Storm Warning 47, NWS Juneau, AK

175 
FZAK67 PAJK 221318
OFFAJK

Offshore Waters Forecast
National Weather Service Juneau AK
418 AM AKST Tue Dec 22 2020

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.

PKZ398-230730-
418 AM AKST Tue Dec 22 2020
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
An approaching storm force front bumps a ridge of high pressure 
over the southern Inner Channels into BC this morning. The front 
then arrives in the northern gulf this morning, proceeds to the 
eastern gulf coast tonight, and clears the southern Inner Channels
Wed. A ridge of high pressure builds across the SE gulf Wed. 

$$

PKZ310-230730-
Gulf of Alaska North of 55 Degrees North and East of 144 Degrees
West-
418 AM AKST Tue Dec 22 2020

...STORM WARNING TODAY THROUGH TONIGHT...

.TODAY...SE wind 40 kt increasing to 50 kt in the afternoon. Seas
16 ft building to 24 ft in the afternoon. Rain.
.TONIGHT...S wind 50 kt becoming SW 35 kt late. Seas 28 ft. Rain
in the evening. 
.WED...SW wind 25 kt. Seas 21 ft. S swell. 
.WED NIGHT...SW wind 15 kt in the evening becoming variable
less than 15 kt. Seas 16 ft. SW swell. 
.THU...E wind 30 kt. Seas 14 ft. 
.FRI...W wind 30 kt. Seas 16 ft. 
.SAT...S wind 15 kt. Seas 11 ft. 

$$

441 
FZAK67 PAJK 230007
OFFAJK

Offshore Waters Forecast
National Weather Service Juneau AK
307 PM AKST Tue Dec 22 2020

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.

PKZ398-231815-
307 PM AKST Tue Dec 22 2020
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
A storm force front moves across the eastern gulf this evening, 
then into the panhandle overnight. The SELY high winds persist 
over the Southern Inner Channels into Wed followed by a wind shift
to the W-SW. High pressure briefly passes over the central 
panhandle late Wed night. Outlook. Low pressure approaches from 
the south Thu night with increasing NELY outflow winds. 

$$

PKZ310-231815-
Gulf of Alaska North of 55 Degrees North and East of 144 Degrees
West-
307 PM AKST Tue Dec 22 2020

...STORM WARNING THROUGH TONIGHT...

.TONIGHT...S wind 50 kt becoming SW 35 kt late. Seas 28 ft. Rain
in the evening. 
.WED...SW wind 25 kt. Seas 21 ft. S swell. 
.WED NIGHT...SW wind 15 kt in the evening becoming variable
less than 15 kt. Seas 16 ft. SW swell. 
.THU...SE wind 20 kt. Seas 13 ft. SW swell shifting to the W
in the afternoon. 
.THU NIGHT...E wind 25 kt. Seas 13 ft. SW swell. 
.FRI...W wind 25 kt. Seas 16 ft. 
.SAT...S wind 15 kt. Seas 11 ft. 
.SUN...S wind 15 kt. Seas 9 ft. 

$$

131 
FZAK67 PAJK 231313
OFFAJK

Offshore Waters Forecast
National Weather Service Juneau AK
413 AM AKST Wed Dec 23 2020

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.

PKZ398-240715-
413 AM AKST Wed Dec 23 2020
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
A storm force front moves inland over the inner channels today.
High pressure briefly passes over the central  panhandle late
tonight into Thursday. The next low pressure system approaches
from the south Thursday night into Friday.  

$$

PKZ310-240715-
Gulf of Alaska North of 55 Degrees North and East of 144 Degrees
West-
413 AM AKST Wed Dec 23 2020

.TODAY...SW wind 30 kt diminishing to 20 kt in the afternoon.
Seas 23 ft. 
.TONIGHT...SW wind 15 kt in the evening becoming variable less
than 15 kt. Seas 16 ft. S swell. 
.THU...SE wind 20 kt. Seas 13 ft. S swell shifting to the W
in the afternoon. 
.THU NIGHT...E wind 25 kt. Seas 12 ft building to 16 ft
late. S swell. 
.FRI...W wind 25 kt. Seas 15 ft. 
.SAT...S wind 15 kt. Seas 10 ft. 
.SUN...S wind 20 kt. Seas 9 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
217 PM AKST Mon Dec 21 2020

.SHORT TERM.../Monday night through Wednesday night/...Monday has
been a relatively calm day with light winds and mostly cloudy
skies in most areas with some isolated light convective showers
and isolated fog around the Panhandle.

This short-lived lull will quickly come to an end as a potent
storm-force frontal system moves toward southeast Alaska for the
Tuesday night through Wednesday night timeframe, bringing with it
heavy rain for the majority of the Panhandle and appreciable snow
amounts for the Haines and Klondike Highway areas. Model guidance
continues to show that there will be a deep layer of moisture
across the Panhandle with a deep layer of cold air for areas west
of Haines and north of Skagway, as well.

A Winter Storm Watch is in effect for inland areas on the
Klondike highway north of Skagway and the Haines Highway west of
Haines for 7 to 14 inches of snow from Tuesday afternoon through
Wednesday morning. This system is carrying with it a long fetch of
deep moisture originating from the central Pacific "Pineapple
Express" region aimed toward southeast Alaska. As forecast
soundings show, a deep layer of cold air, extending all the way to
the surface, will be in place for these areas to receive
significant and impactful snow amounts. Use extra caution and take
extra time if you must travel these highways Tuesday afternoon
through Wednesday morning. Prepare for limited visibility and
slippery roads.

For the rest of southeast Alaska, the primary form of
precipitation should remain rain as warm air advection as can be
seen at 850 mb in the models will be pushing into the central and
southern Panhandle ahead of the front, keeping temperatures
fairly steady in the middle 30s to lower 40s on average for most
places. As for the models, they are in pretty good agreement about
this scenario for the short- term forecast period. This is
another atmospheric river scenario for southeast Alaska with model
forecast Vertically Integrated Water Vapor Transport(IVT) values
of 700 to 800 kg/(ms) as the frontal system approaches the
Panhandle. Rainfall amounts of 1 to 2 inches can be expected
across the Panhandle with higher amounts possible in areas that
favor upsloping. Flooding is a concern.

The outside waters, inner channels, and the Panhandle will see
strong winds due to a tight pressure gradient between a strong
high in British Columbia and the approaching frontal system.
Mariners should exercise extra caution Tuesday into Wednesday if
they must venture out due to the high winds and waves. Operators
of more susceptible high profile vehicles should use extra
caution while driving in the gusty winds. These winds could blow
down trees and power lines. A High Wind Watch is in effect from
Tuesday evening into Wednesday morning for the Juneau/Douglas area
and Gulf coastal areas in the central and northern Panhandle
including Port alexander, Sitka, Elfin Cove, Pelican, and Yakutat.
As the front moves inland over the Panhandle, the associated low
will move inland over south-central Alaska and weaken.

Fog remains a possibility over some areas in the central and
southern Panhandle Monday evening into Tuesday morning due to
decreased cloudiness and calmer winds preventing convective mixing
and allowing for good radiational cooling to occur.

.LONG TERM.../ Wednesday to Monday as of 9 pm Sunday / Major
frontal feature finishes moving through Southeast Alaska
Wednesday, with a small feature running northward on the front as
it moves through the panhandle. A large broad area of low
pressure will slowly weaken over the Bering Sea. The good model
agreement in regards to the big front comes to a halt on
Wednesday. Thursday to into the weekend, the pattern over the
gulf looks much more confused a broad area of lower pressure that
is expected to persist. The various operational solutions have
difference in features, strengths, and locations moving through
the gulf during the weekend.

The Misty Fjords region will continue to keep snow falling as a
low level offshore cooler flow reinforcing the surface
temperatures. Will continue to watch the potential snow event for
the mid week.

There is one bit of minor agreement in the chaos for the last part
of the week, and that occurs Friday morning with a more developed
low moving northward just offshore of Haida Gwaii and the
panhandle. If that stays in the forecast, there could be a
significant system Christmas morning over the southern panhandle.
At the present, have there is a weaker version from WPC than the
operational solutions, that we can fine tune with future model
runs. Overall, think there will be moderate confidence on the
weather system for Friday, with lower than average confidence for
the weekend and start of the weekend.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Watch from Tuesday evening through Wednesday morning
     for AKZ025.
     High Wind Watch from Tuesday evening through late Tuesday night
     for AKZ017-022-023.
     Winter Storm Watch from Tuesday afternoon through Wednesday
     morning for AKZ018-019.
MARINE...Gale Warning for PKZ052.
     Small Craft Advisory for PKZ022-041>043-051-053.

&&

JLC/Bezenek

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