Small Craft Advisory 673, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
427 PM AKDT Thu Nov 3 2016

.SHORT TERM...Satellite imagery is showing the storm force low
from earlier today over the northeastern gulf and tracking
northwest while weakening. Plenty of lightning has been observed
as well with some strikes occurring over the inner channels. As
this low continues off to the northwest while weakening, another
storm force low will approach from the south and follow a very
similar track. Morning and afternoon models differ on details of
the track, which can result in significant differences in the
resulting winds over the panhandle. As it is, 850 mb jet core in
excess of 80 kts suggests high winds will occur again tomorrow.
The current forecast reflects this and will result in another
high wind event for the southern outer coast and over the southern
inner channels. Additionally, storm force southerlies will
develop over Clarence Strait and the southern coastal marine zones by
tomorrow afternoon. Strong wind gusts to 40 mph also anticipated
for zone 26 and again in the downtown Juneau/Douglas area.

Rain/showers have been moderate to heavy at times through the day
today and more of the same is expected with the next low/front.
CAPE and LI values also indicating thunderstorms are once again
likely and have included this element in the forecast as well.
Temperatures on the Klondike and Haines Highways adjusted down
based on observations and now have snow in the forecast for both
roadways for tonight. Snow changing to a rain/snow mix on the
Haines Highway by tomorrow afternoon. Amounts below advisory
level.

Updates to pressure weighted in favor of 12Z GFS. Modifications
to winds based on upper level jet strength. No significant changes
to PoP or QPF. Changes to temperatures limited to the highways.
Overall forecast confidence is average.

.LONG TERM...Storm force low discussed above is forecasted to
progress northward across the eastern gulf through Friday night
and be west of Sitka around midnight. Except showers to be
moderate to heavy at times into Saturday morning. Strong wind
gusts of 40-55mph will continue through the Friday night from
Ketchikan to Elfin Cove with strongest winds along the outer
coast. As the low moves to the north winds will shift to the SW
with similarly strong gusts for POW and Baranof Islands. Models
have differed quite a bit on low placement and even minor shifts
will result in different timing of wind shifts etc. Have gone with
an average of the ECMWF and GFS for this forecast package with an
emphasis on the 12z GFS. This slowed things down slightly and
moved the low center inland near Pelican Saturday morning. As the
low moves inland, N winds through the northern inner channels will
diminish then quickly increase out of the south Saturday
afternoon.

Through the next week the forecast continues to be very active
with multiple low centers following a similar path to the previous
ones. This will keep things on the warm side with rain likely
most days. Currently have another gale force system for Sunday
night and another Wednesday. Timing and details of each system
will be fine tuned each day.

&&

.AVIATION...Brief break in widespread LLWS and mod to severe
turbulence overnight, but conditions expected to deteriorate once
again tomorrow. Definitely not good flying weather.

&&

.MARINE...Areas of the eastern gulf will see winds 90 degrees off
the prevailing southerly swell train, so combined seas will not
be quite as steep-faced as today. Still, seas up to 28 feet have
been measured by buoy 46205 and prevailing swell period over the
gulf has been around 14 seconds. Little change change to the high
seas situation over the gulf during the next 24 hours.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...STRONG WIND from Friday morning through Friday afternoon for
     AKZ026.
     High Wind Warning from 10 AM to 4 PM AKDT Friday for AKZ027-028.
     STRONG WIND from Friday morning through Friday afternoon for
     AKZ025.
MARINE...Storm Warning for PKZ036-041-042.
     Gale Warning for PKZ022-031-033>035-043-051.
     Small Craft Advisory for PKZ012-013-021-032-053.
     Small Craft Advisory due to Seas for PKZ052.
&&

Fritsch/Ferrin

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