Small Craft Advisory 360, NWS Anchorage, AK

474 
FZAK52 PAFC 032300
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
300 PM AKDT Thu May 3 2018

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.

PKZ199-041215-
300 PM AKDT Thu May 3 2018
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A complex 989 mb low 160 nm northwest of Dutch Harbor moves 50 nm
south of Chignik at 974 mb tonight then it will move inland Fri 
afternoon at 973 mb. A 996 mb low approaches the western Aleutians
Sat afternoon.

$$

PKZ150-041215-
South of the AK Peninsula Sitkinak to Castle Cape-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY...

.TONIGHT...SE wind 30 kt becoming S 40 kt after midnight. Seas 9
ft building to 14 ft after midnight. Rain.
.FRI...SW wind 45 kt. Seas 18 ft.
.FRI NIGHT...S wind 30 kt. Seas 15 ft.
.SAT...SW wind 25 kt. Seas 12 ft.
.SAT NIGHT...SW wind 20 kt. Seas 8 ft.
.SUN...S wind 20 kt. Seas 7 ft.
.MON THROUGH TUE...SE wind 30 kt. Seas 15 ft.

$$

PKZ155-041215-
South of the AK Peninsula Castle Cape to Cape Sarichef-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY...

.TONIGHT...W wind 30 kt. From the Shumagin Islands E, SE wind 30
kt becoming SW 40 kt after midnight. Seas 12 ft. Widespread rain and
snow showers.
.FRI...W wind 30 kt. From the Shumagin Islands E, SW wind 40 kt
diminishing to 30 kt in the afternoon. Seas 13 ft.
.FRI NIGHT...W wind 30 kt. Seas 12 ft.
.SAT...W wind 25 kt. Seas 10 ft.
.SAT NIGHT...SW wind 20 kt. Seas 7 ft.
.SUN...S wind 30 kt. Seas 9 ft.
.MON...S wind 30 kt. Seas 19 ft.
.TUE...S wind 25 kt. Seas 19 ft.

$$

PKZ160-041215-
Bristol Bay-
300 PM AKDT Thu May 3 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...SE wind 15 kt becoming NE 30 kt after midnight. Seas
5 ft. Patchy fog. Rain.
.FRI...NE wind 30 kt becoming SW in the afternoon. Seas 7 ft.
Rain.
.FRI NIGHT...SW wind 30 kt. Seas 8 ft. Rain showers.
.SAT...SW wind 25 kt. Seas 9 ft.
.SAT NIGHT...SW wind 20 kt. Seas 7 ft.
.SUN THROUGH TUE...SE wind 30 kt. Seas 6 ft.

$$

PKZ165-041215-
Port Heiden to Cape Sarichef-
300 PM AKDT Thu May 3 2018

...SMALL CRAFT ADVISORY FRIDAY AND FRIDAY NIGHT...

.TONIGHT...NW wind 15 kt except E 20 kt from Port Moller E. Seas
6 ft.
.FRI...NW wind 20 kt increasing to 30 kt in the afternoon. From
Port Moller E, NW wind 30 kt. Seas 9 ft. Rain showers and snow.
.FRI NIGHT...W wind 30 kt. Seas 13 ft. Rain showers.
.SAT...W wind 25 kt. Seas 11 ft.
.SAT NIGHT...SW wind 20 kt. Seas 8 ft.
.SUN...S wind 30 kt. Seas 6 ft.
.MON...SE wind 25 kt. Seas 10 ft.
.TUE...SE wind 20 kt. Seas 6 ft.

$$

PKZ170-041215-
Cape Sarichef to Nikolski Bering Side-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY...

.TONIGHT...W wind 25 kt becoming NW 35 kt after midnight. Seas
13 ft. Rain showers.
.FRI...NW wind 35 kt. Seas 17 ft. Rain showers.
.FRI NIGHT...NW wind 30 kt. Seas 15 ft.
.SAT...W wind 20 kt. Seas 12 ft.
.SAT NIGHT...SW wind 15 kt. Seas 8 ft.
.SUN...S wind 30 kt. Seas 9 ft.
.MON...S wind 25 kt. Seas 12 ft.
.TUE...W wind 25 kt. Seas 14 ft.

$$

PKZ171-041215-
Unalaska Bay-
300 PM AKDT Thu May 3 2018

...GALE WARNING FRIDAY...

.TONIGHT...W wind 20 kt. Seas 3 ft building to 5 ft after
midnight. Rain showers and snow showers.
.FRI...NW wind 35 kt. Seas 15 ft. Rain showers and snow showers.
.FRI NIGHT...NW wind 30 kt. Seas 13 ft. Snow showers.
.SAT...W wind 20 kt. Seas 3 ft.
.SAT NIGHT...SW wind 10 kt. Seas 2 ft.
.SUN...S wind 25 kt. Seas 4 ft.
.MON...S wind 15 kt. Seas 2 ft.
.TUE...W wind 20 kt. Seas 3 ft.

$$

PKZ172-041215-
Cape Sarichef to Nikolski Pacific Side-
300 PM AKDT Thu May 3 2018

...GALE WARNING FRIDAY...

.TONIGHT...W wind 30 kt. Seas 11 ft. Rain showers and snow
showers.
.FRI...NW wind 35 kt. Seas 13 ft.
.FRI NIGHT...NW wind 30 kt. Seas 11 ft.
.SAT...W wind 20 kt. Seas 8 ft.
.SAT NIGHT...SW wind 15 kt. Seas 6 ft.
.SUN...S wind 35 kt. Seas 10 ft.
.MON...SW wind 25 kt. Seas 17 ft.
.TUE...W wind 30 kt. Seas 17 ft.

$$

PKZ173-041215-
Nikolski to Seguam Island Bering Side-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY...

.TONIGHT...NW wind 35 kt. Seas 12 ft building to 17 ft after
midnight. Rain showers.
.FRI...NW wind 35 kt. Seas 16 ft.
.FRI NIGHT...NW wind 30 kt becoming W 20 kt after midnight. Seas
15 ft.
.SAT...W wind 20 kt. Seas 10 ft.
.SAT NIGHT...SW wind 15 kt. Seas 7 ft.
.SUN...S wind 35 kt. Seas 13 ft.
.MON THROUGH TUE...NW wind 30 kt. Seas 15 ft.

$$

PKZ174-041215-
Nikolski to Seguam Island Pacific Side-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY...

.TONIGHT...NW wind 35 kt. Seas 13 ft. Rain showers.
.FRI...NW wind 35 kt. Seas 13 ft.
.FRI NIGHT...NW wind 30 kt. Seas 12 ft.
.SAT...W wind 20 kt. Seas 9 ft.
.SAT NIGHT...SW wind 15 kt. Seas 7 ft.
.SUN...S wind 40 kt. Seas 15 ft.
.MON THROUGH TUE...W wind 30 kt. Seas 18 ft.

$$

PKZ175-041215-
Seguam Island to Adak Bering Side-
300 PM AKDT Thu May 3 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...NW wind 30 kt. Seas 12 ft.
.FRI...NW wind 30 kt. Seas 13 ft.
.FRI NIGHT...NW wind 25 kt. Seas 13 ft.
.SAT...W wind 20 kt. Seas 9 ft.
.SAT NIGHT...SW wind 15 kt. Seas 6 ft.
.SUN...SE wind 30 kt. Seas 13 ft.
.MON THROUGH TUE...NW wind 30 kt. Seas 14 ft.

$$

PKZ176-041215-
Seguam Island to Adak Pacific Side-
300 PM AKDT Thu May 3 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...NW wind 30 kt. Seas 9 ft.
.FRI...NW wind 30 kt. Seas 10 ft.
.FRI NIGHT...NW wind 25 kt. Seas 10 ft.
.SAT...W wind 25 kt. Seas 9 ft.
.SAT NIGHT...SW wind 20 kt. Seas 6 ft.
.SUN...S wind 35 kt. Seas 13 ft.
.MON THROUGH TUE...NW wind 30 kt. Seas 14 ft.

$$

PKZ177-041215-
Adak to Kiska-
300 PM AKDT Thu May 3 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...NW wind 25 kt. Seas 9 ft.
.FRI...NW wind 25 kt. Seas 9 ft.
.FRI NIGHT...W wind 25 kt. Seas 10 ft.
.SAT...W wind 25 kt. Seas 9 ft.
.SAT NIGHT...S wind 25 kt. Seas 7 ft.
.SUN...N wind 35 kt. Seas 11 ft.
.MON...NW wind 35 kt. Seas 11 ft.
.TUE...NW wind 30 kt. Seas 11 ft.

$$

PKZ178-041215-
Kiska to Attu-
300 PM AKDT Thu May 3 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...NW wind 25 kt. Seas 9 ft.
.FRI...W wind 25 kt. Seas 9 ft.
.FRI NIGHT...W wind 25 kt. Seas 9 ft.
.SAT...W wind 20 kt. Seas 7 ft.
.SAT NIGHT...E wind 25 kt. Seas 8 ft.
.SUN THROUGH MON...NW wind 30 kt. Seas 12 ft.
.TUE...N wind 20 kt. Seas 10 ft.

$$

PKZ179-041215-
Pribilof Islands Near Shore Waters-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY...

.TONIGHT...N wind 35 kt. Seas 13 ft. Rain and snow showers.
.FRI...N wind 40 kt. Seas 16 ft.
.FRI NIGHT...NW wind 30 kt. Seas 12 ft.
.SAT...NW wind 20 kt. Seas 9 ft.
.SAT NIGHT...Variable wind 10 kt. Seas 7 ft.
.SUN...SE wind 25 kt. Seas 10 ft.
.MON...E wind 15 kt. Seas 12 ft.
.TUE...N wind 15 kt. Seas 9 ft.

$$

PKZ180-041215-
Kuskokwim Delta and Etolin Strait-
300 PM AKDT Thu May 3 2018

...GALE WARNING FRIDAY AND FRIDAY NIGHT...

.TONIGHT...NE wind 30 kt. Seas 6 ft. Patchy fog.
.FRI...NW wind 35 kt. Seas 9 ft. Rain.
.FRI NIGHT...NW wind 35 kt. Seas 11 ft.
.SAT...W wind 25 kt. Seas 10 ft.
.SAT NIGHT...SW wind 20 kt. Seas 7 ft.
.SUN THROUGH MON...SE wind 30 kt. Seas 7 ft.
.TUE...E wind 25 kt. Seas 6 ft.

$$

PKZ181-041215-
North and West of Nunivak Island-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY NIGHT...

.TONIGHT...N wind 35 kt. Seas 10 ft.
.FRI...N wind 35 kt. Seas 12 ft.
.FRI NIGHT...NW wind 35 kt. Seas 11 ft.
.SAT...NW wind 25 kt. Seas 9 ft.
.SAT NIGHT...W wind 20 kt. Seas 7 ft.
.SUN...SE wind 25 kt. Seas 6 ft.
.MON...E wind 25 kt. Seas 7 ft.
.TUE...E wind 20 kt. Seas 7 ft.

$$

PKZ185-041215-
Saint Matthew Island Waters-
300 PM AKDT Thu May 3 2018

...GALE WARNING THROUGH FRIDAY...

.TONIGHT...N wind 35 kt E of Saint Matthew Island...N 25 kt W of
Saint Matthew Island. Seas 8 ft.
.FRI...N wind 35 kt E of Saint Matthew Island...N 25 kt W of Saint
Matthew Island. Seas 10 ft.
.FRI NIGHT...N wind 30 kt. Seas 10 ft.
.SAT...N wind 25 kt. Seas 9 ft.
.SAT NIGHT...N wind 20 kt. Seas 7 ft.
.SUN THROUGH TUE...NE wind 30 kt. Seas 11 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
459 PM AKDT Wed May 2 2018

.ANALYSIS AND UPPER LEVELS...
The upper level shortwave that brought a round of late season
snowfall to the Matanuska Valley eastward into the Copper River
Basin and Thompson Pass areas overnight continues to slowly move
off to the east and dissipate. An area of weak high pressure
behind this shortwave brought a brief period of sunny skies to
Southcentral this morning, however this quickly filled in as
diurnal convection from the Kenai Peninsula spreads northward
towards the Anchorage Bowl. This area of convection even produced
some very small hail near the Soldotna area late this morning as
showers fell through low freezing levels. Further west over
Southwest Mainland this high pressure was too weak to provide much
relief from the stratus and areas of snow that developed,
allowing for widespread cloud cover to continue into this
afternoon. This is quickly beginning to fill in as the next
system approaches from the Eastern Bering. This low will be the
focus not only for another round of rain/snow and gusty easterly
winds for the Southwest Mainland, but also for a developing
triple point low that will develop in the Gulf on Thursday.

&&

.MODEL DISCUSSION...
The models remain in generally good synoptic scale agreement
through Thursday with the Eastern Bering low as it develops a
triple point low near the AKPen this evening. Ahead of this low,
none of the model guidance has handled the early diurnal convection
that has occurred over Southcentral well, as even the high
resolution models held off until late this afternoon to bring any
showers into the area. Afterwards there remains some uncertainty
in the low track and intensity of the low that will rapidly
develop under the Bering low and enter the Southwest Mainland for
Friday. The GFS in particular continues to be an outlier by
producing a deeper and further west position as the low makes
landfall late Friday. Since the GFS has been one of more variable
models with this system as it had previously been much further
east and deeper, this was treated as an outlier in favor of the
more consistent NAM and EC.

&&

.AVIATION...
PANC...The first question for early this evening will be for the
possible development of convective rain showers around the
terminal not only along the mountains be also around Cook Inlet as
showers from the Kenai Peninsula move northward. These should
generally be light and spotty with VFR conditions expected. Winds
will also shift to southeasterly and gust to around 20 kt this
evening as the gradient through Turnagain Arm increases.
Afterwards VFR conditions with light southeast winds are expected
into Thursday.

&&

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

A pattern shift in the upper level jet stream sets an active wet
and windy pattern into motion for the end of the week. The main
challenge in the forecast is focused around a storm system which
pushes across the Gulf on Thursday and then northward through
Southcentral Thursday night through Friday evening. Precipitation
with this storm system is primarily forecast as rain; however,
higher elevations over 1500 feet will stay cold enough to see all
snow and cooler locations inland changes over to light snow
during the night and early morning hours.

Gusty southeasterly winds and rain develop along the front which
is expected to move across Kodiak Island late this evening. The
frontal boundary moves quickly north making it to the Kenai and
north gulf coast by Thursday morning. The highest accumulations
are expected along the coast as abundant subtropical moisture
advects toward the southern mainland with the jet stream orienting
south to north as it noses along the Kenai on Friday. The jet
nudges toward the Alaska range into the the evening bringing the
best chance for accumulating rain across inland locations.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
A frontal system currently centered over the Pribilof Islands will
move east tonight and spread precipitation across the coast and up
the Kuskokwim River Valley tomorrow. Easterly winds will increase
tonight and tomorrow as the front lifts northward with the highest
gusts seen through the Kamishak Gap and across Lake Iliamna.

The system will retrograde back to the south Thursday night as a
vigorous upper level low drops south across the Aleutians,
swinging around the old low while spinning up a strong surface
low. This low will be supported by a stout southerly upper level
jet which will send the system north across the AKPEN and into the
Bristol Bay area by Friday afternoon. A long southerly fetch of
wind and moisture will slam into the southern AKPEN coast and will
spread across the SW interior. Rain will be focused over the
Bristol Bay area and the Kuskokwim River Valley Friday morning
before spreading north and west into the Kuskokwim Delta by the
afternoon. Warm air associated with this system will keep freezing
levels higher so precipitation should stay all rain for most
lower elevation sites. Another round of gusty winds across the
western side of the Alaska and Aleutian Ranges are also expected
with this system, with the strongest gusts seen through the
Kamishak Gap and across Lake Iliamna.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A series of low pressure systems will impact the eastern Bering
and Aleutian Island chain bringing strong winds and precipitation
to the area through the end of the week. The strongest low will
form south of Cold Bay Thursday evening and rapidly strengthen as
it moves north. Cold air wrapping around the backside of the low
combined with a tightening pressure gradient will lead to a
a narrow band of northerly gale force winds developing from the
Pribilofs south to Dutch Harbor Thursday night through Friday
evening. Conditions will be a bit quieter for the western half of
the Bering though cold northerly flow will lead to some snow
showers developing between Adak and Dutch Harbor through the end
of the week.

&&

.LONG TERM FORECAST (Days 3 through 7...Sat through Wed)...
The weekend will start out with yet another strong low pressure
system moving inland. This system will bring strong winds, heavy
rain, and even the chance for heavy snow for higher elevations.
The low pressure center at the surface will drive from south to
north across SW AK early Sat morning. This will bring strong winds
to parts of Kodiak Island, into Bristol Bay, and along the Gulf of
AK coastline. The difference with this system from yesterday is
that it does not hold together and move far enough north to spread
much of these winds inland across Southcentral and Cook Inlet.

This system will be interesting in how far south it taps into
moisture. The fetch will extend all the way down to nearly 30N.
This is known as an atmospheric river. And at least to start the
weekend, it will be pointed at the Gulf Coast. The heaviest
precipitation does slide slightly east late Sat, but is quickly
reinforced along the coast by another shortwave moving into the
area early Sun. This heavy precipitation will work in tandem with
some cold air that filters into this system to provide some snow
for the higher elevations such as Thompson Pass. Being that it is
early May, it becomes harder and harder to get significant
snowfall, but certainly not impossible. There are many variables
that need to come together to keep the precipitation from turning
over to rain, but we have introduced a healthy (5-10") of snow to
the coastal mountains with this package.

By Sun and Mon, the pattern starts to show two main features: a
building North American Ridge and a very broad, unseasonably deep
low over the Central Aleutians. The ridge will try to build up
from SE AK, but as it does so, it ushers in another shot of
moderate rain and wind for Prince William Sound and areas east.
By the middle of next week, all models are in fairly good
agreement that the Aleutian low will slide very near the Cold Bay
area. The trend has been to take this low slightly further south
and try to build some weak ridging over the mainland from the
Yukon Territory. However, for now, it looks to continue to be
mostly cloudy and slightly warmer for Southcentral with continued
wet along the Gulf Coast.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood Watch 155. Flood Advisory 152.
MARINE...Gale 132 150 155 170 172 173 174 179.

&&

SYNOPSIS AND MODEL DISCUSSION...DEK
SOUTHCENTRAL ALASKA...KH
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KVP
LONG TERM...MSO