Gale Warning 140, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
610 AM AKDT Tue Apr 10 2018

.SHORT TERM...A strong low over the western gulf has a large
occluded front wrapped around it and extending over the eastern
gulf. The low center will remain on the west side of the gulf and
start to weaken today. A wave along the front is causing a new
low to form south of Haida Gwaii as seen on satellite imagery as
of 530am. This feature looks to track across the eastern gulf
outside waters, starting near Dixon Entrance late Tuesday
afternoon and ending up over the north-central gulf by Wednesday
morning. In general, models came into better agreement on this new
low center developing and tracking quickly across the area.
Therefore have increased winds speeds quite a bit to reflect this
new thinking. Majority of the panhandle will see wind gusts of
35-45mph for a short period of time. Some places along the outer
coast, including Port Alexander and portions of POW Island could
see higher gusts. Peak winds for the southern inner channels look
to be during the late afternoon and in the early evening for S.
Baranof Island. The Icy Strait area, including Tenakee Springs,
will get into the action in the late evening. Yakutat can expect
strong gusts overnight and into the pre-dawn hours.

Expect rain to be pretty spotty today, especially over the
northern panhandle. The southern areas will see the threat of rain
increase as the low approaches in the afternoon. Rain will spread
across the region tonight, but similarly to the wind, will be
moving in/out quickly. Cloudy skies and gusty winds through
tonight will likely keep the diurnal temperature range smaller
than we've seen as of late, likely less than 10 degrees. This area
of the forecast was not given as much attention.

On Wednesday expect more breaks in the cloud cover and a lower
chance of rain. There will continue to be multiple lows in the
gulf, rotating about a larger parent low, but overall flow across
the panhandle will become more offshore.

While the model upper level pattern is fairly similar,
there are differences with strength near the surface for today's
low. Initially the ECMWF looks to be the strongest/fastest, the
Canadian is the slowest to move the feature through but is also
fairly strong. The new 6z NAM came into better agreement with the
GFS which was in the middle as far as placement goes. Ended up
using primarily the GFS with some NAM for changes to the low
placement and to increase wind speeds. The ECMWF and Canadian
models had the low center closer to shore, this would result in
stronger winds. This system will be closely monitored for
more/less development or for position changes.

.LONG TERM /Thursday through Tuesday/...As of 10pm Sunday.
Remnants of the mid/upper trough currently over the extreme
southern Gulf will wind up along the southern Panhandle coast by
early Thursday. Part of this energy will likely be pulled N and
then W around a second closed mid/upper trough which will
establish itself over the south central Gulf by Thursday night.
Operational models and their ensembles continue to differ in the
details of individual fronts and pieces of energy rotating
northward around this trough through early Saturday. Most likely
places to receive continued rainy conditions and periods of gusty
wind from Thursday through Saturday will be the southern
Panhandle, although most of the Panhandle will probably see
rainfall on Friday as the main upper trough begins to get kicked
east. The biggest disagreement in model-land centers around what
happens with the Arctic stream trough forecast to drop southward
through the Yukon and interior of Alaska on Friday and Saturday as
ridging builds over the Bering Sea. Timing and position of this
feature will likely determine how quickly the low level flow gains
an offshore component this weekend and the resultant drying.
Eventually though, it looks like a drier period will begin to set
up by Sunday into Monday.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind from 4 PM AKDT this afternoon through this evening
     for AKZ026>028.
     Strong Wind from 1 PM AKDT this afternoon through this evening
     for AKZ025.
     Strong Wind from this evening through late tonight for
     AKZ021>023.
     Strong Wind late tonight for AKZ017.
MARINE...Gale Warning for PKZ022-032-033-036-041>043-051-052.
     Small Craft Advisory for PKZ011>013-021-031-034-035-053.

&&

Ferrin/DEL

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Special Weather Statement
National Weather Service Juneau AK
622 AM AKDT Tue Apr 10 2018

AKZ017-021>023-025>028-101630-
Cape Fairweather to Cape Suckling Coastal Area-
Eastern Chichagof Island-
Salisbury Sound to Cape Fairweather Coastal Area-
Cape Decision to Salisbury Sound Coastal Area-
Juneau Borough and Northern Admiralty Island-
Inner Channels from Kupreanof Island to Etolin Island-
Dixon Entrance to Cape Decision Coastal Area-
Southern Inner Channels-
Including the cities of Yakutat, Hoonah, Elfin Cove, Pelican,
Sitka, Port Alexander, Juneau, Petersburg, Wrangell, Kake, Craig,
Klawock, Ketchikan, and Metlakatla
622 AM AKDT Tue Apr 10 2018

...FAST MOVING GALE FORCE LOW TO AFFECT THE PANHANDLE TUESDAY...

A strong gale force low is forming this morning south of Haida
Gwaii and west of Vancouver Island. This low will deepen rapidly
as it tracks north today and will pass close by the southern outer
coast late this afternoon. The low will then track northwest into
the central gulf late tonight. A very tight pressure gradient
combined with the proximity to the panhandle will result in an
area of strong winds to progress from south to north through the
period.

Because this system is moving so quickly, the period of strongest
winds for any given location will last only 3 to 6 hours. At this
time, peak wind gusts are forecast to be 45 mph. However, there is
a moderate level of uncertainty with the track and strength of
this low, and higher winds cannot be ruled out at present.
Therefore, residents of Southeast Alaska are urged to remain
alert for updates to the forecast as the day progresses.

Special Weather Statement
National Weather Service Juneau AK
632 AM AKDT Tue Apr 10 2018

AKZ017-021>023-025>028-110200-
Cape Fairweather to Cape Suckling Coastal Area-
Eastern Chichagof Island-
Salisbury Sound to Cape Fairweather Coastal Area-
Cape Decision to Salisbury Sound Coastal Area-
Juneau Borough and Northern Admiralty Island-
Inner Channels from Kupreanof Island to Etolin Island-
Dixon Entrance to Cape Decision Coastal Area-
Southern Inner Channels-
Including the cities of Yakutat, Hoonah, Elfin Cove, Pelican,
Sitka, Port Alexander, Juneau, Petersburg, Wrangell, Kake, Craig,
Klawock, Ketchikan, and Metlakatla
632 AM AKDT Tue Apr 10 2018

...FAST MOVING GALE FORCE LOW TO AFFECT THE PANHANDLE TUESDAY...

A strong gale force low is forming this morning south of Haida
Gwaii and west of Vancouver Island. This low will deepen rapidly
as it tracks north today and will pass close by the southern outer
coast late this afternoon. The low will then track northwest into
the central gulf late tonight. A very tight pressure gradient
combined with the proximity to the panhandle will result in an
area of strong winds to progress from south to north through the
period.

Because this system is moving so quickly, the period of strongest
winds for any given location will last only 3 to 6 hours. At this
time, peak wind gusts are forecast to be 45 mph. However, there is
a moderate level of uncertainty with the track and strength of
this low, and higher winds cannot be ruled out at present.
Therefore, residents of Southeast Alaska are urged to remain
alert for updates to the forecast as the day progresses.