Small Craft Advisory 657, NWS Anchorage, AK

097 
FZAK51 PAFC 211149
CWFAER

Coastal Waters Forecast
National Weather Service Anchorage Alaska
349 AM AKDT Sat Aug 21 2021

Coastal Waters Forecast for the Northern Gulf of Alaska Coast
up to 100 nm out including Kodiak Island and Cook Inlet.

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.

PKZ197-220045-
349 AM AKDT Sat Aug 21 2021
.SYNOPSIS FOR THE NORTH GULF COAST+KODIAK ISLAND WATERS+
COOK INLET...

A ridge builds across the Gulf of Alaska through Sunday afternoon.
A front enters the western Gulf Sun morning. A 1006 mb low forms
along this front 40 nm west of Kodiak City Sun evening and 
continues to 70 nm east of Kodiak City at 1005 mb Sun night.

$$

PKZ119-220045-
Cape Suckling to Cape Cleare-
349 AM AKDT Sat Aug 21 2021

.TODAY...NW wind 20 kt. Gusts to 35 kt out of the Copper River Delta
this morning. Seas 6 ft.
.TONIGHT...W wind 20 kt diminishing to 10 kt after midnight. Seas 4 ft.
.SUN...Variable wind 10 kt. Seas 4 ft.
.SUN NIGHT...E wind 20 kt. Seas 6 ft.
.MON...E wind 30 kt. Seas 8 ft.
.TUE...E wind 25 kt. Seas 6 ft.
.WED...E wind 15 kt. Seas 5 ft.

$$

PKZ120-220045-
Cape Cleare to Gore Point-
349 AM AKDT Sat Aug 21 2021

.TODAY...NW wind 15 kt. Seas 5 ft.
.TONIGHT...W wind 15 kt. Seas 4 ft.
.SUN...Variable wind less than 10 kt becoming E 15 kt in the
afternoon. Seas 3 ft. Rain.
.SUN NIGHT...E wind 30 kt. Seas 6 ft.
.MON...NE wind 30 kt. Seas 8 ft.
.TUE...NE wind 20 kt. Seas 6 ft.
.WED...NE wind 15 kt. Seas 4 ft.

$$

PKZ121-220045-
Resurrection Bay-
349 AM AKDT Sat Aug 21 2021

.TODAY...N wind 20 kt diminishing to 10 kt in the afternoon. Seas 4 
ft subsiding to 2 ft in the afternoon.
.TONIGHT...Variable wind 10 kt becoming N after midnight. Seas 2 ft.
.SUN...N wind 10 kt becoming S 15 kt in the afternoon. Seas 3 ft. Rain.
.SUN NIGHT...N wind 15 kt. Seas 3 ft.
.MON THROUGH TUE...N wind 15 kt. Seas 3 ft.
.WED...N wind 10 kt. Seas 2 ft.

$$

PKZ125-220045-
Prince William Sound-
349 AM AKDT Sat Aug 21 2021

.TODAY...NW wind 15 kt. Seas 3 ft.
.TONIGHT...W wind 10 kt. Seas 2 ft.
.SUN...Variable wind less than 10 kt. Seas 2 ft.
.SUN NIGHT...NE wind 10 kt. Seas 2 ft.
.MON...NE wind 20 kt. Seas 3 ft.
.TUE...NE wind 15 kt. Seas 3 ft.
.WED...E wind 10 kt. Seas 2 ft.

$$

PKZ126-220045-
Port Valdez-
349 AM AKDT Sat Aug 21 2021

.TODAY...E wind increasing to 10 kt. Gusts to 20 kt near Valdez in 
the morning. Seas 2 ft.
.TONIGHT...E wind 10 kt. Seas 2 ft.
.SUN...E wind 10 kt in the morning becoming variable less than
10 kt. Seas 2 ft.
.SUN NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.MON THROUGH TUE...E wind 10 kt. Seas 2 ft.
.WED...SW wind 10 kt. Seas 2 ft.

$$

PKZ127-220045-
Valdez Narrows-
349 AM AKDT Sat Aug 21 2021

...SMALL CRAFT ADVISORY TODAY...

.TODAY...NE wind increasing to 25 kt this morning...then diminishing
to 15 kt in the afternoon. Seas 3 ft.
.TONIGHT...NE wind 15 kt. Seas 3 ft.
.SUN...NE wind 15 kt becoming SW 10 kt in the afternoon. Seas 3 ft.
.SUN NIGHT...NE wind 10 kt. Seas 2 ft.
.MON THROUGH TUE...NE wind 20 kt. Seas 3 ft.
.WED...Variable wind 10 kt. Seas 2 ft.

$$

PKZ128-220045-
Valdez Arm-
349 AM AKDT Sat Aug 21 2021

.TODAY...NE wind increasing to 20 kt this morning...then diminishing
to 10 kt in the afternoon. Seas 4 ft.
.TONIGHT...NE wind 10 kt. Seas 2 ft.
.SUN...NE wind 10 kt in the morning becoming variable less than
10 kt. Seas 2 ft.
.SUN NIGHT...NE wind 10 kt. Seas 2 ft.
.MON THROUGH TUE...NE wind 15 kt. Seas 3 ft.
.WED...NE wind 10 kt. Seas 2 ft.

$$

PKZ129-220045-
Passage Canal-
349 AM AKDT Sat Aug 21 2021

.TODAY...W wind 20 kt diminishing to 10 kt in the afternoon. Gusts 
to 30 kt near Whittier this morning. Seas 3 ft.
.TONIGHT...W wind 10 kt. Seas 2 ft.
.SUN...E wind 10 kt. Seas 2 ft. Rain.
.SUN NIGHT...E wind 15 kt. Seas 2 ft.
.MON...E wind 15 kt. Seas 2 ft.
.TUE THROUGH WED...E wind 10 kt. Seas 2 ft.

$$

PKZ130-220045-
West of Barren Islands including Kamishak Bay-
349 AM AKDT Sat Aug 21 2021

...SMALL CRAFT ADVISORY TODAY AND SUNDAY...

.TODAY...W wind 25 kt in the morning becoming variable 10 kt. Seas
7 ft subsiding to 2 ft in the afternoon.
.TONIGHT...Variable wind 10 kt. Seas 2 ft.
.SUN...E wind 15 kt increasing to 25 kt in the afternoon. Seas 3
ft building to 8 ft in the afternoon. Rain.
.SUN NIGHT...NE wind 30 kt. Seas 9 ft.
.MON...NE wind 15 kt. Seas 5 ft.
.TUE...Variable wind 10 kt. Seas 3 ft.
.WED...Variable wind 10 kt. Seas 2 ft.

$$

PKZ131-220045-
Barren Islands East-
349 AM AKDT Sat Aug 21 2021

...SMALL CRAFT ADVISORY TODAY AND SUNDAY...

.TODAY...NW wind 25 kt. Seas 7 ft subsiding to 4 ft in the afternoon.
.TONIGHT...SW wind 20 kt in the evening becoming variable 10 kt.
Seas 4 ft.
.SUN...SE wind 15 kt becoming E 25 kt in the afternoon. Seas 4 ft. Rain.
.SUN NIGHT...E wind 35 kt. Seas 7 ft.
.MON...NE wind 30 kt. Seas 8 ft.
.TUE...NE wind 15 kt. Seas 7 ft.
.WED...NE wind 15 kt. Seas 4 ft.

$$

PKZ132-220045-
Marmot Island to Sitkinak-
349 AM AKDT Sat Aug 21 2021

.TODAY...SW wind 15 kt. Seas 5 ft.
.TONIGHT...S wind 15 kt. Seas 3 ft.
.SUN...S wind 20 kt. Seas 5 ft. Rain.
.SUN NIGHT...SW wind 20 kt. Seas 5 ft.
.MON...W wind 20 kt. Seas 8 ft.
.TUE THROUGH WED...W wind 15 kt. Seas 5 ft.

$$

PKZ136-220045-
Chiniak Bay-
349 AM AKDT Sat Aug 21 2021

.TODAY...Variable wind less than 10 kt. Seas 3 ft.
.TONIGHT...Variable wind less than 10 kt. Seas 2 ft.
.SUN...SE wind 10 kt increasing to 15 kt in the afternoon. Seas
3 ft. Widespread rain showers.
.SUN NIGHT...NE wind 15 kt. Seas 3 ft.
.MON...NW wind 10 kt. Seas 3 ft.
.TUE...Variable wind less than 10 kt. Seas 2 ft.
.WED...Variable wind less than 10 kt. Seas 2 ft.

$$

PKZ137-220045-
Marmot Bay-
349 AM AKDT Sat Aug 21 2021

.TODAY...W wind 10 kt in the morning becoming variable less than
10 kt. Seas 2 ft.
.TONIGHT...Variable wind less than 10 kt. Seas 3 ft.
.SUN...E wind 10 kt increasing to 15 kt in the afternoon. Seas 4
ft. Rain.
.SUN NIGHT...E wind 15 kt. Seas 4 ft.
.MON...NW wind 15 kt. Seas 3 ft.
.TUE...N wind 10 kt. Seas 3 ft.
.WED...Variable wind less than 10 kt. Seas 3 ft.

$$

PKZ138-220045-
Shelikof Strait-
349 AM AKDT Sat Aug 21 2021

.TODAY...SW wind 15 kt. Seas 3 ft.
.TONIGHT...Variable wind 10 kt. Seas 3 ft.
.SUN...NE wind 20 kt. Seas 5 ft. Widespread rain showers.
.SUN NIGHT...NE wind 20 kt. Seas 7 ft.
.MON THROUGH TUE...NE wind 15 kt. Seas 4 ft.
.WED...Variable wind 10 kt. Seas 2 ft.

$$

PKZ139-220045-
Cook Inlet Kalgin Island to Point Bede-
349 AM AKDT Sat Aug 21 2021

.TODAY...N wind 10 kt. Seas 2 ft.
.TONIGHT...Variable wind less than 10 kt. Seas 2 ft.
.SUN...NE wind 10 kt. Seas 3 ft. Rain.
.SUN NIGHT...N wind 20 kt. Seas 6 ft.
.MON...N wind 15 kt. Seas 5 ft.
.TUE...N wind 10 kt. Seas 3 ft.
.WED...SW wind 15 kt. Seas 3 ft.

$$

PKZ140-220045-
Cook Inlet North of Kalgin Island-
349 AM AKDT Sat Aug 21 2021

.TODAY...N wind 10 kt in the morning becoming variable less than
10 kt. Seas 2 ft.
.TONIGHT...Variable wind less than 10 kt. Seas 2 ft.
.SUN...NE wind 10 kt. Seas 2 ft.
.SUN NIGHT...NE wind 15 kt. Seas 4 ft.
.MON...NE wind 15 kt. Seas 4 ft.
.TUE...N wind 10 kt. Seas 3 ft.
.WED...S wind 10 kt. Seas 3 ft.

$$

PKZ141-220045-
Kachemak Bay-
349 AM AKDT Sat Aug 21 2021

.TODAY...Variable wind less than 10 kt becoming SW 10 kt in the
afternoon. Seas 2 ft.
.TONIGHT...SW wind 10 kt in the evening becoming variable less
than 10 kt. Seas 2 ft.
.SUN...Variable wind less than 10 kt. Seas 2 ft. Rain.
.SUN NIGHT...NE wind 10 kt. Seas 2 ft.
.MON...Variable wind less than 10 kt. Seas 2 ft.
.TUE...NE wind 10 kt. Seas 2 ft.
.WED...Variable wind less than 10 kt. Seas 2 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
521 AM AKDT Fri Aug 20 2021

.ANALYSIS AND UPPER LEVELS...

A closed upper level low is currently located east of Nome, Alaska
this morning embedded in the longwave trough moving across the
state. Another upper level low is currently spinning in the North
Pacific south of Adak along the Central Aleutian Island Chain. The
aforementioned closed upper level low has a corresponding weak
surface low just to its southeast. Looking at nighttime
microphysics imagery this morning, you can see the comma head
shape to the storm system currently moving across the state. This
resembles the storm in its mature phase. At the surface, a cold
front with a line of heavy rain was seeing moving eastward from
Fairbanks south through the Susitna Valley down to Homer. Areas of
the Susitna Valley and the Matanuska Valley are seeing the
heaviest rainfall amounts from this system as the core of the
upper level energy is moving through this area providing the best
lift in the atmosphere. Clouds were seen lowering and thickening
across the Copper River Basin as the front continues moving east
this morning.

On the backside of the system, some clearing was seen taking place
across Southwest Alaska. This was especially evident downstream of
the Kuskokwim/Kilbuck Mountains as the westerly flow across the
mountains downslope out on the east side. Some pockets of clear
sky are also evident across the Kuskokwim Delta, though, with a
westerly flow and better marine influence from the Bering, the
clearing isn't as much.

Lastly, ASCAT Scatterometer data around 20/09z was showing small
craft advisory winds occurring across the marine waters south of
the Central Aleutian Chain this morning as a low pressure system
spins to the south of the area. This low is only slowly meandering
about in this area, therefore, prolonged unsettled conditions are
expected this morning.

&&

.MODEL DISCUSSION...

Model guidance is overall in good agreement on the synoptic scale
features out through Day 3. All guidance is handling the current
longwave trough moving across the interior part of the state well.
Guidance is also in good agreement on a compact closed upper level
low situated just to the west of the Bering Sea and another closed
upper level low to the southeast of Dutch Harbor through Saturday
night.
Beyond Saturday night is when the models begin to diverge on
these two features. The NAM and GFS are consistent with each other
out through Sun night keeping the two closed upper level lows
separate from one another with no interaction. They both keep one
near Attu Island and the other one moving just south of the Gulf
of Alaska by Saturday night. The EC and Canadian-NH on the other
hand try to stretch out some of the energy with the upper level
low near the Western Aleutians and phase some of it with the other
upper level lows energy south of Dutch Harbor Sunday/Sunday night
time frame. As a result, this will impact exactly where this
feature south of Dutch Harbor goes as more interaction will help
to pull it northward towards the Alaska Peninsula whereas less
interaction (remaining separate) will cause it to continue moving
northeastward skirting the southern portion of the Gulf of Alaska.

&&

.AVIATION...

PANC...MVFR conditions are currently being observed at the
terminal. This is expected to continue through around 15z this
morning before lifting back to VFR conditions around 4000 ft. Winds
from Turnagain Arm are peaking now and are expected to continue
through mid-late morning hours before diminishing. There is
expected to be an end to the rain around 14-15z this morning with
dry conditions expected through around noon with the chance for
showers returning between 20/20z and 21/03z this evening. After
21/03z this evening, VFR conditions and light winds will persist
through the end of the TAF package.

&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2:
Today through Sunday morning)...

A potent upper-level wave and associated cold front is moving
quickly across Southcentral this morning. This system brought a
quick shot of moderate to heavy rain from Kenai up to Talkeetna,
with anywhere from one tenth to two thirds of an inch of rain
fell. So far, the highest totals have occurred across the
Matanuska Valley. The strong southwesterly winds across Cook
Inlet and the Anchorage Bowl this morning will slowly taper off as
the upper- level trough and surface low over the interior move
over the eastern half of the state.

A second wave will undercut the main upper-level trough and move
over Southcentral from the northwest later this morning. This
feature will not only allow showers to linger across parts of
Southcentral through the afternoon hours, but help to strengthen
the northwesterly flow aloft. As the entire trough slides east
this evening and a ridge builds over Southwest Alaska, northerly
and westerly gap winds will quickly increase for places like
Seward, Whittier, and Valdez as a more autumn-like pattern sets
up. The gradient looks strongest Friday evening through Saturday
morning, with gusts of 30 to 40 mph possible for Seward and
Whittier Saturday morning, with slightly weaker gusts for Valdez.
Thompson Pass could see gusts over 40 mph. Sustained winds of
small-craft advisory strength are also expected for Kachemak Bay,
Passage Canal, Resurrection Bay, and the Valdez Narrows. Westerly
gales are likely today across the Barren Islands.

Winds will diminish by late Saturday afternoon or evening as the
ridge moves overhead. Expect clearing skies as well, leading to
much cooler overnight temperatures this weekend. Overnight low
temperatures Saturday morning could drop into the upper 30s for
locations in the interior with the potential for overnight lows
Sunday morning to drop below freezing across the Copper River
Basin.

&&

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

A cold front has moved east of the area. In its wake we will see
lingering cloud cover, but dry conditions. Tonight high pressure
will move across Southwest Alaska this will allow clouds to clear
this evening with temperatures dropping into the 30s and lower
40s. Fog is not expected as drier air is expected Saturday
morning. Saturday the high pressure ridge will move east with a
front approaching coastal areas with increasing clouds and chances
of rain. Sunday the front will push inland as the upper level
trough pushes the system east. This front will bring rain across
most of the area on Sunday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Today through Sunday)...

A low pressure system south of Adak and an accompanying warm
frontal system will move north into the Bering today bringing
periods of moderate rain and small craft winds to the central and
eastern Bering. The front will then move into the AKPEN and
eastern Bering tonight and Saturday with areas of small craft
winds and gusts near Gale force especially in the gaps north of
the AKPEN and near Cold Bay. Another shortwave will move towards
Unalaska and into the eastern Bering on Saturday reinforcing the
warm front with more rain and areas of small crafts. On Sunday the
occluded portion of the warm front will move into the northern
and eastern Bering and across the AKPEN and move into Southwest
Alaska. Expect areas of fog across the western Bering today due to
warm air advection and expanding towards the Pribilofs tonight
and then into the eastern Bering Saturday and Sunday.

&&

.MARINE (Days 3 through 5)...
Expect winds less than 35 kts and seas less than 20 ft for the
Day 3 through 5 period. The only potential exception is there
could be a swath of Gale force winds along the southern Kenai
Peninsula coastline Sunday night into Monday.

&&

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

A seasonable pattern is in place on Monday with a vertically
stacked low over Bristol Bay with a front extending into the Gulf
of Alaska. This will bring widespread rain over Southcentral and
showers across parts of Southwest. The upper level low will be
slow to move through mid week but will eventually head eastward
and into the northeastern Gulf of Alaska and weaken through
Wednesday. With the large upper low in the Arctic persisting,
southern mainland Alaska will see a series of shortwaves through
the week next week. Each of these waves will bring with it some
rain showers.

A weak low is expected to track over the Aleutian Islands and
Alaska Peninsula Tuesday through Wednesday bringing some rain.
High pressure should build in from the west over the Central
Aleutians Wednesday and to the Alaska Peninsula Thursday. This
should provide a break in the rainfall, though there will likely
still be periods of low stratus in the northerly flow off the
Bering Sea.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 120 130 131.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MV
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RC
MARINE/LONG TERM...EZ