with this system is potential for a snowmelt
cooling event in the deformation zone to N of low track Mon night
into early Tue. Still plenty of time for these issues to be
resolved.

The mid to late week system looks very wet and windy given
infusion of tropical moisture/energy. Evolution of sfc low
development will play a big role in where and when heaviest rain
and strongest wind will occur. Models have been all over the place
on this so confidence in the details remains on the low side.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind from Saturday morning through Saturday afternoon for
     AKZ027.
     Strong Wind from Saturday morning through Saturday afternoon for
     AKZ023.
MARINE...Storm Warning for PKZ041.
     Gale Warning for PKZ035-036-042-043.
     Small Craft Advisory for PKZ013-021-022-032>034-051-052.

&&

BM/RWT

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