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FXAK67 PAJK 171401

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
601 AM AKDT Tue Oct 17 2017

.SHORT TERM...The persistent low south of Icy Bay will finally
fill today. Weak ridging briefly forms over the Panhandle this
afternoon but is quickly pushed aside as the next low and
associated front moves in from the west. The low will just skirt
the southern marine areas, but the wind affects of the front will
impact much of the Panhandle and eastern gulf. The good news is
this system is quick, the bad news is that the system is strong.

Gale force winds will develop in the southern area of marine zone
310 early this evening and spread quickly over the outer coastal
zones from south to north. By late tonight the southern outer
coastal area off of Prince of Wales will already have diminished
to SCA criteria. The strongest winds will define the front as it
approaches the Panhandle and then a smaller area will rotate
counter clockwise around the low late tonight and Wednesday, as
the front becomes occluded. Strong wind headline for the western
side of Prince of Wales late tonight/early morning Wednesday with
gusts increasing to around 40 mph after midnight. With the speed
of this system the strong gusts will only last a few hours and
will be 35 mph or less before sunrise.

Cold air aloft and warm gulf waters have continued to produce
unstable air, resulting in a few lightning strikes near Biorka
Island overnight. As I write this, an area on chichagof Island had
three strikes in a line from Lake Anna to Whitestripe Mt. to the
north. Slight chance of thunderstorms will continue this morning
near the coastal areas from around Cross Sound down to Prince of

Widespread rain showers will change over the rain with this strong
front during the overnight hours. Snow levels are around
1000-1500 feet for Skagway and Haines areas, giving the highways
some minor snow accumulations.

Model agreement between the GFS/NAM and Canadian NH for today was
good and then the GFS and NAM were used where needed. Made some
updates to wind/seas, also lowered temperatures a degree or so for
the next couple of days. Overall, the forecast needed little work
to the big picture and minor updates on a local scale.

.LONG TERM.../Thursday through Tuesday/Little change made to
longer range forecast. Models in generally good agreement on the
large scale features but have important differences on smaller
scale features. Main system of concern in long range is a complex
low expected to move into the gulf by the weekend. Models hint at
a deeper system than current forecast shows but have important
detail differences that make it impractical to change much right
now. Still plenty of time to make adjustments on this system since
we are talking 4-5 days out.

Otherwise, pattern will remain on the cool and wet side for much
of the time. Still looks like any airmass cold enough for snow
near sea level will stay W of the area through at least early
next week. Later next week, will need to monitor a system that
could have the remnants of tropical cyclone Lan embedded with it.


.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind from late tonight through Wednesday morning for
MARINE...Gale Warning for PKZ041>043-051-052.
     Small Craft Advisory for PKZ021-022-033>036.




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