Heavy Freezing Spray Warning 155, NWS Anchorage, AK

706 
FZAK52 PAFC 162359
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
359 PM AKDT Fri Apr 16 2021

Coastal Waters Forecast for Southwest Alaska+Bristol Bay+The
Alaska Peninsula Waters and the Aleutian Islands up to 100 nm out.

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.

PKZ199-171300-
359 PM AKDT Fri Apr 16 2021
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

SEMISOPOCHNOI VOLCANO, 140 NM NORTHWEST OF ADAK IS CURRENTLY 
ACTIVE.

A 1004 mb low 325 nm northwest of Shemya moves 300 nm west of Saint
Matthew Island at 1023 mb Sun morning and dissipates. Its front 
moves eastward then stalls over the western to central Aleutians and 
central Bering through Sunday morning and weakens. A trough from the 
North Pacific enters the eastern Bering Sat night and drifts westward
through Pribilof Islands through Sun afternoon.

$$

PKZ150-171300-
South of the AK Peninsula Sitkinak to Castle Cape-
359 PM AKDT Fri Apr 16 2021

...SMALL CRAFT ADVISORY THROUGH SATURDAY NIGHT...

.TONIGHT...NE wind 25 kt. Seas 8 ft.
.SAT...E wind 25 kt. Seas 8 ft.
.SAT NIGHT...NE wind 25 kt. Seas 8 ft. Rain.
.SUN...NE wind 30 kt. Seas 10 ft.
.SUN NIGHT...NE wind 35 kt. Seas 12 ft.
.MON THROUGH WED...E wind 30 kt. Seas 13 ft.

$$

PKZ155-171300-
South of the AK Peninsula Castle Cape to Cape Sarichef-
359 PM AKDT Fri Apr 16 2021

...SMALL CRAFT ADVISORY SATURDAY NIGHT...

.TONIGHT...NE wind 20 kt. Seas 6 ft.
.SAT...NE wind 20 kt. Seas 5 ft.
.SAT NIGHT...N wind 20 kt except NE 25 kt from the Shumagin
Islands E. Seas 6 ft. Rain.
.SUN...NE wind 25 kt. Seas 6 ft.
.SUN NIGHT...NE wind 30 kt. Seas 11 ft.
.MON THROUGH WED...NE wind 30 kt. Seas 14 ft.

$$

PKZ160-171300-
Bristol Bay-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...NE wind 20 kt. Seas in ice free waters 4 ft.
.SAT...NE wind 20 kt. Seas in ice free waters 4 ft.
.SAT NIGHT...NE wind 15 kt. Seas in ice free waters 3 ft.
.SUN...NE wind 20 kt. Seas in ice free waters 4 ft.
.SUN NIGHT...NE wind 30 kt. Seas in ice free waters 6 ft.
.MON...NE wind 30 kt. Seas in ice free waters 6 ft.
.TUE THROUGH WED...NE wind 25 kt. Seas in ice free waters 4 ft.

$$

PKZ165-171300-
Port Heiden to Cape Sarichef-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...NE wind 15 kt. Seas 5 ft.
.SAT...NE wind 20 kt. Seas 5 ft.
.SAT NIGHT...NE wind 20 kt. Seas 5 ft.
.SUN...NE wind 20 kt. Seas 5 ft.
.SUN NIGHT...NE wind 30 kt. Seas 6 ft.
.MON THROUGH WED...NE wind 30 kt. Seas 10 ft.

$$

PKZ170-171300-
Cape Sarichef to Nikolski Bering Side-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...NE wind 15 kt. Seas 6 ft.
.SAT...Variable wind 10 kt. Seas 5 ft.
.SAT NIGHT...N wind 15 kt. Seas 4 ft.
.SUN AND SUN NIGHT...N wind 25 kt. Seas 7 ft.
.MON...NE wind 30 kt. Seas 10 ft.
.TUE THROUGH WED...NE wind 25 kt. Seas 11 ft.

$$

PKZ171-171300-
Unalaska Bay-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...NE wind 10 kt becoming variable less than 10 kt after
midnight. Seas 3 ft.
.SAT...Variable wind less than 10 kt becoming E 10 kt in the
afternoon. Seas 3 ft.
.SAT NIGHT...NE wind 10 kt becoming N after midnight. Seas 3 ft.
.SUN...N wind 15 kt. Seas 5 ft.
.SUN NIGHT...N wind 20 kt. Seas 7 ft.
.MON...NE wind 20 kt. Seas 7 ft.
.TUE...NE wind 15 kt. Seas 5 ft.
.WED...NE wind 20 kt. Seas 5 ft.

$$

PKZ172-171300-
Cape Sarichef to Nikolski Pacific Side-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...NE wind 15 kt. Seas 5 ft.
.SAT...NE wind 15 kt. Seas 5 ft.
.SAT NIGHT...N wind 20 kt. Seas 4 ft.
.SUN AND SUN NIGHT...N wind 25 kt. Seas 6 ft.
.MON...NE wind 25 kt. Seas 9 ft.
.TUE...NE wind 25 kt. Seas 13 ft.
.WED...NE wind 30 kt. Seas 14 ft.

$$

PKZ173-171300-
Nikolski to Seguam Island Bering Side-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...E wind 15 kt. Seas 5 ft.
.SAT...SE wind 15 kt. Seas 4 ft.
.SAT NIGHT...Variable wind 10 kt. Seas 3 ft.
.SUN AND SUN NIGHT...N wind 25 kt. Seas 7 ft.
.MON...N wind 30 kt. Seas 11 ft.
.TUE...N wind 20 kt. Seas 10 ft.
.WED...N wind 25 kt. Seas 11 ft.

$$

PKZ174-171300-
Nikolski to Seguam Island Pacific Side-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...Variable wind 10 kt. Seas 5 ft.
.SAT...SE wind 15 kt. Seas 4 ft.
.SAT NIGHT...Variable wind 10 kt. Seas 4 ft.
.SUN...N wind 25 kt. Seas 6 ft.
.SUN NIGHT...N wind 30 kt. Seas 9 ft.
.MON...N wind 30 kt. Seas 11 ft.
.TUE...N wind 20 kt. Seas 9 ft.
.WED...N wind 25 kt. Seas 11 ft.

$$

PKZ175-171300-
Seguam Island to Adak Bering Side-
359 PM AKDT Fri Apr 16 2021

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...SE wind 25 kt. Seas 7 ft.
.SAT...SE wind 20 kt. Seas 5 ft.
.SAT NIGHT...S wind 15 kt. Seas 6 ft.
.SUN...N wind 20 kt. Seas 7 ft.
.SUN NIGHT...N wind 25 kt. Seas 6 ft.
.MON...N wind 30 kt. Seas 10 ft.
.TUE...N wind 25 kt. Seas 10 ft.
.WED...N wind 20 kt. Seas 9 ft.

$$

PKZ176-171300-
Seguam Island to Adak Pacific Side-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...SE wind 20 kt. Seas 6 ft.
.SAT...SE wind 20 kt. Seas 7 ft.
.SAT NIGHT...SE wind 15 kt becoming variable wind less than 10 kt
after midnight. Seas 6 ft.
.SUN...N wind 15 kt. Seas 6 ft.
.SUN NIGHT...N wind 25 kt. Seas 6 ft.
.MON...N wind 30 kt. Seas 10 ft.
.TUE THROUGH WED...N wind 25 kt. Seas 8 ft.

$$

PKZ177-171300-
Adak to Kiska-
359 PM AKDT Fri Apr 16 2021

...GALE WARNING TONIGHT...

.TONIGHT...SE wind 35 kt. Seas 13 ft. Rain.
.SAT...W wind 30 kt becoming N wind in the afternoon. Seas 10 ft. 
Rain.
.SAT NIGHT...N wind 30 kt. Seas 11 ft.
.SUN...N wind 25 kt. Seas 8 ft.
.SUN NIGHT...N wind 20 kt. Seas 6 ft.
.MON...N wind 30 kt. Seas 7 ft.
.TUE...N wind 25 kt. Seas 8 ft.
.WED...N wind 20 kt. Seas 8 ft.

$$

PKZ178-171300-
Kiska to Attu-
359 PM AKDT Fri Apr 16 2021

...GALE WARNING TONIGHT...

.TONIGHT...W wind 35 kt. Seas 15 ft.
.SAT...NW wind 30 kt. Seas 14 ft.
.SAT NIGHT...NW wind 25 kt. Seas 10 ft.
.SUN...NW wind 20 kt. Seas 7 ft.
.SUN NIGHT...NW wind 15 kt. Seas 5 ft.
.MON...N wind 20 kt. Seas 4 ft.
.TUE...N wind 20 kt. Seas 8 ft.
.WED...NE wind 25 kt. Seas 8 ft.

$$

PKZ179-171300-
Pribilof Islands Near Shore Waters-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...SE wind 15 kt. Seas 5 ft.
.SAT...SE wind 15 kt. Seas 5 ft.
.SAT NIGHT...Variable wind 10 kt. Seas 4 ft.
.SUN...N wind 20 kt. Seas 6 ft.
.SUN NIGHT...N wind 25 kt. Seas 6 ft.
.MON...N wind 30 kt. Seas 8 ft.
.TUE THROUGH WED...NE wind 25 kt. Seas 9 ft.

$$

PKZ180-171300-
Kuskokwim Delta and Etolin Strait-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...NE wind 15 kt. Seas in ice free waters 3 ft.
.SAT...E wind 20 kt. Seas in ice free waters 4 ft.
.SAT NIGHT...NE wind 15 kt. Seas in ice free waters 4 ft.
.SUN...NE wind 20 kt. Seas in ice free waters 4 ft.
.SUN NIGHT...NE wind 25 kt. Seas in ice free waters 5 ft.
.MON...NE wind 25 kt. Seas in ice free waters 6 ft.
.TUE THROUGH WED...NE wind 30 kt. Seas in ice free waters 6 ft.

$$

PKZ181-171300-
North and West of Nunivak Island-
359 PM AKDT Fri Apr 16 2021

.TONIGHT...S wind 15 kt. Seas in ice free waters 3 ft.
.SAT...SE wind 15 kt. Seas in ice free waters 3 ft.
.SAT NIGHT...Variable wind 10 kt. Seas in ice free waters 3 ft.
.SUN AND SUN NIGHT...N wind 20 kt. Seas in ice free waters 4 ft.
.MON...N wind 30 kt. Seas in ice free waters 4 ft.
.TUE THROUGH WED...NE wind 20 kt. Seas in ice free waters 3 ft.

$$

PKZ185-171300-
Saint Matthew Island Waters-
359 PM AKDT Fri Apr 16 2021

...GALE WARNING TONIGHT...

.TONIGHT...S wind 25 kt E of Saint Matthew Island...S 35 kt W of
Saint Matthew Island. Seas in ice free waters 11 ft. 
.SAT...SE wind 20 kt E of Saint Matthew Island... S 30 kt W of
Saint Matthew Island. Seas in ice free waters 11 ft.
.SAT NIGHT...SE wind 15 kt E of Saint Matthew Island...S 25 kt W
of Saint Matthew Island. Seas in ice free waters 10 ft.
.SUN...SE wind 15 kt. Seas in ice free waters 7 ft.
.SUN NIGHT...NE wind 25 kt. Seas in ice free waters 6 ft.
.MON...N wind 30 kt. Seas in ice free waters 6 ft.
.TUE...NE wind 25 kt. Seas in ice free waters 6 ft.
.WED...NE wind 20 kt. Seas in ice free waters 6 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
431 PM AKDT Thu Apr 15 2021

.ANALYSIS AND UPPER LEVELS...
It's starting to look a bit like Spring in the pattern. First, a
building ridge of high pressure is taking shape over the Western
and Central Bering. Significantly warmer air aloft (5C at 850
mb/5000') is pushing in under this ridge. This warm air over the
colder water is helping to create some thick fog for the Western
Aleutians. On the leading edge of this ridge, gusty northerly
winds are pushing through parts of the Eastern Aleutians and the
Alaska Peninsula. This is clearly evidenced on satellite with some
impressive mountain waves to the south of the islands. Meanwhile,
a broad trough stretches from northern AK all the way down
through Kodiak Island to 40N in the Northern Pacific. A vertically
stacked upper level low is anchored within this trough. A few
weak waves of energy continue to rotate counter- clockwise around
the low and move into Southcentral and through Southwest AK. Most
of the precipitation associated with this is falling as rain along
coastal areas, but there are some snow showers in interior
portions of Southwest and the higher terrain of Southcentral.

The jet at 300 mb (30,000') is extremely amplified over the AOR.
It first climbs the ridge through Eastern Siberia at 135 kt. Then
it crests the ridge and dives south through the Alaska Peninsula
at 150 kt. It then turns underneath the trough in the Gulf of AK
before turning back north driving into Cordova at around 90 kt.
This is not atypical this time of year as warmer air starts to
push north over the Pacific and Lower 48 colliding with the cold
airmasses that have dominated the AK winter.

&&

.MODEL DISCUSSION...Models are in very good agreement lending to
high forecast confidence. The main issues will be dialing in some
of the details regarding the large diurnal temperature swings,
especially as it relates to any cloud cover. Fog may become an
issue as we go into the weekend with warmer air aloft trying to
nose in.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist. As a trough
approaches this evening, a few passing showers could move near the
terminal, but conditions are expected to remain VFR.

&&

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

A weak midlevel shortwave transiting the Kenai Peninsula from the
Gulf this evening will bring the last chance for rain and upper
elevation snow for the forecast period. Clearing skies on Friday
with ridging building in from the east will pave way for sunny
spring weather through the weekend. Some breezy winds are likely
over the eastern Prince William Sound on Saturday as a decent
pressure gradient sets up from the interior to the Gulf. Otherwise
the sunny weather and clear skies will lead to a high temperatures
raising a few degrees each day with 50s expected across most of
the region by Saturday. Due to remaining snow and radiational
cooling under clear skies overnight, morning lows will likely
hover at or below freezing. Kodiak Island will be the only area
with a slight chance of rain Friday and Saturday as a low transits
the north Pacific from east to west.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3...Tonight
through Sunday afternoon)...

Quiet and dry weather is expected for all of Southwest Alaska for
the forecast period. Northerly offshore flow across much of
Southwest is expected to continue through Friday evening before
turning southeasterly as the western side of an upper level ridge
to the east of the area moves overhead. As a result, expect mostly
clear to partly cloudy skies for the duration of the forecast
period. However, since the area is on the western edge of this
ridge especially the coastal areas of Bristol Bay and the
Kuskokwim Delta, an increase in cloud cover is possible Saturday
afternoon through the remainder of the forecast period with inland
locations remaining more sunny. Temperatures will warm each day
mainly 40s near the coast and 50s inland. Some parts of the Middle
Kuskokwim Valley may reach almost 60 degrees Sunday afternoon.
Overnight lows are expected to mainly be 20s for interior
locations and 30s along the coast. As a result of the warm
temperatures, rapid snowmelt is also expected.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Day 1 through
3...Tonight through Sunday afternoon)...

Northerly flow is expected to continue across the eastern Bering
through Friday evening. As a result, low stratus and occasional
rain/snow showers are expected from Nikolski east to Nelson Lagoon
through this evening before tapering off with just cloud cover
lingering. An upper level ridge will continue to build over the
western and central Bering bringing mostly quiet conditions with
some sunshine and low stratus in some areas. There is also some
areas of fog underneath this ridge around Shemya and the marine
waters around them. Areas of fog are expected from now through
Friday evening before the next system moves in.

A gale force frontal system will move into thew Western Aleutians
Islands overnight into Friday morning bringing unsettled weather
to Shemya and neighboring islands such as Attu Island. The frontal
system continues moving eastward though not making much progress
pass the west-central Bering where it will virtually stall out and
fizzle out as it hits up against the strong upper level ridge to
the east.

Lastly, multiple upper shortwaves rotating around an upper level
low to the south of the Aleutian Islands over the North Pacific
will bring periods of of unsettled weather from the southern
Alaska Peninsula west to around Nikolski for Saturday evening
and continuing through Sunday afternoon. An increase in winds is
also expected mostly small crafts mainly south of the Aleutian
Islands and Alaska Peninsula. The Pribilofs are also expected to
see some activity from these upper level shortwaves but not till
Sunday morning.

&&

.MARINE (Days 3 through 5: Sunday through Tuesday)...

Bering Sea/Aleutians:

The remnants of a frontal boundary will move across the Central
Bering Sea on Sunday. Winds are expected to remain below gale
force. A large dome of high pressure will build from the North
Pacific and in the eastern Bering.

Gulf of Alaska:

The back side of an upper level ridge will influence the Eastern
Gulf. A broad low pressure system will drift northwestward across
the Southern Gulf Sunday and Monday towards the North Pacific.

&&

.Long Term Forecast (Days 4 through 7: Monday through
Thursday)...

A "Rex Block" Pattern is expected during the extended forecast
period as a broad upper level low remains in place over the North
Pacific while a behemoth of an upper level ridge extends across
the Bering Sea and Alaska mainland. This pattern is expected for
the entirety of the forecast period. The models are pretty
consistent this forecast period. Due to the widespread subsidence
expect a warming trend for much of Mainland Alaska. A weak front
will approach the Gulf on Monday. The front will significantly
weaken before it reaches Southcentral, thus little to no
precipitation is expected. With the ridge building the low will
move northwestward over the North Pacific and away from
Southcentral.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 177 178 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MSO
SOUTHCENTRAL ALASKA...CJ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MV
MARINE/LONG TERM...PJS