Area Forecast Discussion
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424
FXAK67 PAJK 081512
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
612 AM AKST Thu Dec 8 2016

.SHORT TERM...Satellite imagery and surface analysis indicate a
dissipating low over the W gulf with a trough rotating counter
clockwise around the low. This trough will provide focus for lift
for SN continuing along the N gulf coast for the next few hours
before diminishing. Therefore, elected to extend the winter wx
advisory through 8AM for AKZ017 but trend remains for diminishing
snow showers this morning. Next forecast challenge will be winds.
Nly/outflow winds will begin to rise this evening as low pressure
dissipates and high pressure builds back into the region from BC.
Continue to expect winds to increase to gales by late afternoon
over Lynn Canal with at Skagway reaching near 40 mph. Winds will
continue to increase overnight with potential for Taku wind to
develop late tonight/early Fri morning and a HWW is in effect. As
winds increase, the threat of freezing spray develops over the
inner channels. Current forecast represented this well, so only
made some minor adjustments where winds were adjusted. Final
concern during this period is regarding fog. MOS guidance
indicates fog developing across most of SE tonight into early Fri,
but with BL RHs pretty low in short range guidance confidence is
too low to mention attm.

.LONG TERM...The extended forecast is a persistent clear and cold
pattern with northerly outflow winds. Temperatures aloft remain
cold enough for any precip to be all snow, however the only precip
potential looks to be ocean effect snow showers over the gulf near
outflow areas. Temperatures at White Pass fall into the negative
teens at night and resulting wind chills cloud be as low as 35-45
below zero. Advisory level wind chills (-30F) look to persist
until temperatures warm some next week. Cold temperatures and
strong winds will also make for favorable conditions for freezing
spray near northern interior passes.

Potential for a Taku Wind event starting Friday morning and lasting
into Saturday morning as stated above. All ingredients are
looking favorable with a peak Friday night. The NAMnest is
indicating wind gusts of 60-70mph during this timeframe, so have
issued a High Wind Watch for Downtown Juneau and Douglas.

Forecast confidence on the dry/cold pattern is above average but
somewhat lower on other details such as cloud cover and temps in
windy spots.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Watch from Friday morning through Saturday morning for
     AKZ025.
     Strong Wind from this evening through late tonight for AKZ025.
     Strong Wind from 6 PM AKST this evening through late tonight for
     AKZ019.
     Strong Wind through Friday afternoon for AKZ018.
     Winter Weather Advisory until 8 AM AKST this morning for AKZ017.
MARINE...Gale Warning for PKZ012-013.
     Small Craft Advisory for PKZ011-021-022-031-033>036-041>043-
     051>053.
&&

$$

BC/Ferrin

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