Gale Warning 94, NWS Juneau, AK

Southeast Alaska Forecast Discussion...CORRECTED
National Weather Service Juneau AK
438 PM AKST Wed Feb 28 2018

.SHORT TERM.../Wednesday night through Thursday night/...A low
over Haida Gwaii will slowly weaken and move south through this
short term forecast period, taking rain and snow showers with it.
A trough of low pressure will remain over the far eastern gulf and
high pressure over the interior and western gulf will shift east
through the period, resulting in very strong outflow winds along
the central and northern outer coast as well as the northern and
central inner channels. Storm warnings in effect for northern and
southern Lynn Canal tonight as well as out of Cross sound tomorrow
morning. As winds over the northern inner channels shifted north,
temperatures fell rapidly over the canal, prompting a heavy
freezing spray warning for tonight over northern Lynn. Freezing
spray also expected in Stephens passage, Glacier Bay, Yakutat Bay
and coastal marine zones 51 and 52. Strong winds in the Yakutat
zone are expected, but really only east of town. Strong winds also
forecast for Skagway with blowing snow along the Klondike
Highway. Mountain wave guidance for Taku Winds in the
Juneau/Douglas area are still clearing suggesting high winds from
late this evening through late Thursday evening. Look for
northwest winds 20 to 30 mph to become northeasterly and increase
later this evening.

Strong cold air advection is forecast in the very low levels. This
signal is quite strong at 925 mb, though not so pronounced at
850mb, indicating that the Arctic front will push south out of
Canada and over the panhandle in the short term. Look for
overnight lows to be quite a bit colder tonight as compared to
Tuesday night. Outflow winds will also result in clearing skies
and while some solar warming is expected on Thursday, it will
still be a bit colder than Wednesday.

Previous forecast remains on track and in good shape, so little in
the way of changes today. Overall forecast confidence in very
windy conditions, dry weather and colder conditions is above
average.

.LONG TERM.../ Friday through Wednesday / The low to the southwest
of Haida Gwaii on Thursday will move south to rotate about a
second low off the Pacific Northwest Coast by late Thursday. High
pressure over Northwestern Canada will slowly weaken into the
weekend. As such the gusty northerly outflow winds over the
northern panhandle will diminish as the pressure gradient
decreases. A weak residual trough will extend northward from the
British Columbia coastal waters to along the coastal waters off of
Prince of Wales Island, while a weak ridge of higher pressure
continues over the Gulf of Alaska. Further west a low approaches
the western gulf Friday evening and then dives this low southward
into the pacific by early Sunday.

With the tighter gradients continuing into Friday, have bumped up
the winds especially for the northern Panhandle on Friday
tapering off into Saturday. Lynn Canal looks like it could be up
to max gales from the north, and this may areas of freezing
spray to continue into the long range forecast period.

Aloft and upper level trough will transition eastward mainly over
the southern AK Mainland and this will spread some clouds east
over the northern gulf and may even spin up a weak surface low in
the northern gulf. This will impact the panhandle from Sunday into
early next week. Until this trough moves through the area
Southeast Alaska should get a couple days of dry weather, with the
coldest days being Friday and Saturday. Look for low temperatures
on those days single digits to low teens in the northern
panhandle areas.

Potential advisories or strong wind headlines continuing into
Friday in the Lynn Canal area, and possibly locally for Juneau
from a lingering Taku mountain wave event. Confidence is average
for the mid to long range forecast.

&&

.AVIATION...Moderate turbulence (or worse) and wind shear expected
below the flight levels for most of Southeast Alaska through the
next 24 hours.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning from 11 PM this evening to 11 PM AKST Thursday
     for AKZ025.
     Strong Wind through late tonight for AKZ017-018.
MARINE...Heavy Freezing Spray Warning for PKZ012.
     Storm Warning for PKZ012-013-043.
     Gale Warning for PKZ021-022-031>034-041-042-051-053.
     Small Craft Advisory for PKZ011-035-036-052.

&&

Fritsch/Bezenek

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