Area Forecast Discussion
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798
FXAK67 PAJK 171450
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
550 AM AKST Fri Nov 17 2017

.SHORT TERM.../Through Saturday night/Pretty much kept current
forecast going through Saturday night. Complex low over the gulf
will eventually move SE of the area by Saturday evening. Still
some tricky aspects of the forecast to deal with as multiple
shortwaves move around the complex low into SE AK. Current
thinking is there will be some enhancement to the snow around the
Juneau area this afternoon and early evening as a shortwave rides
NE across the area. The only change made to the headlines was to
extend the WW advisory for Yakutat until 18z as they will be under
deformation band until then.

Winds will shift around to the N over the northern area this
morning, and pick up to gale force over Lynn Canal by late
afternoon. The northerly wind shifts will spread to the central
channels tonight. This will also bring some cooler air back into
the area tonight. Outflow will increase over the NE gulf late this
afternoon and tonight as complex low shifts SE of there and high
pressure builds over the Yukon. These stronger winds should last
into Saturday night.

.LONG TERM.../Sunday through Friday/Increasing anticyclonic flow
from the west will support clearing skies and more cold air
sliding from the north on Sunday. We lowered low temperatures for
Sunday morning and the high temperatures Sunday afternoon and
dried the forecast for all but the far southern Panhandle as
scattered snow showers exit. But late Sunday we begin to see the
next system move into the central gulf. We have raised easterly
winds across the gulf to gales by Sunday night with the option to
continue through Monday. Many eyes on land will be looking for
more snow to develop across portions of the Panhandle. However,
increasingly, an east-west orientation of the associated front
may limit snow in the north and north-central Panhandle and focus
precipitation in the south and south-central areas. And any
potential wave development along the front would exacerbate this
trend. So currently, we expect 2 to 6 inches across the north and
central Panhandle and up to 2 inches with some rain over the
south including Sitka for the period of Monday and Monday night.
However, as the time period begins to fall in range of our higher
res models, we may need to back off these totals especially in the
Juneau area where downsloping tends to dry the atmosphere.

We made little change Tuesday and Wednesday given poor
consistency of models. But should trends hold, we may allow our
gulf low to drop to the south, therefore, keeping the north drier
and potentially cooler than our current forecast with some rain or
snow in the south.

Ensembles do point to a potential pattern shift toward the
Thanksgiving Day holiday weekend. Temperatures begin to rise more
toward seasonal levels which would advance the snow-rain line
northward well into the central Panhandle. We did nudge
temperatures upward Thursday and Friday into the low to mid 30s
for much of the northern Panhandle. Be forewarned that our
temperatures may support rain as far north as Juneau, but
confidence is not great enough to make this move yet.

Confidence is average Sunday into Monday and generally falls mid-
week. However, we were confident enough to raise temperatures and
turn Inner Channel winds southerly Thanksgiving Day into Friday.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Weather Advisory until 4 PM AKST this afternoon for
     AKZ026.
     Winter Weather Advisory until noon AKST today for AKZ024.
     Winter Storm Warning until 9 PM AKST this evening for AKZ025.
     Winter Storm Warning until noon AKST today for AKZ022.
     Winter Storm Warning until 4 PM AKST this afternoon for
     AKZ019>021.
     Winter Weather Advisory from 9 AM this morning to 9 PM AKST this
     evening for AKZ029.
     Winter Weather Advisory until 9 AM AKST this morning for AKZ017.
MARINE...Gale Warning for PKZ012-013-022-031-043-051.
     Small Craft Advisory for PKZ011-021-032>036-041-042-052-053.

&&

$$

RWT/JWA

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