Area Forecast Discussion
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000
FXAK67 PAJK 151422
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
522 AM AKST Fri Feb 15 2019

.SHORT TERM.../Through Saturday night/ The main story of the short
range continues to be the outflow winds that persist across the
northern half of the panhandle. Highest observed winds have been
at Little Island in southern Lynn Canal with sustained of around
50 kt with gusts reaching hurricane force overnight. Winds of 25
to 35 kt have also been observed in other outflow areas overnight
(Eldred Rock, Cape Spencer, Point Arden, and Five Fingers to name
a few). Gusts in excess of 60 mph have also been observed near
Downtown Juneau and Douglas prompting the issuance of a high wind
warning for that area through 4 pm this afternoon.

Over the next 48 hours, the outflow will continue in the usual
areas. However, it will be gradually diminishing as first the
inverted trough over the area gradually weakens, and second the cold
high in the Yukon will begin to pull away to the east Sat
afternoon. This will result in a gradual weakening of pressure
gradients along the coast mountains and a gradual reduction of
cold air spilling through the mountain passes. Gale force winds
will likely still be felt in Lynn Canal through at least early
Sat, and winds of 25 kt are expected to last into Sat afternoon
for many northern inner channel areas.

Gusty winds will also still be observed at downtown Juneau and
Douglas due to taku winds through the period. Though with
gradually diminishing cross barrier flow, the gusts to 60 mph are
not expected past late this afternoon.

Signs of change at the end of the short range as a front starts to
try to push through the ridge over the gulf Sat night. This will
increase winds and precip chances in the central gulf, but that is
about it through Sat night.

Most changes in the short range relegated to local effects from
the outflow. Nam was the main guidance used.

.LONG TERM.../Sunday through Friday as of 10 pm Thursday/
Longwave pattern aloft will feature upper ridging over the far
EPAC and gulf of AK, while upper trof remains across the N-central
PAC and the Bering Sea. A series of shortwave trofs will move
across the top of the ridge into SE AK through the period, but big
question will be how strong they will be by time they reach the
forecast area. First significant shortwave looks like it will move
across the area Sun night and Mon morning. Another shortwave will
likely track E across the gulf and SE AK Mon night and Tue. After
that, model differences increase on following systems. GFS is
faster than Canadian/ECMWF bringing in a system for midweek. Did
make some forecast adjustments with the above in mind.

First change was to slow onset of precip Sun into Sun night.
Models have slowed the precip development some as upper ridge is
being maintained stronger initially. Eventually, precip should
move in with first shortwave later Sun into Sun night. With the
expected precip/cloud cover Sun night, temps were bumped upward
for then as very little drop is expected during the night. POPs
were raised as well Sun night into Mon with good model agreement
on the strength of the shortwave moving through. Could be a decent
snowfall over the eastern and northern areas with this system, but
too early to tell exactly how much snow will fall.

There may be a brief break in the precip before next system
arrives Mon night. Once again, temps were raised during the
nighttime period as minimal cooling is expected with system moving
through. Did bump POPs up a bit as well for Mon night into Tue.
The rain/snow line will likely drift further inland and northward
with this system as well. Could end up being a decent snowfall
with this system closer to the Coast Mtns and across the northern
area.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning until 4 PM AKST this afternoon for AKZ025.
     Strong Wind from 4 PM AKST this afternoon through late tonight
     for AKZ025.
     Strong Wind through this afternoon for AKZ018.
MARINE...Storm Warning for PKZ013.
     Gale Warning for PKZ012.
     Small Craft Advisory for PKZ021-022-031>034-041>043-051.

&&

$$

EAL/RWT

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