Gale Warning 276, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
225 PM AKST Mon Dec 24 2018

.SHORT TERM.../Through Wednesday night/ Upper trof over the
eastern gulf will move inland tonight. Fairly strong vort maxima
will move across the central panhandle this evening. Weak upper
ridging will move in for Tue, then push E of the area Tue evening.
A strong upper trof with several embedded shortwaves will move
into the gulf Tue, then weaken and drift E through Wed night. At
the sfc, main features of concern will be a strong low and front that
move into the eastern gulf Tue night. Model agreement on these
features is much better through Wed, but some differences remain
with where they move after Wed. Think low will drift E across the
central panhandle Wed night while rapidly weakening, while the
front slowly dissipates Wed into Wed night over the eastern gulf
and central panhandle. Preferred the 12z GFS to handle the main
features, with 18z NAM and the latest ECMWF close to that
solution.

Keeping out the winter weather advisory for the Juneau area this
evening, as a band of heavier snow showers will move through with
the strong vort maxima. Think much of the snow and rain showers
will diminish from the W tonight as upper trof moves inland and
depth of unstable layer decreases. Still may be some leftover rain
and snow showers Tue, which may increase some in coverage as upper
trof and front approach from the SW. Main frontal precip will
reach the southern area Tue afternoon, then spread slowly N Tue
night into Wed. With main low center staying S of 58N, think the
far N area will have some trouble getting into any significant
precip due to offshore flow and a weakening front. Does look like
a second wrap of the front will come ashore Wed, which could
spread some precip a bit further N. Not planning on any winter
weather headlines with the Tue night-Wed precip over the N-central
area, as temps will be marginal for all snow. Will need to watch
deformation band on N side of low moving onshore, for potentially
significant snow later Wed afternoon into Wed night over the
N-central area.

Winds will be fairly strong ahead of the initial occluded front
and with second wrap of front. Think a band of storm force winds
are likely over the eastern gulf Tue night with the first front.
The second wrap of front may have close to storm force winds as
well. Have kept in strong wind headlines for Tue afternoon for the
outer coast from Sitka southward, and they will likely continue
into Tue night in these areas. May need strong wind headlines for areas
further N and E, with main area of concern over the S half of the
inner channels. Another round of strong winds may accompany the
second wrap of the front along the central outer coast Wed. Winds
should drop off rapidly late Wed into Wed night as low fills
quickly as it moves inland.

.LONG TERM.../Thursday through Sunday/...Active weather pattern
is likely to continue through the mid-range forecast. By Thursday
an upper ridge should move over the panhandle with a strong upper
jet streaming in on the backside of the ridge directed towards SE
Alaska. Another trough may then move into the Gulf but models
differ with exact timing, depending on how robust the ridge
becomes over the panhandle. But do expect a progressive pattern to
persist through the end of the week.

A strong front with the possibility of higher amounts of
precipitation could move across the panhandle later Thursday
enhanced by the upper jet. Temperatures look to warm Thursday so
the rain/snow line may move back northward. With the uncertainty
that still exists in the long range did not make too many
adjustments to the forecast after Thursday, nudging toward a WPC
ensemble solution through the weekend.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind Tuesday afternoon for AKZ023-027.
     Winter Weather Advisory until 9 PM AKST this evening for AKZ025.
MARINE...Gale Warning for PKZ041>043-051.
     Small Craft Advisory for PKZ012-013-022-033-035-036-052.

&&

RWT/DDH

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