Small Craft Advisory 687, NWS Anchorage, AK

Issued

Aug 31, 2021, 4:16 PM AKDT (00:16 UTC)

Expired

Aug 31, 2021, 5:30 PM AKDT

In force

74 min

Issued by

NWS Anchorage, AK

897 
FZAK52 PAFC 010016
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
416 PM AKDT Tue Aug 31 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.

PKZ199-010130-
416 PM AKDT Tue Aug 31 2021
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A 999 mb low 220 nm southwest of Saint Paul this afternoon will 
move over Bristol Bay at 996 mb Wednesday afternoon. The low then 
moves 275 nm northeast of Saint Paul at 998 mb Thursday 
afternoon.

$$

PKZ150-010130-
South of the AK Peninsula Sitkinak to Castle Cape-
416 PM AKDT Tue Aug 31 2021

...GALE WARNING TONIGHT...

.TONIGHT...NE wind 35 kt. Seas 9 ft. Rain.
.WED...NW wind 20 kt in the morning becoming variable 10 kt. Seas
7 ft.
.WED NIGHT...W wind 15 kt. Seas 5 ft.
.THU...SW wind 15 kt. Seas 6 ft.
.THU NIGHT...SW wind 20 kt. Seas 7 ft.
.FRI...SW wind 15 kt. Seas 6 ft.
.SAT THROUGH SUN...Variable wind 10 kt. Seas 4 ft.

$$

PKZ155-010130-
South of the AK Peninsula Castle Cape to Cape Sarichef-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...NE wind 10 kt except NE 20 kt from the Shumagin Islands 
E. Seas 6 ft.
.WED...Variable wind 10 kt. Seas 6 ft.
.WED NIGHT...W wind 15 kt. Seas 5 ft.
.THU AND THU NIGHT...W wind 20 kt. Seas 6 ft.
.FRI THROUGH SUN...NW wind 20 kt. Seas 6 ft.

$$

PKZ160-010130-
Bristol Bay-
416 PM AKDT Tue Aug 31 2021

...SMALL CRAFT ADVISORY WEDNESDAY...

.TONIGHT...E wind 20 kt. Seas 3 ft. Rain.
.WED...NE wind 25 kt. Seas 3 ft.
.WED NIGHT...N wind 10 kt. Seas 2 ft.
.THU...SW wind 15 kt. Seas 1 foot.
.THU NIGHT...SW wind 10 kt. Seas 1 foot.
.FRI THROUGH SAT...S wind 10 kt. Seas 2 ft.
.SUN...W wind 15 kt. Seas 5 ft.

$$

PKZ165-010130-
Port Heiden to Cape Sarichef-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...Variable wind 10 kt except E 20 kt from Port Moller E.
Seas 3 ft.
.WED...E wind 15 kt. Seas 3 ft.
.WED NIGHT...SW wind 15 kt except variable 10 kt from Port Moller
E. Seas 2 ft.
.THU AND THU NIGHT...W wind 20 kt. Seas 4 ft.
.FRI...W wind 20 kt. Seas 4 ft.
.SAT...W wind 15 kt. Seas 6 ft.
.SUN...NW wind 20 kt. Seas 6 ft.

$$

PKZ170-010130-
Cape Sarichef to Nikolski Bering Side-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...SE wind 15 kt. Seas 3 ft.
.WED...SW wind 15 kt. Seas 3 ft.
.WED NIGHT...W wind 20 kt. Seas 4 ft.
.THU AND THU NIGHT...W wind 20 kt. Seas 5 ft.
.FRI THROUGH SUN...NW wind 20 kt. Seas 5 ft.

$$

PKZ171-010130-
Unalaska Bay-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...SE wind 10 kt in the evening becoming variable less
than 10 kt. Seas 1 foot. Rain.
.WED...Variable wind less than 10 kt becoming W 15 kt in the
afternoon. Seas 2 ft. Rain.
.WED NIGHT...W wind 20 kt. Seas 3 ft.
.THU...W wind 20 kt. Seas 3 ft.
.THU NIGHT...W wind 15 kt. Seas 2 ft.
.FRI...W wind 15 kt. Seas 2 ft.
.SAT...W wind 10 kt. Seas 3 ft.
.SUN...NW wind 15 kt. Seas 5 ft.

$$

PKZ172-010130-
Cape Sarichef to Nikolski Pacific Side-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...SW wind 15 kt. Seas 4 ft.
.WED...W wind 20 kt. Seas 5 ft.
.WED NIGHT...W wind 20 kt. Seas 6 ft.
.THU...W wind 20 kt. Seas 6 ft.
.THU NIGHT...W wind 15 kt. Seas 5 ft.
.FRI THROUGH SUN...NW wind 20 kt. Seas 6 ft.

$$

PKZ173-010130-
Nikolski to Seguam Island Bering Side-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...W wind 15 kt. Seas 3 ft.
.WED...W wind 20 kt. Seas 4 ft.
.WED NIGHT...W wind 20 kt. Seas 4 ft.
.THU AND THU NIGHT...W wind 15 kt. Seas 4 ft.
.FRI THROUGH SUN...NW wind 20 kt. Seas 6 ft.

$$

PKZ174-010130-
Nikolski to Seguam Island Pacific Side-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...W wind 15 kt. Seas 5 ft.
.WED...W wind 20 kt. Seas 5 ft.
.WED NIGHT...W wind 20 kt. Seas 6 ft.
.THU...SW wind 20 kt. Seas 5 ft.
.THU NIGHT...W wind 15 kt. Seas 5 ft.
.FRI THROUGH SAT...W wind 20 kt. Seas 6 ft.
.SUN...NW wind 25 kt. Seas 6 ft.

$$

PKZ175-010130-
Seguam Island to Adak Bering Side-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...NW wind 15 kt. Seas 2 ft.
.WED...W wind 15 kt. Seas 4 ft.
.WED NIGHT...W wind 15 kt. Seas 4 ft.
.THU AND THU NIGHT...W wind 15 kt. Seas 3 ft.
.FRI THROUGH SUN...W wind 20 kt. Seas 5 ft.

$$

PKZ176-010130-
Seguam Island to Adak Pacific Side-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...NW wind 15 kt. Seas 4 ft.
.WED...W wind 15 kt. Seas 5 ft.
.WED NIGHT...W wind 15 kt. Seas 5 ft.
.THU AND THU NIGHT...W wind 15 kt. Seas 5 ft.
.FRI THROUGH SUN...NW wind 25 kt. Seas 6 ft.

$$

PKZ177-010130-
Adak to Kiska-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...NW wind 15 kt. Seas 4 ft.
.WED...W wind 15 kt. Seas 4 ft.
.WED NIGHT...W wind 15 kt. Seas 4 ft.
.THU AND THU NIGHT...W wind 20 kt. Seas 4 ft.
.FRI THROUGH SAT...W wind 25 kt. Seas 6 ft.
.SUN...W wind 20 kt. Seas 5 ft.

$$

PKZ178-010130-
Kiska to Attu-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...W wind 15 kt. Seas 4 ft.
.WED...W wind 15 kt. Seas 4 ft.
.WED NIGHT...NW wind 15 kt. Seas 3 ft.
.THU AND THU NIGHT...NW wind 20 kt. Seas 5 ft.
.FRI THROUGH SUN...SW wind 20 kt. Seas 6 ft.

$$

PKZ179-010130-
Pribilof Islands Near Shore Waters-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...SE wind 10 kt. Seas 3 ft.
.WED...NE wind 10 kt. Seas 3 ft.
.WED NIGHT...NE wind 15 kt. Seas 3 ft. Rain.
.THU...NE wind 15 kt. Seas 3 ft.
.THU NIGHT...NW wind 15 kt. Seas 3 ft.
.FRI THROUGH SUN...NW wind 20 kt. Seas 6 ft.

$$

PKZ180-010130-
Kuskokwim Delta and Etolin Strait-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...E wind 20 kt. Seas 4 ft.
.WED...E wind 20 kt. Seas 4 ft.
.WED NIGHT...NE wind 15 kt. Seas 3 ft.
.THU...NW wind 15 kt. Seas 3 ft.
.THU NIGHT...W wind 10 kt. Seas 2 ft.
.FRI THROUGH SUN...NW wind 20 kt. Seas 5 ft.

$$

PKZ181-010130-
North and West of Nunivak Island-
416 PM AKDT Tue Aug 31 2021

.TONIGHT...E wind 15 kt. Seas 4 ft.
.WED...NE wind 15 kt. Seas 3 ft.
.WED NIGHT...Variable wind 10 kt. Seas 2 ft.
.THU...N wind 15 kt. Seas 3 ft.
.THU NIGHT...N wind 20 kt. Seas 4 ft.
.FRI THROUGH SUN...NW wind 20 kt. Seas 5 ft.

$$

PKZ185-010130-
Saint Matthew Island Waters-
416 PM AKDT Tue Aug 31 2021

...SMALL CRAFT ADVISORY THROUGH WEDNESDAY...

.TONIGHT...E wind 20 kt E of Saint Matthew Island...NE 25 kt W of
Saint Matthew Island. Seas 6 ft. Rain.
.WED...E wind 15 kt E of Saint Matthew Island... NE 25 kt W of
Saint Matthew Island. Seas 5 ft.
.WED NIGHT...NE wind 15 kt. Seas 4 ft.
.THU...N wind 15 kt. Seas 3 ft.
.THU NIGHT...N wind 20 kt. Seas 4 ft.
.FRI THROUGH SUN...W wind 20 kt. Seas 6 ft.

$$

NWS Anchorage, AK wrote its last area forecast discussion before this small craft advisory went out at Aug 31, 5:34 AM AKDT, 10 hours 42 minutes earlier.

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
534 AM AKDT Tue Aug 31 2021

.ANALYSIS AND UPPER LEVELS...

A ridge of high pressure centered over the Gulf of Alaska is
gradually moving eastward. Upstream, a broad upper level trough is
in place over the Bering. This has allowed for clouds and showers
to persist across the Bering and the Aleutians. A frontal
boundary along the Southwest coast is producing rain showers that
are gradually lifting inland over Southwest. An organized low
centered south of the Alaska Peninsula is visible on satellite
imagery this morning and is gradually tracking northward. High
level clouds ahead of this low are beginning to lift inland and
spread over Southcentral.

&&

.MODEL DISCUSSION...

Models are in generally good agreement through the short term.
While there is better agreement with the track of the low moving
over Southcentral Wednesday, there are still some minor
differences, though confidence with this system is increasing.
The upper level energy associated with this low is distributed
differently between the NAM and GFS solutions, resulting in
slightly different low center placement on Wednesday morning. At
this time, the GFS has the low positioned west of Kodiak Island
while the NAM keeps the low centered east of Kodiak Island.
Despite these differences, the impacts of this storm remain the
same, and a NAM/GFS blend was preferred.

&&

.AVIATION...

PANC...VFR conditions and light winds are expected this morning. A
front approaching Southcentral this afternoon will produce
southeasterly Turnagain Arm winds late this afternoon into the
early evening. While winds are generally expected to remain over
Turnagain Arm and stay out of the terminal, there may be a brief
period of gusty southeasterly flow at the terminal during the
evening hours tonight.

&&

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

The high clouds encroaching on Southcentral this morning signal a
change in the pattern over the next few days. While most of the
region will continue to enjoy the influence of the ridge today,
an upper-level shortwave entering the western Gulf from the North
Pacific will begin to impact Kodiak Island. Models are beginning
to depict a more coherent picture of this and a second shortwave
entering the region through Thursday, allowing increased confidence
in the impacts these features will generate.

The first shortwave will provide sufficient support for an
intensifying surface low tracking northward into the Gulf, which
will produce widespread gale force winds and heavy rain across the
western Gulf and Kodiak Island beginning this afternoon and
evening. As the low tracks north, expect these conditions to reach
the southern Kenai Peninsula and southern Cook Inlet Wednesday
morning, with winds increasing quickly as a barrier jet sets up
along the coast. Wednesday evening, a second shortwave enters the
Gulf, helping to orient the front along the Gulf coast further
east, bringing heavy rain and strong winds into eastern Prince
William Sound late Wednesday. With a generally wrapped-up low
expected, the most significant rain and wind impacts are likely to
remain along the coastal regions through Thursday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Friday morning)...

A pattern shift is expected to occur over Southwest Alaska through
the end of the week. A broad upper trough is leading to a moist,
southerly upper flow downstream of its axis. As such, overcast
skies and scattered showers are seen along coastal areas in
Bristol Bay and the Kuskokwim Delta. This will continue through
the day. A low will approach Kodiak Island this evening. Light to
moderate rain will begin by early Wednesday morning beginning in
Bristol Bay and moving south to north through the day. The remnant
low will become vertically stacked and stall off the Kuskokwim
Delta coast and will continue to drive shower activity through
Friday.

&&

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

A broad upper trough and its associated surface low will slowly
track eastward across the central Bering/Aleutians through
Wednesday. Overcast skies and light rain will accompany it. The
low will then merge with a second weak low, becoming vertically
stacked and stall east of the Pribilofs. Thus, light showers will
persist over this area through Friday. A slightly colder weak
northerly flow will develop behind the low and although
precipitation will be less widespread, overcast skies will
continue.

&&

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

Bering/Aleutians...

Expect winds less than 35 kts and seas less than 20 ft for the
Day 3 through 5 period.

Gulf of Alaska...

Gale force winds are expected in the northern and western Gulf on
Thursday as low pressure moves across the area. Winds will then
ease late Thursday afternoon as the low weakens. Winds will then
remain below gale force on Friday and Saturday.

&&

.LONG TERM FORECAST (Days 3 through 7)...

The long term starts with a longwave trough encompassing all of
the Bering and Southwest Alaska, with an upper level low moving up
the Western Gulf of Alaska, which is helping to bring this trough
east. Longwave ridging continues to hold on over interior Alaska,
including the Copper River Basin. This ridge slides east over the
next couple of days and by the weekend our entire forecast area
is under a trough. This is very similar to what models had in the
forecast yesterday, so we can be confident in this pattern change.
This means expect a transition to active weather, with cooler and
cloudy conditions for many locations...as well as areas of
precipitation. The particulars of system placement will come in
the short term. The long range continues to show troughing over
all of Alaska into early next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storms...131.
         Gales...120, 130, 132, 137, 138, 139, 150, 351.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KO
SOUTHCENTRAL ALASKA...CQ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...ED/BB

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.