High Wind in Alaska, November 13 to 14, 2017

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
235 PM AKST Mon Nov 13 2017

.SHORT TERM...Through Wednesday night. Strong outflow winds
continue to be the main forecast concern. Gale force winds are
currently being observed in many northern inner channels marine
areas. The strongest winds are in northern Lynn Canal where
Eldred Rock has winds of 45 kt with gusts to 60 kt. Outflow is
expected to continue through Wednesday night with the highest
winds expected tonight when northernly pressure differences reach
their maximum (around 12 mb of pressure gradient is expected
between Juneau and Skagway). Gale force winds expected to continue
with storm force winds expected in Lynn Canal tonight. Strong
wind headlines also remain up for Skagway and Yakutat (out of
interior passes) for gusts to 40 mph or more. The combination of
the high winds and cold temperatures may also cause some freezing
spray in the northern inner channels during this period.

A high wind warning remains up for the downtown Juneau and Douglas
area tonight into tomorrow morning for a strong Taku wind event.
Maximum cross barrier flow of around 45 to 50 kt is expected late
this evening and will continue into Tuesday morning while a
noticeable inversion is in place. The critical level is also
looking decent with directional shear showing up around 500 mb
for most of the night. Gusts are expected to reach around 65 mph
with the highest winds expected overnight. These higher winds
could last into Tuesday afternoon but the critical level could
start to rise and cause winds to diminish at that time so we still
have the warning expiring mid day Tuesday.

Other then the winds, forecast is rather quiet with mostly cloudy
to mostly clear skies and dry weather for many areas. Southern
panhandle will be the receiver of the most clouds and maybe some
showers as the last weak frontal bands from the low west of Haida
Gwaii moves north tonight into Tuesday. Light precip expected
as there is little moisture for the front to work with and even
that far south it will be fighting the outflow. The bands will
not make it that much further north than Sumner Strait as the
strong outflow will tear the bands apart.

Short range models in good agreement with mainly some minor
differences noted in the low west of Haida Gwaii and the
associated frontal bands. Overall changes were mostly limited to
local effects for the winds. Main Guidance was Nam with some GFS.

.LONG TERM.../Wednesday through Monday/...Extended range forecast
begins with a deep upper trough extending from the Yukon south
across the panhandle and over the eastern Pacific west of
washington State. Associated closed circulations aloft and at the
surface will be located south of Haida Gwaii and west of Vancouver
Island. Upstream, a sharply defined upper level ridge will be
moving over the western interior. A 100 kt 500mb northerly jet
downstream of the ridge axis will shift east to be over the
panhandle by Thursday morning. Across the interior and
northwestern Canada, strong surface high pressure will have built
in and be shifting east. 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 -15C by mid to late
week, which represents more than 2 standard deviations below
normal. Once again, temperatures across the panhandle were
adjusted down from Wednesday through the weekend using bias
corrected AKMOS for guidance. Based on current model spectrum
spread, additional adjustments will probably not 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.

Chance PoPs re-enter the forecast by Friday, getting up to likely
Pops Friday night and Saturday night for the southern zones. Precip
type will be a rain/snow mix for the southern outer coast and
Ketchikan area, with snow elsewhere. the Rain/snow mix line will
migrate as far north as Frederick Sound Saturday night, but then
shift south again on Sunday.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning from 6 PM this evening to noon AKST Tuesday
     for AKZ025.
     Strong Wind through late Tuesday night for AKZ018.
     Strong Wind through late tonight for AKZ017.
MARINE...Storm Warning for PKZ012.
     Gale Warning for PKZ011-013-022-031-032-034-043-051.
     Small Craft Advisory for PKZ021-033-035-041-042-053.

&&

EAL/Fritsch

Visit us at http://www.weather.gov/Juneau