Gale Warning 250, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
344 PM AKST Sun Nov 12 2017

.SHORT TERM...Through Tuesday night. Outflow winds continue to be
the main feature of the short range period. Currently outflow has
weakened in response to a upper trough that is dropping SE
through the area, through winds of 20 to 25 kt are still blowing
in Lynn Canal and Cross Sound. This weakening is not expected to
last as the winds will begin to increase late tonight with gales
in northern marine areas and gusty winds out of interior passes
again as early as Monday. Small craft advisories, gale warnings,
and strong wind headlines will once again be hoisted and may
continue into mid week at least. Freezing spray may also become an
issue with the high winds and cold temperatures in the northern
inner channels.

There are indications for a strong Taku Wind event developing for
downtown Juneau and Douglas Monday night. Cross barrier flow is
forecast to reach 50 kt Mon night with an inversion likely from
the cold air outflow. The critical level looks good as well with
directional shear showing up between 400 and 600 mb on Nam
forecast soundings. Decided to issue a high wind watch for Monday
night and Tuesday for the potential for gusts to 65 mph.

In addition to the outflow, a low near Dixon Entrance is trying to
send a few weak frontal bands northward through the next few days.
The only one that will have some success is the one currently over
the southern panhandle right now. The decreased outflow across the
north tonight will allow the weak front to stay together enough to
bring the possibility of snow showers as far north as Hoonah and
Juneau late tonight. Accumulations are expected to be low as
there is very little moisture for the front to work with and the
remaining outflow will still be trying to tear it apart. Any
other frontal bands will not make it out of the southern panhandle
with the strong outflow keeping the rest of the panhandle rather
dry through mid week.

Guidance continues to be rather good through some differences were
noted with the low near Dixon Entrance. Most changes from the
previous forecast were for local effects for outflow winds. Main
guidance was the Nam with ECMWF.

.LONG TERM.../Tuesday through Sunday/...A deep upper trough with a
vertically stacked closed circulation aloft and at the surface
will be located west of Haida Gwaii at the start of this long
range forecast period. Upstream, there will be a sharply defined
upper level ridge. Across the interior and northwestern Canada,
strong surface high pressure will have built in. Net effect of
these features will be a continuation of strong northerly outflow
winds and temperatures well below normal for mid November.

850 mb temperatures will be dipping down to -14C by mid to late
week with the far northern inner channels closer to -20 degrees
C, which represents more than 2 standard deviations below normal.
Followed suit with the trend in the previous long range forecast
by lowering temperatures further using bias corrected AKMOS for
guidance. Based on current model spectrum spread, additional
adjustments down may be necessary.

Second major weather element of note in this long range forecast
period will be sustained strong northerly outflow winds. Gales
will continue for the inner channels from Frederick Sound north
for most of the upcoming week. High end small craft
northeasterlies on Yakutat Bay will increase to gales by mid week.
Elsewhere on the northeast gulf coast east of Yakutat and down to
Cross Sound, northeasterly outflow gales will extend well out into
the gulf...also lasting most of the upcoming week.

With the wind and cold temperatures, there will be areas of
freezing spray over the northern inner channels and blowing snow
over higher elevations.

PoP not much of a concern for this coming week. Southern locations
are most likely spots to see any precipitation, and then only a
chance for anything on Tuesday and then again Thursday night
through Sunday. Precip type on Tuesday, if any occurs will
probably be a rain/snow mix. By the weekend, expect any precip
that does fall to be snow.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Watch from Monday evening through Tuesday morning for
     AKZ025.
     Strong Wind until 3 PM AKST this afternoon for AKZ018.
     Strong Wind from late tonight through late Monday night for
     AKZ018.
     Strong Wind from Monday morning through Monday afternoon for
     AKZ017.
MARINE...Gale Warning for PKZ012-013-022-043-051.
     Small Craft Advisory for PKZ011-021-031>035-042-053.
     Small Craft Advisory due to Seas for PKZ041.

&&

EAL/Fritsch

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