Storm Warning 68, NWS Anchorage, AK

024 
FZAK61 PAFC 072347
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
347 PM AKDT Tue Apr 7 2020

Offshore waters forecast for the Gulf of Alaska West of 144W

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

PKZ399-081400-
347 PM AKDT Tue Apr 7 2020
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 1002 mb low at 56N 152W Tue afternoon moves to 58N 148W Wed 
morning at 992 mb, then moves to 59N 142W at 1000 mb Wed afternoon. 
The low moves inland near 59N 139W Wed night. High pressure builds 
across the Gulf Thu afternoon.

$$

PKZ351-081400-
Gulf of Alaska Offshore North of 57N and West of 144W-
347 PM AKDT Tue Apr 7 2020

...STORM WARNING WEDNESDAY...

.TONIGHT...SE wind 25 to 40 kt becoming SW 20 to 35 kt after
midnight. Seas 10 to 14 ft. Rain and snow.
.WED...NW wind 30 to 50 kt. Seas 13 to 20 ft.
.WED NIGHT...NW wind 25 to 35 kt. Seas 10 to 16 ft.
.THU...NW wind 10 to 25 kt. Seas 7 to 11 ft.
.THU NIGHT...N wind up to 15 kt. Seas 4 to 7 ft.
.FRI THROUGH SUN...SE wind 10 to 25 kt. Seas 5 to 9 ft.

$$

PKZ352-081400-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
347 PM AKDT Tue Apr 7 2020

...STORM WARNING WEDNESDAY...

.TONIGHT...SW wind 25 to 40 kt. Seas 9 to 14 ft.
.WED...NW wind 30 to 50 kt diminishing to 20 to 35 kt in the 
afternoon. Seas 12 to 20 ft.
.WED NIGHT...NW wind 20 to 30 kt diminishing to 10 to 25 kt after
midnight. Seas 8 to 16 ft.
.THU...NW wind up to 20 kt. Seas 6 to 11 ft.
.THU NIGHT...NE wind up to 15 kt. Seas 5 to 8 ft.
.FRI THROUGH SUN...SW wind 10 to 25 kt. Seas 5 to 10 ft.

$$

321 
FZAK61 PAFC 081126
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
326 AM AKDT Wed Apr 8 2020

Offshore waters forecast for the Gulf of Alaska West of 144W

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

PKZ399-090230-
326 AM AKDT Wed Apr 8 2020
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 990 mb low at 59N 148W Wed morning moves inland near 59N 140W 
at 1001 mb by Wed afternoon. The associated front continues to 
weaken through Thu morning. High pressure builds across the 
Gulf Thu afternoon.

$$

PKZ351-090230-
Gulf of Alaska Offshore North of 57N and West of 144W-
326 AM AKDT Wed Apr 8 2020

...STORM WARNING TODAY...

.TODAY...W to NW wind 35 to 50 kt. Seas 11 to 17 ft.
.TONIGHT...W wind 25 to 35 kt. Seas 10 to 16 ft.
.THU...W wind 15 to 30 kt becoming NW 10 to 20 kt 
in the afternoon. Seas 7 to 12 ft.
.THU NIGHT...N wind up to 15 kt. Seas 4 to 7 ft.
.FRI THROUGH SUN...SE wind 15 to 30 kt. Seas 6 to 11 ft.

$$

PKZ352-090230-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
326 AM AKDT Wed Apr 8 2020

...STORM WARNING TODAY...

.TODAY...SW to NW wind 35 to 50 kt becoming W 25 to 35 kt 
in the afternoon. Seas 11 to 18 ft.
.TONIGHT...NW wind 15 to 30 kt. Seas 8 to 16 ft.
.THU...NW wind 10 to 20 kt. Seas 6 to 11 ft.
.THU NIGHT...NE wind up to 15 kt. Seas 5 to 8 ft.
.FRI THROUGH SAT...SE wind 15 to 30 kt. Seas 9 to 14 ft.
.SUN...S wind up to 15 kt. Seas 3 to 7 ft.

$$

633 
FZAK61 PAFC 082254
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
254 PM AKDT Wed Apr 8 2020

Offshore waters forecast for the Gulf of Alaska West of 144W

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

PKZ399-091300-
254 PM AKDT Wed Apr 8 2020
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 1000 mb low near 59N 142W Wed afternoon moves inland near 59N
139W at 1011 mb by Thu morning. High pressure builds across the 
Gulf through Fri afternoon.

$$

PKZ351-091300-
Gulf of Alaska Offshore North of 57N and West of 144W-
254 PM AKDT Wed Apr 8 2020

...GALE WARNING TONIGHT...

.TONIGHT...W wind 25 to 35 kt. Seas 10 to 16 ft.
.THU...NW wind 10 to 25 kt. Seas 7 to 12 ft.
.THU NIGHT...N wind 10 to 15 kt. Seas 4 to 7 ft.
.FRI...E wind up to 15 kt. Seas 5 ft.
.FRI NIGHT...E wind 10 to 25 kt. Seas 4 to 9 ft.
.SAT THROUGH MON...SE wind 15 to 30 kt. Seas 6 to 11 ft.

$$

PKZ352-091300-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
254 PM AKDT Wed Apr 8 2020

.TONIGHT...NW wind 15 to 30 kt. Seas 8 to 16 ft.
.THU...NW wind 10 to 20 kt. Seas 6 to 11 ft.
.THU NIGHT...NE wind 10 to 15 kt. Seas 5 to 8 ft.
.FRI...E wind 10 to 25 kt. Seas 6 ft.
.FRI NIGHT...E wind 15 to 30 kt. Seas 7 to 12 ft.
.SAT...SE wind 15 to 30 kt. Seas 9 to 14 ft.
.SUN THROUGH MON...SE wind up to 15 kt. Seas 3 to 7 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
458 PM AKDT Mon Apr 6 2020

.ANALYSIS AND UPPER LEVELS...
A strong, vertically-stacked low over the Interior continues to
dominate weather over much of the mainland. This low has been
responsible for the winds across much of Southcentral the past 36
hours. A strong upper level jet (300 mb 30,000') has offered
support flowing quickly from west to east at 150 kts. A "parting"
shortwave passed across the Susitna Valley down through the Kenai
Peninsula this morning. This feature brought the last, best surge
of winds. Overall, the winds should continue to diminish across
the area. Things are relatively quiet across the Bering with just
one smaller shortwave passing by the Pribilof Islands. This system
has some cold air behind it (850 mb -18C), so with steep lapse
rates, it will bring some heavy snow showers to the Pribilof
Islands and the eastern Bering. Another finger of the 300 mb jet
is pushing down the backside of this system at about 85 kts.

Finally, the main player associated with a developing storm system
can be seen on satellite. All of the moisture over the N Pacific
is slowly drifting NE towards the Gulf of AK. The shortwave over
the Bering (and its trailing cold air advection) will work in
tandem with this moisture to produce a strong system just east of
Kodiak Island on Tuesday.

&&

.MODEL DISCUSSION...
Models have struggled greatly with the upcoming storm in the Gulf
of AK. Yesterday, all models trended it further to the east and
left it to really only impact winds and waves across the Gulf.
Now, all models have trended significantly further to the west
with the low. The net effect will be the potential for heavy snow
and strong winds for Kodiak Island. This forecast package has
trended towards that solution and vastly increased QPF, winds, and
waves. However, we did not go 100% to any one solution as the
models continue to show signs of variability. All that said, there
is potential to bring in more significant weather to Kodiak and
the Gulf Coast if the evening model runs provide better clarity.

&&

.AVIATION...
PANC...VFR conditions will persist. SW winds will persist through
the daylight hours before they taper off later this evening.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Tonight
through Thursday)...

A few scattered snow showers along with gusty westerly winds will
persist through the evening hours before diminishing overnight as
the upper-level trough slides east. The lighter winds and
diminished cloud cover will allow overnight low temperatures to
drop into the teens across much of Southcentral, with some areas
of single digits within sheltered valleys and the Copper River
Basin. Cool and dry conditions continue across the Southcentral
mainland tomorrow as a ridge builds out ahead of an upper-level
shortwave sliding southeast across the AKPEN. This system will
induce the development of a potent north Pacific low that will
strength as it moves east of Kodiak Tuesday, with gales increasing
to storm-force winds along the north Gulf coast by late Tuesday
night into Wednesday morning.

While there is still a bit of uncertainty with the exact track of
this low, there has been better model consensus keeping the
center of circulation closer to the east coast of Kodiak Island.
This would yield stronger winds and heavier precipitation for the
island beginning Tuesday morning, continuing through the early
morning hours on Wednesday. It also looks like temperatures will
remain cold enough aloft and just cold enough near the surface for
this to be mainly a snow event, albeit a heavy, wet snow. Rain
may mix in at times along the immediate coast, but accumulating
snow is expected, with 5 to 10 inches possible. A Winter Storm
Watch is currently out for this event.

By late Tuesday, snow and gusty northerly winds will also develop
over Cordova, ahead of the storm-force front. The snow and blowing
snow is then expected to spread over Thompson pass and parts of
the southern Copper River Basin overnight Tuesday and linger into
Wednesday afternoon. With a storm track from east of Kodiak to
Yakutat, areas of Southcentral north and east of the Kenai and
Chugach Mountains should remain cool and dry, only having to
content with an increase in cloud cover. As the storm exits on the
region on Wednesday, offshore gap winds will once again
strengthen along the north Gulf coast and Prince William Sound.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tonight
through Thursday)...

The eastern periphery of a low centered east of the Pribilofs will
be moving into the Kuskokwim Delta and the Western Capes tonight.
This will cause snow showers to develop, but accumulations should
be limited to a few inches at most. During the day Tuesday, the
showers will shift southward, with the snow shower activity
shifting to around the coastal Bristol Bay area. Clouds will
persist over the area through Thursday. Another front will skirt
the Kuskokwim Delta on Thursday, bringing another round of snow
showers to the area. Temperatures through Thursday will remain
well below normal, with highs in the upper 20s and 30s, while lows
are in the single digits and teens.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Tonight
through Thursday)...

A small low centered just east of the Pribilofs is producing a
small area of gale force winds in the waters around and east of
the islands this afternoon. The models have finally come into
better agreement that the low will shift southward. The center of
the low will be near the Port Heiden area on Tuesday morning.
Thus, small craft to minimal gale force northerly winds will
continue on the Bering side of the Alaska Peninsula through
Tuesday. A second low will move across the northern Bering on
Tuesday, but it will be weak, and will dissipate on Wednesday.

A front and associated low will move into the western Aleutians
Tuesday afternoon and evening. It will gradually shear apart as it
moves into the central Bering, but a portion of the front will
persist into the northern Bering on Wednesday. The associated low
will track near the western and central Aleutians Wednesday night.

&&

.MARINE (Days 3 through 5)...(Thursday through Saturday)

Bering Sea/Aleutians…

A 998 mb low just south of the Rat Islands Thursday afternoon
will send an associated near gale force front into the west
central Aleutians. This front will reach the Alaska Peninsula by
Friday afternoon and looks to remain just under gale force. The
associated low moves into the northwest Bering as another low and
associated front approaches the western Aleutians from the North
Pacific.

Gulf of Alaska…

A strong area of high pressure centered over the Copper River Basin
will keep the Gulf dry with light winds for Thursday and Friday,
before a near gale force front approaches the southern Gulf on
Saturday.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Model guidance remains in good agreement on the upper level
pattern Friday into Saturday as an upper level ridge dominates
most of the mainland of Alaska. This will continue the theme of a
warming trend in temperatures with each day being warmer than the
previous. Overall, a warmer and dry pattern for the mainland.
Beyond Saturday, some differences are beginning to emerge that
weren’t quite evident in the models yesterday. Model guidance is
now hinting at a storm system over the North Pacific south of the
central Aleutians being drawn northward that may undercut the
ridge and bring a possible period of unsettled weather out there
for the second half of next weekend. Model guidance then really
spreads out beyond Sunday night of next weekend with the GFS
showing a more amplified ridge while the other model shows a
flatter weaker ridge moving in behind the aforementioned storm
system. An upper level trough is expected to be present over
eastern Russia and into the North Pacific Sunday night through
Monday showing a potential storm system moving northward. This may
bring a period of unsettled weather and increase in winds to the
Aleutian Chain and the Bering during this time. However, the exact
track and strength of this feature is still yet to be determined
with diminishing forecast confidence beyond Sunday.
&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch 171.
MARINE...Gale 131 132 138 179.
		 Storm 119 120.
 		 Heavy Freezing Spray 180-185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MSO
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JW
MARINE/LONG TERM...PD/MV