Small Craft Advisory 149, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
558 AM AKST Sat Mar 11 2017

.SHORT TERM...
The main weather driver across the Panhandle today is the front
approaching from the south. Ahead of the front, cold air remains
entrenched in the interior. The pressure gradient between interior
high pressure and the approaching front is driving gusty gap
winds across much of the central and northern Panhandle this
morning. This is supporting negative wind chills across portions
of the Klondike highway and northern PAnhandle this morning.
Models continue to indicate that conditions will be favorable
throughout the day today for Taku winds as the surface pressure
gradient increases along with cross barrier flow. In addition, the
upper level jet is still anticipated to slowly drift northwards
across the central Panhandle today, providing a supporting
critical layer at upper levels due to the wind direction reversal.

This morning it appears the front has a slightly slower
progression than previously indicated by models. As a result,
wind gusts are developing a few hours later than expected across
the Juneau area, but are generally showing an upward trend. In
addition, snowfall is expected to be delayed across the southern
Panhandle today, with mainly just a chance of snow throughout the
day and the steadier snow delayed until the later afternoon and
evening hours.

.LONG TERM...The overall pattern shift continues across Southeast
Alaska, as the trough extending southwest from the northern
panhandle to south of the Aleutians starts to become more north-
south oriented over the Gulf of Alaska through Monday and a result
the flow pattern over the panhandle and far eastern gulf. The
base of the upper level trough reaches 35 to 40 north Latitude, so
the access to warmer temperatures and increased water content for
atmosphere is increased. Through Sunday night while the surface
low moves north to be west and then northwest of Sitka Low level
warming will move the tight temperature gradient to the northern
panhandle to just north of the Icy Strait corridor. This may allow
snow to mix with rain as far north as Chichagof and northern
Admiralty Islands Sunday.

Northerly outflow event winding down across the northern panhandle
on Sunday though the Lynn Canal winds are not expected to relax
significantly until Monday.

Have maintained the present watches for snow accumulation from
Early Sunday into Sunday night. At the moment the situation
continues to loo promising, and will let the next shift get
another look to finalize the plans for the event.

Reviewed the extended forecast and refreshed some Precipitation
types overall but other wise little change to the the later stages
of the forecast. Forecast Confidence is Average to above average
into the early part of next week.

&&

.AVIATION...
Strong wind gusts are expected to continue across the Juneau area
into the evening hours. Generally VFR conditions are expected
today due to the downsloping.

&&

.MARINE...Gusty outflow winds are expected to continue throughout
much of the day today, as pressure gradients remain strong. Due to
cooler temperatures in place, heavy freezing spray is anticipated
in the morning hours and late evening hours across interior
channels. Areas of main concern include Z011, Z012, Z031, and
Z053.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Storm Watch from Sunday morning through Sunday evening
     for AKZ026.
     Winter Storm Watch from Sunday morning through Monday morning
     for AKZ024.
     High Wind Warning until 9 PM AKST this evening for AKZ025.
     Strong Wind from 9 AM AKST this morning through this evening for
     AKZ025.
     Winter Storm Watch from Sunday afternoon through Monday
     afternoon for AKZ025.
     Winter Storm Watch from Sunday morning through Sunday evening
     for AKZ023.
     Winter Storm Watch from Sunday afternoon through Monday morning
     for AKZ021.
     Winter Weather Advisory from 4 AM to 4 PM AKDT Sunday for AKZ028.
     Strong Wind until 3 PM AKST this afternoon for AKZ029.
     Winter Storm Watch from late tonight through Monday morning for
     AKZ029.
     Strong Wind from noon AKST today through late tonight for AKZ018.
     Wind Chill Advisory until 9 AM AKDT Sunday for AKZ018.
MARINE...Heavy Freezing Spray Warning for PKZ021-022-033>035.
     Heavy Freezing Spray Warning for PKZ013-053.
     Heavy Freezing Spray Warning for PKZ013-053.
     Heavy Freezing Spray Warning for PKZ011.
     Heavy Freezing Spray Warning for PKZ012-031.
     Gale Warning for PKZ012-013-022-031-033-051.
     Small Craft Advisory for PKZ011-021-032-034>036-041>043-053.
&&

EN/Bezenek

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