Small Craft Advisory 768, NWS Anchorage, AK

Issued

Sep 29, 2021, 2:24 PM AKDT (22:24 UTC)

Expired

Sep 30, 2021, 3:00 AM AKDT

In force

13 hr

Issued by

NWS Anchorage, AK

607 
FZAK52 PAFC 292224
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
Issued by National Weather Service Fairbanks AK
224 PM AKDT Wed Sep 29 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.

PKZ199-301100-
224 PM AKDT Wed Sep 29 2021
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A 972 mb low 200 NM NW of Saint Matthew Island will move to 400 NM N
of Atka as a 980 mb low by 4am Thu. By 4pm Thu, the low moves to 100
NM NW of Nikolski at 991 mb. An additional 1000 mb low will move to 
400 NM SE of Atka by 4pm Thu.

$$

PKZ150-301100-
South of the AK Peninsula Sitkinak to Castle Cape-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...SW wind 25 kt increasing to 35 kt after midnight. Seas
8 ft building to 13 ft after midnight. Rain showers.
.THU...W wind 45 kt. Seas 20 ft. Rain showers.
.THU NIGHT...W wind 30 kt diminishing to 20 kt after midnight.
Seas 15 ft subsiding to 10 ft after midnight.
.FRI AND FRI NIGHT...NW wind 35 kt. Seas 13 ft.
.SAT...NW wind 35 kt. Seas 14 ft.
.SUN...NW wind 30 kt. Seas 11 ft.
.MON...S wind 20 kt. Seas 8 ft.

$$

PKZ155-301100-
South of the AK Peninsula Castle Cape to Cape Sarichef-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...W wind 40 kt. Seas 17 ft. Rain showers.
.THU...W wind 40 kt. Seas 18 ft. Rain showers.
.THU NIGHT...NW wind 30 kt except W 25 kt from the Shumagin
Islands E. Seas 13 ft.
.FRI...NW wind 30 kt. Seas 12 ft.
.FRI NIGHT...NW wind 35 kt. Seas 13 ft.
.SAT...NW wind 35 kt. Seas 13 ft.
.SUN...W wind 30 kt. Seas 9 ft.
.MON...S wind 25 kt. Seas 16 ft.

$$

PKZ160-301100-
Bristol Bay-
224 PM AKDT Wed Sep 29 2021

...SMALL CRAFT ADVISORY THROUGH THURSDAY NIGHT...

.TONIGHT...SW wind 30 kt. Seas 9 ft. Rain showers.
.THU...W wind 30 kt. Seas 12 ft. Rain showers.
.THU NIGHT...W wind 25 kt. Seas 9 ft.
.FRI...NW wind 30 kt. Seas 10 ft.
.FRI NIGHT...NW wind 35 kt. Seas 12 ft.
.SAT...NW wind 35 kt. Seas 12 ft.
.SUN...NW wind 25 kt. Seas 8 ft.
.MON...SE wind 25 kt. Seas 6 ft.

$$

PKZ165-301100-
Port Heiden to Cape Sarichef-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...SW wind 35 kt becoming W 45 kt after midnight. Seas 14 ft
building to 20 ft after midnight. Rain showers.
.THU...W wind 45 kt diminishing to 30 kt in the afternoon. Seas
18 ft. Rain showers.
.THU NIGHT...NW wind 20 kt increasing to 30 kt after midnight.
Seas 15 ft.
.FRI...NW wind 30 kt. Seas 15 ft.
.FRI NIGHT...NW wind 35 kt. Seas 17 ft.
.SAT...NW wind 35 kt. Seas 15 ft.
.SUN...W wind 25 kt. Seas 9 ft.
.MON...S wind 30 kt. Seas 13 ft.

$$

PKZ170-301100-
Cape Sarichef to Nikolski Bering Side-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...W wind 40 kt. Seas 21 ft. Rain showers.
.THU...W wind 40 kt. Seas 21 ft. Rain showers.
.THU NIGHT...NW wind 30 kt. Seas 17 ft.
.FRI AND FRI NIGHT...NW wind 30 kt. Seas 15 ft.
.SAT...NW wind 30 kt. Seas 13 ft.
.SUN...SW wind 30 kt. Seas 10 ft.
.MON...S wind 30 kt. Seas 28 ft.

$$

PKZ171-301100-
Unalaska Bay-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...W wind 30 kt increasing to 40 kt after midnight. Seas
5 ft. Rain showers.
.THU...W wind 35 kt. Seas 5 ft. Rain showers.
.THU NIGHT...NW wind 30 kt. Seas 11 ft.
.FRI AND FRI NIGHT...NW wind 30 kt. Seas 11 ft.
.SAT...NW wind 25 kt. Seas 9 ft.
.SUN...SW wind 15 kt. Seas 2 ft.
.MON...S wind 25 kt. Seas 4 ft.

$$

PKZ172-301100-
Cape Sarichef to Nikolski Pacific Side-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...SW wind 40 kt. Seas 17 ft. Rain showers.
.THU...W wind 35 kt. Seas 14 ft.
.THU NIGHT...W wind 30 kt. Seas 12 ft.
.FRI AND FRI NIGHT...NW wind 30 kt. Seas 11 ft.
.SAT...NW wind 30 kt. Seas 10 ft.
.SUN...SW wind 25 kt. Seas 10 ft.
.MON...S wind 30 kt. Seas 26 ft.

$$

PKZ173-301100-
Nikolski to Seguam Island Bering Side-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY NIGHT...

.TONIGHT...W wind 35 kt. Seas 20 ft. Rain showers.
.THU...W wind 35 kt increasing to 45 kt in the afternoon. Seas
24 ft.
.THU NIGHT...N wind 35 kt diminishing to 25 kt after midnight.
Seas 21 ft.
.FRI AND FRI NIGHT...NW wind 25 kt. Seas 13 ft.
.SAT...W wind 20 kt. Seas 10 ft.
.SUN...S wind 30 kt. Seas 15 ft.
.MON...S wind 30 kt. Seas 34 ft.

$$

PKZ174-301100-
Nikolski to Seguam Island Pacific Side-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY NIGHT...

.TONIGHT...W wind 35 kt. Seas 16 ft. Rain.
.THU...W wind 30 kt increasing to 40 kt in the afternoon. Seas
16 ft.
.THU NIGHT...NW wind 40 kt becoming N 30 kt after midnight. Seas
19 ft.
.FRI AND FRI NIGHT...NW wind 25 kt. Seas 11 ft.
.SAT...NW wind 20 kt. Seas 9 ft.
.SUN...S wind 30 kt. Seas 16 ft.
.MON...SW wind 30 kt. Seas 31 ft.

$$

PKZ175-301100-
Seguam Island to Adak Bering Side-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...W wind 35 kt. Seas 18 ft.
.THU...W wind 40 kt. Seas 22 ft.
.THU NIGHT...N wind 30 kt diminishing to 20 kt after midnight.
Seas 20 ft subsiding to 14 ft after midnight.
.FRI AND FRI NIGHT...N wind 20 kt. Seas 11 ft.
.SAT...SW wind 15 kt. Seas 9 ft.
.SUN...S wind 30 kt. Seas 21 ft.
.MON...SW wind 35 kt. Seas 32 ft.

$$

PKZ176-301100-
Seguam Island to Adak Pacific Side-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY NIGHT...

.TONIGHT...W wind 35 kt becoming NW 25 kt after midnight. Seas
14 ft. Rain.
.THU...NW wind 25 kt increasing to 35 kt in the afternoon. Seas
12 ft.
.THU NIGHT...N wind 35 kt diminishing to 25 kt after midnight.
Seas 13 ft.
.FRI AND FRI NIGHT...N wind 20 kt. Seas 8 ft.
.SAT...SW wind 20 kt. Seas 7 ft.
.SUN...S wind 30 kt. Seas 25 ft.
.MON...SW wind 30 kt. Seas 30 ft.

$$

PKZ177-301100-
Adak to Kiska-
224 PM AKDT Wed Sep 29 2021

...SMALL CRAFT ADVISORY THROUGH THURSDAY NIGHT...

.TONIGHT...NW wind 30 kt. Seas 16 ft Bering side...12 ft Pacific 
side.
.THU...NW wind 30 kt. Seas 17 ft Bering side...11 ft Pacific side.
.THU NIGHT...N wind 25 kt. Seas 15 ft.
.FRI...N wind 15 kt. Seas 10 ft.
.FRI NIGHT...Variable wind 10 kt. Seas 7 ft.
.SAT...SE wind 25 kt. Seas 8 ft.
.SUN...S wind 35 kt. Seas 28 ft.
.MON...SW wind 40 kt. Seas 28 ft.

$$

PKZ178-301100-
Kiska to Attu-
224 PM AKDT Wed Sep 29 2021

...SMALL CRAFT ADVISORY THROUGH THURSDAY NIGHT...

.TONIGHT...N wind 25 kt. Seas 12 ft.
.THU...N wind 30 kt. Seas 13 ft.
.THU NIGHT...N wind 25 kt. Seas 12 ft.
.FRI...NE wind 15 kt. Seas 8 ft.
.FRI NIGHT...SE wind 15 kt. Seas 6 ft.
.SAT...SE wind 30 kt. Seas 9 ft.
.SUN...S wind 40 kt. Seas 26 ft.
.MON...SW wind 40 kt. Seas 26 ft.

$$

PKZ179-301100-
Pribilof Islands Near Shore Waters-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING TONIGHT...

.TONIGHT...W wind 40 kt. Seas 17 ft. Rain showers.
.THU...NW wind 30 kt. Seas 17 ft.
.THU NIGHT...N wind 30 kt. Seas 15 ft.
.FRI AND FRI NIGHT...NW wind 30 kt. Seas 13 ft.
.SAT...W wind 25 kt. Seas 10 ft.
.SUN...SW wind 30 kt. Seas 10 ft.
.MON...S wind 30 kt. Seas 22 ft.

$$

PKZ180-301100-
Kuskokwim Delta and Etolin Strait-
224 PM AKDT Wed Sep 29 2021

...SMALL CRAFT ADVISORY THROUGH THURSDAY NIGHT...

.TONIGHT...S wind 30 kt becoming W after midnight. Seas 10 ft. Rain showers.
.THU...W wind 30 kt. Seas 13 ft.
.THU NIGHT...N wind 30 kt. Seas 12 ft.
.FRI AND FRI NIGHT...NW wind 35 kt. Seas 14 ft.
.SAT...NW wind 30 kt. Seas 13 ft.
.SUN...W wind 25 kt. Seas 7 ft.
.MON...SE wind 30 kt. Seas 13 ft.

$$

PKZ181-301100-
North and West of Nunivak Island-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...S wind 35 kt becoming N after midnight. Seas 11 ft. Rain.
.THU...N wind 35 kt. Seas 14 ft. Rain.
.THU NIGHT...N wind 30 kt. Seas 14 ft.
.FRI AND FRI NIGHT...NW wind 35 kt. Seas 14 ft.
.SAT...NW wind 30 kt. Seas 10 ft.
.SUN...S wind 25 kt. Seas 6 ft.
.MON...SE wind 30 kt. Seas 13 ft.

$$

PKZ185-301100-
Saint Matthew Island Waters-
224 PM AKDT Wed Sep 29 2021

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...E of Saint Matthew Island, W wind 35 kt becoming NW 20 kt
after midnight. W of Saint Matthew Island, W wind 45 kt. Seas 24 ft.
.THU...N wind 40 kt diminishing to 30 kt in the afternoon. Seas 18 ft.
.THU NIGHT...N wind 30 kt. Seas 14 ft.
.FRI AND FRI NIGHT...NW wind 30 kt. Seas 12 ft.
.SAT...SW wind 25 kt. Seas 8 ft.
.SUN...S wind 30 kt. Seas 13 ft.
.MON...E wind 30 kt. Seas 20 ft.

$$

NWS Anchorage, AK wrote its last area forecast discussion before this small craft advisory went out at Sep 29, 5:30 AM AKDT, 8 hours 54 minutes earlier.

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
530 AM AKDT Wed Sep 29 2021

.ANALYSIS AND UPPER LEVELS...

The jet stream extends from eastern Siberia to the south of the
Aleutian Chain and into the southeastern Gulf of Alaska, with a
130+ cyclonically curved jet streak in the left exit region. Along
the jet, a potent shortwave trough and rapidly intensifying
surface low from the Kamchatka Peninsula is crossing the northern
Bering Sea. Small craft to gale force winds can be seen on the
ASCAT passes in response to a tightening pressure gradient with
this well developed system. Additionally, an upper level wave is
moving onshore over the Kuskowim Delta and Bristol Bay, bringing
light rain showers inland. Meanwhile, a vertically stacked low
over the Gulf continues to show signs of weakening as it
progresses east toward the AL-Can border. A band of rain showers
on the north side of this low is moving near the coastal areas of
Prince William Sound. The Nighttime Microphysics (RGB) this
morning shows mostly clear skies from the Mat-Su valleys into
Anchorage, and south toward the Kenai Peninsula. Clear skies and
strong radiational cooling is allowing overnight temperatures to
drop down below freezing across the lower elevation regions.

&&

.MODEL DISCUSSION...

Overall, the latest operational model runs are in decent agreement
with the synoptic scale features in the short term. Beyond that
time, however, models seem to struggle with the track of the
aforementioned Bering low with the center crossing either the
Aleutian Chain or southern AKPEN on Thursday afternoon. Moreover,
pieces of energy associated with the Bering low will play a role
in forming a triple point low in the western Gulf on Thursday as
well. Uncertainty starts to emerge with the track, position, and
interaction of this low with a North Pacific low heading toward
the southeastern Gulf on Friday evening. Subsequent models will be
needed to iron out specific details for better consistency and
increase forecast certainty with these systems. Suffice to say
that an active weather pattern will be underway in the week
ahead.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

There is a sharp delineation between clear skies from Kodiak
Northward through the Susitna Valley and clouds in Prince WIlliam
Sound stretching northward into the Copper River Basin. These
clouds are associated with a low in the Gulf which is elongating
and weakening through the day today. So far, rain has been
relegated to marine areas south of the Gulf coastline.

A front associated with a large Bering Sea low will move into the
western Gulf overnight with a triple point low developing along in
in northern Shelikof Strait Thursday morning. This low will track
eastward and bring rain to the north Gulf coast with snow at
higher elevations. What gets interesting with this low is the cold
air aloft ( around -35C at 500 mb) near the upper level low is
destabilizing the atmosphere that there could be some
thunderstorms develop in marine areas along the north Gulf coast
and possibly as far north as Prince William Sound on Thursday
night. Part of the reason is due to the relatively warm sea
surface temperatures this time of year which will enhance the
instability. Therefore any thunderstorms that develop will likely
remain over the water and the immediate coast.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

An elongated shortwave will continue to push across the Y-K Delta
this morning. Light showers were detected early this morning on
the Bethel radar (PABC) and these showers will move inland. Later
today a potent low over the Bering will intensify and a triple
point low will develop. Late Wednesday night another round of
moisture will get ushered into Western Alaska. Rainfall
amounts along the coast will range from 0.5 to 1 inch with this
front. Kuskokwim Mountains and Alaska Range will get a fresh
blanket of snow. By Thursday, the cold air advection may be strong
enough for Bethel to change over to snow.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

This morning there is a strong low between between NE Russia and
St. Matthew Island. This low is expected to deepen even more today
as it moves eastward. The low will pivot and dive southward across
the Central Bering and towards the Aleutians. The jet that is
steering this system doesn't even reach its peak until Thursday
and when its jet core position is south of the Aleutian chain.
This storm will produce a widespread area of strong winds and
rough seas. The models start to diverge with the track of the
surface low on Thursday. Continue to monitor the forecast for
updates along the Aleutians as new model data becomes available.

&&

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

A weakening low crosses the AKPen and eastern Aleutians into the
Gulf Friday morning. A swath of gales close to the center of the
low and south of the AKPen diminishes through the morning. Another
low near the Barren Islands produces a brief swath of gales south
of the Kenai Peninsula before diminishing through Friday morning.
Seas on the Pacific/Gulf side will remain below 20 ft with these
systems. A new low enters the Gulf from the North Pacific Friday
evening, with the potential to develop storm-force winds wrapping
the center and widespread gales Friday evening through Saturday
morning. Seas may reach 20 to 30 ft, particularly east of the low
center in the central or eastern Gulf, depending on low track.
Gusty gap winds approaching storm force off the AKPen and western
Gulf develop Friday night into Saturday morning. Winds diminish
and seas subside late Saturday into Sunday. Seas 20 to 30 ft are
possible as another low enters the western Bering on Sunday.
Widespread gales are likely through the western Aleutians and
western Bering through Sunday night with storm-force winds
possible concentrated near the low center.

.Long Term Discussion (Days 4 through 7: Saturday through Tuesday)...

A progressive amplified pattern is expected through Tuesday,
beginning with an upper-level trough situated over mainland
Alaska and the Gulf on Saturday. A shortwave at the base of this
trough supports the genesis of a potentially strong cyclone moving
northward in the Gulf early Saturday morning. Global models
continue to vary with the track of this system and solutions have
trended eastward today. As a result, impacts may be more limited
to the marine and coastal areas, with gap winds in the western
Gulf and precipitation along the north Gulf coast being the main
concerns. The EC and Canadian support this idea, being the
furthest east, and push the cyclone ashore near Yakutat with the
low rapidly weakening and the front moving inland quickly. The GFS
instead depicts a slower northward progression of the front and
hooks the low westward toward Prince William Sound, which would
produce more significant wind impacts along the coast and higher
potential for rain and snow inland over Southcentral. In either
case, with a closed upper-level low expected to remain over
Southcentral and the Gulf through Sunday, unsettled, cloudy
weather with chances for rain and snow flurries will remain
favored.

A strong shortwave ridge pushes eastward across the Bering ahead
of the extratropical remnants of Typhoon Mindulle entering the
western Bering on Sunday. High winds, up to storm-force, and rough
seas are expected with this low as it tracks into the central
Bering through Tuesday. Global models have been fairly consistent
with a minimum central pressure somewhere around the 950s in mb on
Monday over the western Bering. Ridging moves in over mainland
Alaska briefly on Monday before a front associated with the Bering
low moves ashore over Southwest Alaska and the AKPen, bringing
precipitation and windy conditions Monday night through Tuesday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storm Warning 185, 411-413
Gale Warning 130, 132, 139, 150, 155, 160, 165, 170-179, 181,
351-352, 414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MF
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PJS
MARINE/LONG TERM...CQ

Small Craft Advisories in Alaska, 2021Every small craft advisory in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text.