Small Craft Advisory 559, NWS Anchorage, AK

119 
FZAK52 PAFC 302251
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
251 PM AKDT Sun Jul 30 2017

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.

PKZ199-311145-
251 PM AKDT Sun Jul 30 2017
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A front over the Western Bering Sea will move toward the Bering
Strait Sun night then weaken through Mon night with a weak trough
of low pressure remaining over the Bering Sea. An area of low
pressure and a stronger front will move toward the Western 
Aleutians late Mon night.

$$

PKZ150-311145-
South of the AK Peninsula Sitkinak to Castle Cape-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...NE wind 20 kt. Seas 5 ft.
.MON...NE wind 20 kt. Seas 5 ft.
.MON NIGHT...E wind 15 kt. Seas 5 ft.
.TUE...NE wind 15 kt. Seas 5 ft.
.TUE NIGHT...NW wind 15 kt. Seas 5 ft.
.WED...Variable wind 10 kt. Seas 5 ft.
.THU THROUGH FRI...Variable wind 10 kt. Seas 4 ft.

$$

PKZ155-311145-
South of the AK Peninsula Castle Cape to Cape Sarichef-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...Variable wind 10 kt. Seas 4 ft.
.MON...E wind 15 kt. Seas 4 ft.
.MON NIGHT...Variable wind 10 kt. Seas 4 ft.
.TUE AND TUE NIGHT...Variable wind 10 kt. Seas 5 ft.
.WED THROUGH FRI...W wind 15 kt. Seas 6 ft.

$$

PKZ160-311145-
Bristol Bay-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...W wind 10 kt. Seas 3 ft. Areas of fog.
.MON...S wind 10 kt increasing to 15 kt in the afternoon. Seas 3
ft. Areas of fog.
.MON NIGHT...S wind 15 kt. Seas 3 ft.
.TUE AND TUE NIGHT...SW wind 15 kt. Seas 3 ft.
.WED...SW wind 15 kt. Seas 4 ft.
.THU THROUGH FRI...SW wind 10 kt. Seas 4 ft.

$$

PKZ165-311145-
Port Heiden to Cape Sarichef-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...Variable wind 10 kt. Seas 3 ft. Patchy fog.
.MON...S wind 20 kt. Seas 4 ft. Patchy fog. Rain.
.MON NIGHT...S wind 20 kt. Seas 4 ft. Patchy fog. Rain.
.TUE AND TUE NIGHT...SW wind 15 kt. Seas 5 ft.
.WED THROUGH FRI...W wind 15 kt. Seas 7 ft.

$$

PKZ170-311145-
Cape Sarichef to Nikolski Bering Side-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...Variable wind 10 kt. Seas 4 ft. Patchy fog.
.MON...SW wind 20 kt. Seas 5 ft. Patchy fog. Rain.
.MON NIGHT...SW wind 15 kt. Seas 5 ft. Patchy fog.
.TUE AND TUE NIGHT...SW wind 15 kt. Seas 5 ft.
.WED...SW wind 20 kt. Seas 6 ft.
.THU THROUGH FRI...W wind 15 kt. Seas 9 ft.

$$

PKZ171-311145-
Unalaska Bay-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...W wind 10 kt in the evening becoming variable less than
10 kt. Seas 2 ft. Patchy fog.
.MON...Variable wind less than 10 kt becoming S 10 kt in the
afternoon. Seas 2 ft. Patchy fog. Rain.
.MON NIGHT...W wind 15 kt diminishing to 10 kt after midnight.
Seas 2 ft. Patchy fog. Rain.
.TUE AND TUE NIGHT...W wind 15 kt. Seas 2 ft.
.WED...SW wind 15 kt. Seas 2 ft.
.THU THROUGH FRI...W wind 10 kt. Seas 2 ft.

$$

PKZ172-311145-
Cape Sarichef to Nikolski Pacific Side-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...Variable wind 10 kt. Seas 3 ft.
.MON...SW wind 15 kt. Seas 4 ft.
.MON NIGHT...SW wind 15 kt. Seas 4 ft.
.TUE AND TUE NIGHT...W wind 15 kt. Seas 4 ft.
.WED...SW wind 20 kt. Seas 6 ft.
.THU THROUGH FRI...W wind 15 kt. Seas 7 ft.

$$

PKZ173-311145-
Nikloski to Seguam Island Bering Side-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...SW wind 15 kt. Seas 4 ft. Patchy fog.
.MON...SW wind 20 kt. Seas 5 ft. Patchy fog.
.MON NIGHT...W wind 20 kt. Seas 6 ft. Patchy fog.
.TUE...W wind 15 kt. Seas 6 ft.
.TUE NIGHT...S wind 25 kt. Seas 5 ft.
.WED...SW wind 25 kt. Seas 7 ft.
.THU THROUGH FRI...W wind 15 kt. Seas 8 ft.

$$

PKZ174-311145-
Nikolski to Seguam Island Pacific Side-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...W wind 15 kt. Seas 4 ft. Patchy fog.
.MON...SW wind 15 kt. Seas 5 ft. Patchy fog.
.MON NIGHT...W wind 20 kt. Seas 6 ft. Patchy fog.
.TUE...W wind 15 kt. Seas 5 ft.
.TUE NIGHT...SW wind 20 kt. Seas 5 ft.
.WED...SW wind 25 kt. Seas 10 ft.
.THU THROUGH FRI...W wind 20 kt. Seas 8 ft.

$$

PKZ175-311145-
Seguam Island to Adak Bering Side-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...SW wind 20 kt. Seas 5 ft. Patchy fog.
.MON...SW wind 20 kt. Seas 6 ft. Patchy fog.
.MON NIGHT...SW wind 20 kt. Seas 6 ft. Patchy fog.
.TUE...SW wind 20 kt. Seas 5 ft.
.TUE NIGHT...S wind 25 kt. Seas 8 ft.
.WED...SW wind 25 kt. Seas 8 ft.
.THU...W wind 15 kt. Seas 6 ft.
.FRI...W wind 20 kt. Seas 6 ft.

$$

PKZ176-311145-
Seguam Island to Adak Pacific Side-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...W wind 15 kt. Seas 4 ft. Patchy fog.
.MON...W wind 15 kt. Seas 4 ft. Patchy fog.
.MON NIGHT...W wind 15 kt. Seas 4 ft. Patchy fog.
.TUE...SW wind 20 kt. Seas 4 ft.
.TUE NIGHT...S wind 25 kt. Seas 11 ft.
.WED...SW wind 25 kt. Seas 12 ft.
.THU THROUGH FRI...W wind 20 kt. Seas 8 ft.

$$

PKZ177-311145-
Adak to Kiska-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...SW wind 20 kt. Seas 5 ft. Areas of fog.
.MON...SW wind 20 kt. Seas 6 ft. Patchy fog.
.MON NIGHT...SW wind 20 kt. Seas 5 ft. Patchy fog.
.TUE AND TUE NIGHT...S wind 30 kt. Seas 13 ft.
.WED...SW wind 25 kt. Seas 13 ft.
.THU THROUGH FRI...W wind 20 kt. Seas 7 ft.

$$

PKZ178-311145-
Kiska to Attu-
251 PM AKDT Sun Jul 30 2017

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...SW wind 25 kt. Seas 7 ft. Patchy fog. Rain.
.MON...SW wind 20 kt. Seas 6 ft. Patchy fog. Rain.
.MON NIGHT...S wind 20 kt. Seas 6 ft. Patchy fog.
.TUE...SE wind 30 kt. Seas 15 ft.
.TUE NIGHT...S wind 25 kt. Seas 14 ft.
.WED...W wind 20 kt. Seas 11 ft.
.THU THROUGH FRI...SW wind 15 kt. Seas 8 ft.

$$

PKZ179-311145-
Pribilof Islands Near Shore Waters-
251 PM AKDT Sun Jul 30 2017

...SMALL CRAFT ADVISORY MONDAY...

.TONIGHT...SW wind 10 kt in the evening increasing to 20 kt. Seas 5 
ft. Areas of fog. Rain.
.MON...SW wind 25 kt. Seas 6 ft. Areas of fog. Rain.
.MON NIGHT...W wind 15 kt. Seas 6 ft. Patchy fog.
.TUE AND TUE NIGHT...SW wind 15 kt. Seas 6 ft.
.WED...S wind 15 kt. Seas 7 ft.
.THU THROUGH FRI...W wind 15 kt. Seas 9 ft.

$$

PKZ180-311145-
Kuskokwim Delta and Etolin Strait-
251 PM AKDT Sun Jul 30 2017

...SMALL CRAFT ADVISORY MONDAY AND MONDAY NIGHT...

.TONIGHT...S wind 10 kt in the evening increasing to 20 kt. Seas 4 
ft. Patchy fog.
.MON...S wind 30 kt. Seas 6 ft. Areas of fog. Rain.
.MON NIGHT...S wind 30 kt becoming SW 20 kt after midnight. Seas
6 ft. Patchy fog.
.TUE AND TUE NIGHT...SW wind 15 kt. Seas 5 ft.
.WED...SW wind 15 kt. Seas 4 ft.
.THU THROUGH FRI...W wind 10 kt. Seas 7 ft.

$$

PKZ181-311145-
North and West of Nunivak Island-
251 PM AKDT Sun Jul 30 2017

...SMALL CRAFT ADVISORY THROUGH MONDAY...

.TONIGHT...S wind 15 kt in the evening increasing to 25 kt. Seas 6 
ft. Patchy fog.
.MON...S wind 25 kt. Seas 6 ft. Patchy fog. Rain.
.MON NIGHT...Variable wind 10 kt. Seas 5 ft. Patchy fog.
.TUE AND TUE NIGHT...SW wind 15 kt. Seas 4 ft.
.WED THROUGH FRI...Variable wind 10 kt. Seas 6 ft.

$$

PKZ185-311145-
Saint Matthew Island Waters-
251 PM AKDT Sun Jul 30 2017

.TONIGHT...SW wind 20 kt. Seas 6 ft. Patchy fog.
.MON...SW wind 15 kt. Seas 6 ft. Patchy fog.
.MON NIGHT...SW wind 15 kt. Seas 5 ft. Patchy fog.
.TUE AND TUE NIGHT...SW wind 15 kt. Seas 4 ft.
.WED...S wind 15 kt. Seas 9 ft.
.THU THROUGH FRI...Variable wind 10 kt. Seas 8 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
432 PM AKDT Sat Jul 29 2017

.ANALYSIS AND UPPER LEVELS...
The upper level ridge that has been protruding into the Bering
Sea persists today with broad low pressure over the mainland part
of the state. A stronger upper level low is in the eastern Gulf
with a weak upper level low that has just dropped south of the
Alaska Peninsula. The 250 mb jet stream is running through the
western Bering Sea and then taking a sharp turn to the south over
the central Bering Sea and accelerating between the low near the
Ak Peninsula and the ridge. While the flow is very slack at the
250 mb level over the mainland part of the state, there is a weak
easterly flow at the 700 to 500 mb level over Southcentral Alaska
and the Gulf. This is steering some weak upper level disturbances
over the area from the east resulting in some showers. The
thunderstorm threat is mainly over the more unstable air near the
Alaska Range and Talkeetna Mountains.

&&

.MODEL DISCUSSION...
The models remain in good overall synoptic agreement into early
next week. AS is typical with the weak systems this time of year
the details where the forecast is made or broken is where there is
differences. The weak upper level waves over Southcentral are
changing from model run to model run which is not a big surprise,
but it does increase the uncertainty as to when the batches of
showers will move through.
The GFS and NAM are both showing similar locations for the most
unstable air the next two or three day, but the NAM is indicating
much greater values as it often does. This is not too much of a
factor except for the areas west of the Alaska Range where it make
the call on thunderstorms a bit more difficult.

&&

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

&&

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

Cloud cover continues to be quite stubborn this afternoon with a
few breaks being observed over west Anchorage and parts of the
Kenai Peninsula and Susitna Valley. This is in response to a weak
wave that brought a few rain showers during the early morning
hours and upslopes moisture over the terrain of Southcentral
Alaska. Subsidence behind the weak wave should allow for cloud
cover to break and the lingering shower activity to diminish.
Looking north toward the Susitna Valley and Copper River Basin,
agitated cumulus clouds are developing as low-level lapse rates
are steepening as a thermal trough begins to develop over the
region. It's likely that several thunderstorms will likely develop
along the Alaska Range and Talkeetna Mountains this afternoon and
evening but weak steering flow aloft should keep thunderstorms
along the mountains instead of drifting too far into the valley.
Thunderstorm activity will dwindle overnight as the sfc stabilizes
but will quickly return by late morning on Sunday to the Susitna
Valley and Copper River Basin as temperatures quickly warm.
Thunderstorm coverage will be much more extensive Sunday with most
of the aforementioned locations plus Hatcher Pass possibly seeing
thunderstorms. Otherwise, most locations across Southcentral
Alaska should largely remain on the dry side with weak offshore
flow helping to keep coastal locations on the dry side.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Weak ridging over the area will inhibit rain in the cooler
nighttime hours through the weekend but afternoon heating will
allow for shower activity in the afternoon/evening. There is also
enough instability on Sunday for possible thunderstorms through a
corridor from Bristol Bay to the Middle Kuskokwim Valley. On
Monday a front moving through the Bering will make it to the
Kuskokwim Delta by the afternoon and then to the rest of southwest
Alaska Monday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Ridging will remain over much of the southern Bering and Aleutians
through Monday keeping fog and stratus around these areas. On
Sunday a front will move into the western Bering and then track
east making it to the eastern Bering Monday morning. The front
will be draped across the central Bering bringing rain to the
Pribilof Islands.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The general pattern of a broad upper level ridge over the North
Pacific and Aleutians with westerly flow across the Bering will
continue into early next week. An upper level trough and frontal
system pushing into Southwest Alaska Monday night will continue to
spread east as a low in the southern Gulf sends a frontal system
north to the central Gulf Tuesday and northern Gulf coast Tuesday
night. These to frontal systems will both converge over Southcentral
Alaska around Wednesday. The same general pattern will continue
through the remainder of the the week with frontal systems coming
in from the west, riding in up over top the Aleutian ridge and
frontal systems lifting north into the Gulf. Eventually also
arctic troughs from the north will start digging south beginning
around next weekend. Although there is a lot more model
uncertainty regarding the time of these and the amount of cold air
they will bring, the general trend seems reasonable given the
time of year.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...MC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...JR