Small Craft Advisory 521, NWS Anchorage, AK

897 
FZAK52 PAFC 050003
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
403 PM AKDT Sat Jul 4 2020

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.

PKZ199-051330-
403 PM AKDT Sat Jul 4 2020
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A front moves across the Bering through Mon afternoon.

$$

PKZ150-051330-
South of the AK Peninsula Sitkinak to Castle Cape-
403 PM AKDT Sat Jul 4 2020

...SMALL CRAFT ADVISORY SUNDAY NIGHT...

.TONIGHT...SW wind 20 kt. Seas 5 ft. Patchy fog.
.SUN...SW wind 20 kt. Seas 5 ft. Patchy fog.
.SUN NIGHT...W wind 25 kt. Seas 7 ft. Patchy fog.
.MON AND MON NIGHT...NW wind 25 kt. Seas 7 ft.
.TUE THROUGH WED...W wind 20 kt. Seas 6 ft.
.THU...W wind 15 kt. Seas 4 ft.

$$

PKZ155-051330-
South of the AK Peninsula Castle Cape to Cape Sarichef-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...S wind 20 kt. Seas 6 ft. Patchy fog.
.SUN...SW wind 15 kt. Seas 5 ft. Patchy fog.
.SUN NIGHT...W wind 20 kt. Seas 6 ft. Patchy fog.
.MON AND MON NIGHT...W wind 20 kt. Seas 5 ft.
.TUE THROUGH THU...W wind 15 kt. Seas 7 ft.

$$

PKZ160-051330-
Bristol Bay-
403 PM AKDT Sat Jul 4 2020

...SMALL CRAFT ADVISORY SUNDAY NIGHT...

.TONIGHT...SE wind 10 kt becoming SW after midnight. 
Seas 3 ft. Patchy fog.
.SUN...SW wind 10 kt increasing to 15 kt in the afternoon. 
Seas 2 ft. Patchy fog.
.SUN NIGHT...W wind 15 kt increasing to 25 kt after midnight. 
Seas 5 ft. Patchy fog.
.MON AND MON NIGHT...W wind 25 kt. Seas 6 ft.
.TUE...W wind 20 kt. Seas 5 ft.
.WED THROUGH THU...W wind 15 kt. Seas 4 ft.

$$

PKZ165-051330-
Port Heiden to Cape Sarichef-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...S wind 20 kt. Seas 4 ft. Patchy fog.
.SUN...W wind 15 kt. Seas 3 ft. Patchy fog.
.SUN NIGHT...W wind 20 kt. Seas 4 ft. Patchy fog.
.MON...W wind 20 kt. Seas 5 ft.
.MON NIGHT...W wind 15 kt. Seas 5 ft.
.TUE...W wind 15 kt. Seas 5 ft.
.WED...Variable wind 10 kt. Seas 3 ft.
.THU...NW wind 15 kt. Seas 4 ft.

$$

PKZ170-051330-
Cape Sarichef to Nikolski Bering Side-
403 PM AKDT Sat Jul 4 2020

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...S wind 25 kt becoming W 15 kt after midnight. 
Seas 5 ft. Patchy fog.
.SUN...NW wind 15 kt. Seas 4 ft. Patchy fog.
.SUN NIGHT...W wind 15 kt. Seas 4 ft. Patchy fog.
.MON AND MON NIGHT...SW wind 15 kt. Seas 5 ft.
.TUE...S wind 15 kt. Seas 5 ft.
.WED...Variable wind 10 kt. Seas 4 ft.
.THU...Variable wind 10 kt. Seas 2 ft.

$$

PKZ171-051330-
Unalaska Bay-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...S wind 20 kt becoming NW 10 kt after midnight. 
Seas 2 ft. Patchy fog. Rain.
.SUN AND SUN NIGHT...NW wind 15 kt. Seas 2 ft. Patchy fog.
.MON...W wind 15 kt. Seas 3 ft.
.MON NIGHT...Variable wind less than 10 kt. Seas 3 ft.
.TUE THROUGH WED...S wind 10 kt. Seas 3 ft.
.THU...Variable wind less than 10 kt. Seas 2 ft.

$$

PKZ172-051330-
Cape Sarichef to Nikolski Pacific Side-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...S wind 20 kt. Seas 6 ft. Patchy fog.
.SUN AND SUN NIGHT...NW wind 20 kt. Seas 6 ft. Patchy fog.
.MON AND MON NIGHT...Variable wind 10 kt. Seas 5 ft.
.TUE THROUGH WED...S wind 15 kt. Seas 8 ft.
.THU...Variable wind 10 kt. Seas 6 ft.

$$

PKZ173-051330-
Nikolski to Seguam Island Bering Side-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...W wind 15 kt. Seas 5 ft. Patchy fog.
.SUN...Variable wind 10 kt. Seas 4 ft. Patchy fog.
.SUN NIGHT...SW wind 15 kt. Seas 5 ft. Patchy fog.
.MON...SW wind 15 kt. Seas 5 ft.
.MON NIGHT...Variable wind 10 kt. Seas 5 ft.
.TUE THROUGH WED...SE wind 15 kt. Seas 5 ft.
.THU...Variable wind 10 kt. Seas 4 ft.

$$

PKZ174-051330-
Nikolski to Seguam Island Pacific Side-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...W wind 15 kt. Seas 6 ft. Patchy fog.
.SUN...NW wind 15 kt. Seas 6 ft. Patchy fog.
.SUN NIGHT...Variable wind 10 kt. Seas 5 ft. Patchy fog.
.MON...Variable wind 10 kt. Seas 5 ft.
.MON NIGHT...SE wind 20 kt. Seas 6 ft.
.TUE...SE wind 20 kt. Seas 7 ft.
.WED...S wind 15 kt. Seas 7 ft.
.THU...Variable wind 10 kt. Seas 6 ft.

$$

PKZ175-051330-
Seguam Island to Adak Bering Side-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...W wind 15 kt. Seas 4 ft. Patchy fog.
.SUN AND SUN NIGHT...SW wind 20 kt. Seas 5 ft. Patchy fog.
.MON...S wind 15 kt. Seas 5 ft.
.MON NIGHT...SE wind 15 kt. Seas 4 ft.
.TUE...SE wind 15 kt. Seas 5 ft.
.WED THROUGH THU...Variable wind 10 kt. Seas 4 ft.

$$

PKZ176-051330-
Seguam Island to Adak Pacific Side-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...W wind 15 kt. Seas 7 ft. Patchy fog.
.SUN...SW wind 15 kt. Seas 6 ft. Patchy fog.
.SUN NIGHT...SW wind 15 kt. Seas 5 ft. Patchy fog.
.MON AND MON NIGHT...E wind 15 kt. Seas 5 ft.
.TUE THROUGH WED...E wind 15 kt. Seas 6 ft.
.THU...Variable wind 10 kt. Seas 6 ft.

$$

PKZ177-051330-
Adak to Kiska-
403 PM AKDT Sat Jul 4 2020

...SMALL CRAFT ADVISORY SUNDAY...

.TONIGHT...SW wind 20 kt. Seas 7 ft. Patchy fog.
.SUN...SW wind 25 kt. Seas 7 ft. Patchy fog.
.SUN NIGHT...SW wind 20 kt. Seas 6 ft. Patchy fog.
.MON...S wind 15 kt. Seas 6 ft.
.MON NIGHT...E wind 15 kt. Seas 6 ft.
.TUE THROUGH THU...NE wind 15 kt. Seas 6 ft.

$$

PKZ178-051330-
Kiska to Attu-
403 PM AKDT Sat Jul 4 2020

...SMALL CRAFT ADVISORY THROUGH SUNDAY NIGHT...

.TONIGHT...SW wind 25 kt. Seas 9 ft. Patchy fog.
.SUN...SW wind 25 kt. Seas 10 ft. Patchy fog.
.SUN NIGHT...S wind 20 kt. Seas 9 ft. Patchy fog.
.MON...S wind 20 kt. Seas 7 ft.
.MON NIGHT...SE wind 15 kt. Seas 6 ft.
.TUE THROUGH THU...NE wind 15 kt. Seas 6 ft.

$$

PKZ179-051330-
Pribilof Islands Near Shore Waters-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...S wind 20 kt. Seas 6 ft. Areas of fog.
.SUN...W wind 15 kt. Seas 5 ft. Patchy fog.
.SUN NIGHT...SW wind 20 kt. Seas 6 ft. Patchy fog.
.MON AND MON NIGHT...SW wind 20 kt. Seas 7 ft.
.TUE...S wind 15 kt. Seas 6 ft.
.WED...Variable wind 10 kt. Seas 4 ft.
.THU...Variable wind 10 kt. Seas 4 ft.

$$

PKZ180-051330-
Kuskokwim Delta and Etolin Strait-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...S wind 15 kt. Seas 4 ft. Patchy fog.
.SUN...SW wind 10 kt becoming W in the afternoon. 
Seas 4 ft. Patchy fog.
.SUN NIGHT...W wind 20 kt. Seas 4 ft. Patchy fog.
.MON AND MON NIGHT...W wind 20 kt. Seas 5 ft.
.TUE...W wind 20 kt. Seas 5 ft.
.WED THROUGH THU...NW wind 15 kt. Seas 4 ft.

$$

PKZ181-051330-
North and West of Nunivak Island-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...SE wind 20 kt. Seas 5 ft. Patchy fog.
.SUN...SW wind 15 kt. Seas 5 ft. Patchy fog.
.SUN NIGHT...SW wind 20 kt. Seas 4 ft. Patchy fog.
.MON AND MON NIGHT...SW wind 20 kt. Seas 6 ft.
.TUE...SW wind 20 kt. Seas 6 ft.
.WED THROUGH THU...W wind 15 kt. Seas 4 ft.

$$

PKZ185-051330-
Saint Matthew Island Waters-
403 PM AKDT Sat Jul 4 2020

.TONIGHT...S wind 20 kt. Seas 7 ft. Patchy fog.
.SUN AND SUN NIGHT...SW wind 20 kt. Seas 7 ft. Patchy fog.
.MON AND MON NIGHT...SW wind 20 kt. Seas 7 ft.
.TUE...SW wind 20 kt. Seas 7 ft.
.WED...SW wind 15 kt. Seas 4 ft.
.THU...Variable wind 10 kt. Seas 4 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
450 PM AKDT Fri Jul 3 2020

.ANALYSIS AND UPPER LEVELS...
The upper ridge over western Alaska/Alaska Peninsula has weakened
and allowed minor short waves to propagate eastward. One such wave
brought widespread rain/showers to Bristol Bay and the western
Gulf Alaska. The remainder of Southwest Alaska was under generally
cloudy skies. Upper Support for gusty outflow conditions
diminished along the North Gulf Coast and eastern Kenai Peninsula
which was evidenced by a shift to afternoon sea breezes in these
areas. Further west, a weather front over the western Bering
Sea/west Aleutians produced rain and gusty southerly winds to the
area.

&&

.MODEL DISCUSSION...
With the exception of minor timing issues with upper waves, the
models are in generally good agreement with the synoptic features.
The main areas of work will be thunderstorms across Southcentral
over the weekend.

&&

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

&&

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

The major concern for the Independence Day holiday weekend will
be the approaching strong shortwave aloft from the Interior Saturday
afternoon. As this feature descends southeastward across the
northern Susitna Valley, Talkeetna Mountains, and Copper River
Basin, it will encounter a hot and unstable airmass leading to a
high potential for hazardous weather. Expect an organized area of
thunderstorms to develop ahead of the short-wave, producing
frequent lightning, small hail and heavy rain. This seems like one
of the few instances where thunderstorms will persists all night
long as the short-wave continues to track across the Copper River
Basin. Showers and thunderstorms will taper off Sunday as the
short-wave exits the region.

Meanwhile, warm and dry conditions will continue across much of
the remainder of Southcentral. Subsidence will increase as an
upper level ridge builds in behind the aforementioned short-wave
Sunday through Monday. This ridge will advect moisture and
elevate cloud cover over Southcentral by Monday morning, leading
to a cooling trend.

In the last couple days, strong offshore flow led to hot
temperatures along the coast, with mid 70s to near 80 in Seward,
Whittier, Valdez, and Cordova. Offshore flow will weaken this
afternoon through tonight, with a more normal sea breeze pattern
establishing itself in the coming days. Thus, expect temperatures
to drop significantly from the lofty highs of the past couple days
back to near normal.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tonight
through Monday)...

A lead impulse, ahead of a large disturbance, will pass by just to
the north and east of the lower Kuskokwim valley this evening.
Daytime heading and cooling aloft with the impulse will allow for
some weak instability to develop. This may be enough for an
isolated thunderstorm or two to develop, mainly north and east of
Sleetmute. As such, this was added to the forecast.

Otherwise, the ridge of high pressure will shift eastward as a
Bering front approaches. Disturbances in the developing southwest
flow aloft will begin to affect the region for the weekend. This
will allow for some showers to develop Both days. A few
thunderstorms are also possible on Sunday as instability once
again increases. At this time, the favored areas for potential
thunderstorm development looks to be east of the Kuskokwim
Mountains and from the Nushagak Hills northward for Sunday
afternoon/evening. That said, the instability is fairly weak, as
numerical guidance indicates MUCAPEs of 100-500 J/kg with Lifted
Indices (LI's) of -1 to -3. This combined with less than 20 knots
of 0-6km bulk shear will help mitigate thunderstorm coverage.

&&

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

Widespread patchy fog was added to the forecast for the remainder
of this afternoon through tomorrow, as area web cams and numerous
land-based and ship observations indicated visibilities lingering
in the 1 1/2 to 6 statue mile range. However, various satellite
imagery also suggests this is patchy in nature. This may change
locally overnight though, as light winds and abundant low level
moisture will allow fog to develop across the Pribilof Islands,
and to a lesser extend across portions of the eastern Aleutians
and tip of the Alaska Peninsula.

Otherwise, a front attached to a western Pacific low, will
continue its eastward trek through Saturday with widespread
showers accompanying it, aided by shortwave disturbances crossing
the region in the southwesterly flow aloft. By Sunday, this front
begins to weaken (frontolysis), as it outruns its upper-level
support, as the Pacific low reaches Siberia while weakening.

&&

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

Gulf of Alaska: Easterly winds become Westerly as high pressure
slides across the Gulf through Tue. A front enters the Western
Gulf Mon. Confidence is good for small craft winds and waves East
of the Shumagin Islands with Gale force winds and higher waves
developing South of Kodiak Island through Tue.

Aleutians and Bering: A trough extending from a Northwest Bering
low sweeps the Western Aleutians. Confidence is good for small
craft winds and waves over the Western Aleutians and Bering for
Sun. A front pushes through Bristol Bay. Confidence is good for
small craft winds and waves over the Eastern Bering and Bristol
Bay Mon and Tue.

&&

LONG TERM FORECAST (Days 4 through 7: Monday through Thursday)...

The strong upper ridge over western Alaska Sunday weakens through
Wednesday. This allows short waves spinning off of the Bering Sea
trough to progress eastward across the Mainland. This pattern
change will bring intrusions of moisture from the west resulting
in cloudier conditions, increased chances of rain/showers, and a
lowering of daytime high temperatures across the southern
Mainland. Although the model trends are similar with the weakening
of the upper ridge, differences in solutions will pose a problem
in timing systems. So confidence is low on exact timing but fair
to good on a trend toward more clouds, cooler temperatures, and
chances of rain.

With the main upper low center and trough holding over the Bering
Sea expect generally mostly cloudy conditions with periods of
rain/showers, and gusty winds.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...Red Flag Warning 141.

&&

SYNOPSIS AND MODEL DISCUSSION...BC
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
MARINE/LONG TERM...MK/BC