Area Forecast Discussion
Issued by NWS
FXAK67 PAJK 090018
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
318 PM AKST Thu Dec 8 2016
.SHORT TERM...Strong cold high pressure over northwest and western
Canada is the dominant feature that will be impacting Southeast
Alaska through Friday. With the pressure gradient differences
increasing out to gulf coast locations, the increase in the
outflow winds is the biggest forecast issue. Winds up to max gale
force in northern part of Lynn Canal, and out interior river
valleys. Gusts increasing to 50 to 60 kt over the water.
In the Juneau local area a Taku mountain wave event will develop
overnight so Douglas and downtown Juneau will see gusts up to 60
mph tonight into Friday and the event will continue into the
weekend. Will be upgrading the High Wind Watch to a Warning
starting Thursday evening.
The cold air temps in the minus teens and strong winds of 20 to
30 mph flowing through White Pass, believe it will be sufficient
for a Wind Chill Advisory for the White pass area. Expect wind
chills of -30 to -45 from tonight and lasting to roughly midday
.LONG TERM...Still looking cold and dry for much of the upcoming
week. High pressure will persist over NW Canada into the middle of
next week, with upper ridge generally remaining W or NW of the
area. The ridge will evolve from a closed off upper high over the
NW part of AK to a sharp ridge that extends from the NE Pacific N
into mainland AK by the middle of next week. Looks like the
weekend will be the coldest period with some moderating temps
early next week. Models differ on potential for another shot of
colder air for mid to late next week, so temps were generally kept
in middle of model forecasts for that period.
Kept Taku winds going through midday Sat around downtown Juneau
and Douglas. There is potential that they could last a little
longer than that but it will depend on critical level. Raised seas
for Lynn Canal and parts of N Stephens Passage/E Icy Strait/N
Chatham Strait as long duration N gales will maintain large
swells. Had highest seas over S Lynn Canal where fetch will be
maximized for the N winds and before the channel splits. Showed
the seas decreasing as they continued S out of Lynn Canal.
Freezing spray will remain an issue over mainly the N area,
although some may occur as far S as Sumner Strait this weekend as
colder air filters into the southern area.
.AVIATION...VFR conditions for the next few days, although the
hazard will be Turbulence due to strong outflow winds along
channels and over terrain. Wind shear near some of the airports,
and turbulence near the terrain. Mountain waves developing near
the coast mountains headed into the weekend.
.MARINE...The strong outflow winds means the strongest winds for
Southeast Alaska will be over the inner channels near the interior
passes and river valleys along the with exit regions into the gulf
of alaska. Look for strong gales to developing across lynn Canal
late tonight and Friday. Seas picking up and building into the
lower teens for the southern Lynn canal.
PUBLIC...High Wind Warning from 9 PM this evening to noon AKST Saturday
Strong Wind from midnight AKST tonight through Friday evening
Strong Wind through Friday evening for AKZ018.
Wind Chill Advisory from midnight tonight to 11 AM AKST Monday
MARINE...Heavy Freezing Spray Warning for PKZ012.
Gale Warning for PKZ012-013-021-022-031-035.
Small Craft Advisory for PKZ011-032>034-036-041>043-051-052.
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