Gale Warning 5, NWS Juneau, AK

330 
FZAK67 PAJK 270023
OFFAJK

Offshore Waters Forecast
National Weather Service Juneau AK
323 PM AKST Fri Jan 26 2018

Offshore waters forecast for Gulf of Alaska east of 144W

Wind forecasts reflect the predominant speed and direction
expected. Sea forecasts represent the average of the highest
one-third of the combined windwave and swell height.

PKZ398-271830-
323 PM AKST Fri Jan 26 2018
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
A low pressure trough will remain over the eastern gulf through 
Fri night. A small low pressure area over the eastern gulf will 
move NW to the north central gulf by Fri evening. High pressure 
will build slowly over NW Canada through Sat night. 

$$

PKZ310-271830-
Gulf of Alaska North of 55 Degrees North and East of 144 Degrees
West-
323 PM AKST Fri Jan 26 2018

.TONIGHT...Wind variable less than 15 kt. Seas 7 ft. W swell. 
.SAT...E wind 15 kt. Seas 6 ft or less. W swell in the
morning. 
.SAT NIGHT...E wind 20 kt increasing to 30 kt late. Seas
6 ft or less then 7 ft late. 
.SUN...E gale to 35 kt. Seas 12 ft. Rain and snow in the
afternoon. 
.SUN NIGHT...E wind 30 kt. Seas 17 ft. Rain and snow in the
evening. 
.MON...NE wind 30 kt. Seas 18 ft. 
.TUE...S wind 20 kt. Seas 11 ft. 
.WED...SE wind 15 kt. Seas 8 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
251 PM AKST Thu Jan 25 2018

.SHORT TERM.../ Thu night to Saturday night / The quasi stationary
trough of lower pressure extending from near Prince William Sound
to west of Haida Gwaii persists with a low near Prince William
sound and a second west of Haida Gwaii. The southern of the lows
will be moving northwest along the trough through Friday afternoon
as it moves past Middleton Island. The trough will be weakening
or more correctly will be absorbed into the low forming over the
western gulf Friday and Friday night by a short wave moving into
the western gulf. High pressure over NW Canada and northern
Alaska will be increasing as the high strengthens.

Strong winds will continue over the northern Lynn Canal region and
mainly in Skagway area with winds reacting to the strong pressure
gradient over White Pass. Sustained winds 25 to 30 mph in Skagway
with gusts of 40 to 50 mph (or slightly) higher are expected into
Saturday night. Through Saturday and Saturday evening, the high
pressure is building more into northern British Columbia, this
combined with a trough moving northward over the southern
panhandle will be increasing the cross barrier easterly flow
especially in the Juneau area. We will be on the watch for the
potential start of a Taku mountain wave wind event later Saturday.

Precipitation-wise a collection of impulses will be moving
Northwest along the trough and spreading some light precipitation
into the southern panhandle and this will slowly work its way
northward to Glacier Bay and Juneau area by early Saturday. During
Saturday over the northeast pacific another low will be
developing and lifting northeast toward the southern panhandle and
British Columbia coast and this will be the next more significant
weather maker for Southeast Alaska.

.LONG TERM...As has been the case most of this winter, anomalous
high latitude blocking regime will be driving the weather pattern
over much of the state through the long term. Highly amplified
ridging over the Bering Sea at the start of the period will
begin to morph into an omega block by late in the weekend.
Subsequent downstream deep trough and associated closed mid/upper
low will continue to dig well south through the western Gulf and
into the NPAC by Saturday before a significant piece of this
energy ejects NE'ward into the SE Gulf by late Sunday and early
Monday.

At the surface, a very cold airmass will continue over the Gulf
underneath the upper trough on Saturday while cold continental
high pressure begins to build over NW Canada. This will set the
stage for continued outflow over the Panhandle through the weekend
with the potential for a more significant precipitation event
sometime late Sunday into Monday. The weekend should be mostly dry
with clearing skies likely by late Saturday especially over the
north. Initial pressure gradient will be more NE'ly so expect
places such as Cross Sound and Skagway to be windier than might be
expected for the strength of the gradient. As the surface high
builds over NW Canada and surface low pressure begins to approach
the SE Gulf on Sunday, expect the northerly gradient to increase
substantially with strong N'ly outflow likely to develop. It will
be quite cold, especially over the north where 925 mb temps bottom
out around -18C by Sunday.

Ensembles and operational models all indicate a significant
shortwave will eject out of the main upper trough towards SE AK on
Sunday night. This could set up potentially a significant
overrunning precip event early next week. Models differ in the
timing and strength of the system but all indicate precipitation
beginning over at least the southern Panhandle by late Sunday
evening. Thicknesses would support snow even for the south.
Differences increase in regards to the eventual northward extent
of precip at this time so kept highest chances south of Frederick
Sound for now. For the remainder of the forecast period, major
differences begin to develop in regards to the interaction of a
strengthening Pacific jet over the NPAC and the next piece of
strong arctic energy diving south around the blocking high. Leaned
towards WPC guidance for Monday through Thursday for this reason.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind through Saturday afternoon for AKZ018.
MARINE...Gale Warning for PKZ012-013-022-031-034-041>043-051-052.
     Small Craft Advisory for PKZ021-032-033-035-036.

&&

Bezenek/DEL

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