Small Craft Advisory 9, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
600 AM AKST Thu Jan 5 2017

.SHORT TERM...Satellite imagery and surface analysis indicate a
short wave pushing SE across the panhandle with a weak low W of
Baranof Island drifting slowly SE this morning.

Fog that impacted SE AK yesterday has lifted and is now a stratus
layer over most of the central and southern panhandle. Some
light snow showers have been reported over the central and
southern panhandle this morning. Expect precip and clouds to
diminish from NW-SE as the offshore gradient begins to increase
in response to the low sliding SE.

Main challenge remains strength/timing of the developing outflow.
Gusty winds already being reported over the northern panhandle and
N Lynn canal and models remain in good agreement that winds will
continue to increase through the day and overnight. Winds will be
increasing out of the usual outflow areas as the shortwave draws
cold air into the southern Yukon. Expect gales to develop over
most of the central and northern inner channels this afternoon
and evening with small craft advisories further S. Strongest
winds will be out of interior passes and over Lynn Canal where
storm force winds are expected by this evening.

All ingredients in place for Taku winds to develop this evening
and overnight and upgraded high wind watch to a warning for
downtown Juneau and Douglas through the weekend. A critical level
develops Thursday night as lighter winds align parallel to the
Coast Mountains. Strong cold air advection will also help push air
down the mountains given greater density as well.

Minimal changes to forecast focused mainly on local effects for
winds and minor adjustments to temps, sky cover and PoP fields to
reflect current trends using mainly on NAM for updates.

.LONG TERM...High Winds with 60 to 80 mph gusts will continue
in Downtown Juneau, Thane, Douglas, and West Juneau through late
Saturday night. Ultra-tight gradients along the Coast Mountains
will continue deep into the weekend even as cold air advection
ceases and temperatures begin warming. The key to the wind
warning's sustenance will likely be how it develops Friday into
Friday night. Nonetheless confidence is particularly high with
this Taku event. Given the strong outflow evident by NAEFS 850mb
wind speed 4-6 standard deviations above normal, we elected to
hoist a high wind watch for AKZ018 mainly for Skagway but also the
Klondike Highway. Gradient orientation becomes most favorable here
Friday night into Saturday night, thus the watch instead of the
warning at this stage.

Looking elsewhere, we still believe there is high potential for
widespread windy conditions across the Panhandle. Due to the
southerly flow and mild conditions of the past two winters, we
have not seen such a signature of an event in at least three
years, perhaps longer. Other communities to watch are Wrangell,
Kake, Angoon, Gustavus, Hoonah, Metlakatla, Klawock, Point Baker,
Port Protection, Elfin Cove, and Excursion Inlet where unusually
cold gusty northeast winds could develop through the early
weekend.

The main short-wave drops to the southeast gulf Friday into
Saturday. Tinier but no less impactful short-wave features will
rotate around this main low center and likely enhance snow shower
activity Friday into Saturday. It is potential for advisory level
snowfall sometime during the early weekend before the parent low
draws southward and dry/cold/breezy conditions take over. Some
spot in the southern Panhandle may receive up to 2 to 4 inches
during this time period.

Looking beyond the weekend looks continued chilly and dry through
next week.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning from 3 AM Friday to 3 AM AKST Sunday for
     AKZ025.
     Strong Wind from this evening through late tonight for AKZ022.
     Strong Wind late tonight for AKZ019-020.
     High Wind Watch from Friday evening through late Saturday night
     for AKZ018.
     Strong Wind from noon AKST today through late tonight for AKZ018.
     Strong Wind from this evening through late tonight for AKZ017.
MARINE...Storm Warning for PKZ012-051.
     Gale Warning for PKZ011-013-022-031-043-052-053.
     Small Craft Advisory for PKZ021-032>034-041-042.
&&

BC/JWA

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