Storm Warning 90, NWS Anchorage, AK

552 
FZAK52 PAFC 202316
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
316 PM AKDT Sun Sep 20 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.

PKZ199-211215-
316 PM AKDT Sun Sep 20 2020
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A 979 mb low at 55N 170W this afternoon will move into the Gulf 
Monday afternoon. 

$$

PKZ150-211215-
South of the AK Peninsula Sitkinak to Castle Cape-
316 PM AKDT Sun Sep 20 2020

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...SE wind 30 kt becoming S 15 kt W of Chirikof Island after
midnight. Seas 9 ft. Rain.
.MON...SE wind 30 kt, except variable 10 kt S of Chirikof Island. 
Seas 11 ft.
.MON NIGHT...NE wind 30 kt diminishing to 20 kt after midnight. S of
Chirikof Island, NE wind 15 kt. Seas 12 ft, subsiding to 8 ft near
the coast in the afternoon.
.TUE AND TUE NIGHT...N wind 35 kt. Seas 11 ft.
.WED...NW wind 30 kt. Seas 11 ft.
.THU...NW wind 25 kt. Seas 10 ft.
.FRI...NW wind 15 kt. Seas 8 ft.

$$

PKZ155-211215-
South of the AK Peninsula Castle Cape to Cape Sarichef-
316 PM AKDT Sun Sep 20 2020

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...S wind 25 kt diminishing to 15 kt after midnight. 
Seas 13 ft. Rain.
.MON...Variable wind 10 kt becoming N 20 kt in the afternoon. 
Seas 14 ft.
.MON NIGHT...N wind 25 kt. Seas 13 ft.
.TUE AND TUE NIGHT...NW wind 35 kt. Seas 12 ft.
.WED...NW wind 35 kt. Seas 11 ft.
.THU...NW wind 30 kt. Seas 10 ft.
.FRI...NW wind 15 kt. Seas 9 ft.

$$

PKZ160-211215-
Bristol Bay-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...E wind 35 kt. Seas 9 ft. Rain.
.MON...NE wind 35 kt diminishing to 25 kt in the afternoon. 
Seas 8 ft.
.MON NIGHT...NE wind 30 kt. Seas 7 ft.
.TUE...N wind 30 kt. Seas 7 ft.
.TUE NIGHT...N wind 25 kt. Seas 6 ft.
.WED...N wind 25 kt. Seas 6 ft.
.THU...NW wind 20 kt. Seas 5 ft.
.FRI...N wind 15 kt. Seas 3 ft.

$$

PKZ165-211215-
Port Heiden to Cape Sarichef-
316 PM AKDT Sun Sep 20 2020

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...S wind 15 kt in the evening becoming variable less 
than 10 kt. From Port Moller E, SE wind 30 kt. Seas 8 ft.
.MON...N wind 15 kt increasing to 25 kt in the afternoon. 
From Port Moller E, NE wind 30 kt. Seas 10 ft.
.MON NIGHT...N wind 25 kt. Seas 11 ft.
.TUE AND TUE NIGHT...NW wind 30 kt. Seas 11 ft.
.WED...NW wind 30 kt. Seas 10 ft.
.THU...NW wind 25 kt. Seas 8 ft.
.FRI...N wind 15 kt. Seas 7 ft.

$$

PKZ170-211215-
Cape Sarichef to Nikolski Bering Side-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING MONDAY AND MONDAY NIGHT...

.TONIGHT...SW wind 25 kt becoming N after midnight. From Dutch Harbor
E, SW wind 20 kt becoming N 15 kt after midnight. Seas 13 ft. Rain.
.MON...NW wind 35 kt. Seas 17 ft. Rain.
.MON NIGHT...NW wind 35 kt. Seas 16 ft. Rain.
.TUE...NW wind 30 kt. Seas 13 ft.
.TUE NIGHT...NW wind 25 kt. Seas 11 ft.
.WED THROUGH THU...NW wind 25 kt. Seas 9 ft.
.FRI...N wind 15 kt. Seas 8 ft.

$$

PKZ171-211215-
Unalaska Bay-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING MONDAY AND MONDAY NIGHT...

.TONIGHT...SW wind 10 kt becoming NW 15 kt after midnight. 
Seas 3 ft. Rain.
.MON...NW wind 20 kt increasing to 35 kt in the afternoon. 
Seas 7 ft building to 15 ft in the afternoon. Rain.
.MON NIGHT...NW wind 35 kt. Seas 15 ft. Rain.
.TUE...NW wind 30 kt. Seas 11 ft.
.TUE NIGHT...NW wind 25 kt. Seas 10 ft.
.WED...NW wind 25 kt. Seas 9 ft.
.THU...NW wind 15 kt. Seas 3 ft.
.FRI...N wind 10 kt. Seas 3 ft.

$$

PKZ172-211215-
Cape Sarichef to Nikolski Pacific Side-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING THROUGH MONDAY NIGHT...

.TONIGHT...SW wind 35 kt. From Dutch Harbor E, SW wind 25 kt
becoming NW 15 kt after midnight. Seas 20 ft. Rain.
.MON...NW wind increasing to 40 kt. Seas 18 ft.
.MON NIGHT...NW wind 40 kt. Seas 15 ft. Rain.
.TUE...NW wind 35 kt. Seas 12 ft.
.TUE NIGHT...NW wind 30 kt. Seas 10 ft.
.WED...NW wind 30 kt. Seas 9 ft.
.THU...NW wind 25 kt. Seas 7 ft.
.FRI...N wind 15 kt. Seas 9 ft.

$$

PKZ173-211215-
Nikolski to Seguam Island Bering Side-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...NW wind 40 kt. Seas 17 ft.
.MON...NW wind 40 kt diminishing to 30 kt in the afternoon. 
Seas 18 ft.
.MON NIGHT...NW wind 30 kt. Seas 14 ft.
.TUE...NW wind 30 kt. Seas 12 ft.
.TUE NIGHT...NW wind 20 kt. Seas 9 ft.
.WED...NW wind 20 kt. Seas 8 ft.
.THU THROUGH FRI...NW wind 15 kt. Seas 7 ft.

$$

PKZ174-211215-
Nikolski to Seguam Island Pacific Side-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...W wind 45 kt. Seas 27 ft.
.MON...NW wind 45 kt diminishing to 35 kt in the afternoon. 
Seas 22 ft.
.MON NIGHT...NW wind 30 kt. Seas 14 ft.
.TUE...NW wind 30 kt. Seas 11 ft.
.TUE NIGHT...NW wind 25 kt. Seas 8 ft.
.WED...NW wind 20 kt. Seas 7 ft.
.THU...SW wind 20 kt. Seas 8 ft.
.FRI...NW wind 20 kt. Seas 10 ft.

$$

PKZ175-211215-
Seguam Island to Adak Bering Side-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING TONIGHT...

.TONIGHT...NW wind 40 kt. Seas 19 ft.
.MON...NW wind 25 kt. Seas 15 ft.
.MON NIGHT...NW wind 20 kt. Seas 11 ft.
.TUE...NW wind 25 kt. Seas 9 ft.
.TUE NIGHT...NW wind 20 kt. Seas 8 ft.
.WED...NW wind 15 kt. Seas 6 ft.
.THU...NE wind 15 kt. Seas 6 ft.
.FRI...NW wind 20 kt. Seas 6 ft.

$$

PKZ176-211215-
Seguam Island to Adak Pacific Side-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...W wind 45 kt. Seas 27 ft.
.MON...NW wind 35 kt diminishing to 25 kt in the afternoon. Seas 16 
ft.
.MON NIGHT...NW wind 25 kt. Seas 9 ft.
.TUE...NW wind 25 kt. Seas 7 ft.
.TUE NIGHT...N wind 20 kt. Seas 6 ft.
.WED...N wind 15 kt. Seas 5 ft.
.THU...E wind 20 kt. Seas 8 ft.
.FRI...NW wind 20 kt. Seas 8 ft.

$$

PKZ177-211215-
Adak to Kiska-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING TONIGHT...

.TONIGHT...NW wind 40 kt diminishing to 30 kt after midnight. 
Seas 18 ft subsiding to 13 ft after midnight.
.MON...NW wind 25 kt diminishing to 15 kt in the afternoon. 
Seas 11 ft.
.MON NIGHT...NW wind 15 kt. Seas 8 ft.
.TUE AND TUE NIGHT...NE wind 15 kt. Seas 6 ft.
.WED...E wind 15 kt. Seas 6 ft.
.THU...N wind 20 kt. Seas 9 ft.
.FRI...W wind 25 kt. Seas 7 ft.

$$

PKZ178-211215-
Kiska to Attu-
316 PM AKDT Sun Sep 20 2020

...SMALL CRAFT ADVISORY THROUGH MONDAY...

.TONIGHT...NW wind 25 kt diminishing to 15 kt after midnight. 
Seas 12 ft.
.MON...Variable wind 10 kt. Seas 8 ft.
.MON NIGHT...Variable wind 10 kt. Seas 7 ft.
.TUE AND TUE NIGHT...E wind 15 kt. Seas 6 ft.
.WED...E wind 15 kt. Seas 7 ft.
.THU...NW wind 20 kt. Seas 10 ft.
.FRI...W wind 25 kt. Seas 8 ft.

$$

PKZ179-211215-
Pribilof Islands Near Shore Waters-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...NE wind 35 kt. Seas 15 ft.
.MON...N wind 35 kt. Seas 14 ft.
.MON NIGHT...NW wind 30 kt. Seas 11 ft.
.TUE AND TUE NIGHT...NW wind 25 kt. Seas 9 ft.
.WED...NW wind 20 kt. Seas 7 ft.
.THU...NW wind 15 kt. Seas 6 ft.
.FRI...Variable wind 10 kt. Seas 7 ft.

$$

PKZ180-211215-
Kuskokwim Delta and Etolin Strait-
316 PM AKDT Sun Sep 20 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...E wind 35 kt. Seas 11 ft. Rain.
.MON...NE wind 35 kt diminishing to 25 kt in the afternoon. Seas
11 ft.
.MON NIGHT...NE wind 25 kt. Seas 7 ft.
.TUE AND TUE NIGHT...N wind 30 kt. Seas 8 ft.
.WED...N wind 30 kt. Seas 8 ft.
.THU...NW wind 25 kt. Seas 6 ft.
.FRI...N wind 15 kt. Seas 5 ft.

$$

PKZ181-211215-
North and West of Nunivak Island-
316 PM AKDT Sun Sep 20 2020

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...NE wind 25 kt. Seas 8 ft.
.MON...N wind 25 kt. Seas 8 ft.
.MON NIGHT...N wind 25 kt. Seas 8 ft.
.TUE AND TUE NIGHT...N wind 25 kt. Seas 7 ft.
.WED...N wind 25 kt. Seas 6 ft.
.THU THROUGH FRI...N wind 20 kt. Seas 6 ft.

$$

PKZ185-211215-
Saint Matthew Island Waters-
316 PM AKDT Sun Sep 20 2020

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...NE wind 30 kt. Seas 12 ft.
.MON...N wind 30 kt E of Saint Matthew Island...N 20 kt W of Saint
Matthew Island. Seas 10 ft.
.MON NIGHT...N wind 25 kt. Seas 8 ft.
.TUE AND TUE NIGHT...NW wind 20 kt. Seas 6 ft.
.WED THROUGH THU...N wind 20 kt. Seas 5 ft.
.FRI...N wind 25 kt. Seas 6 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
431 PM AKDT Sat Sep 19 2020

.ANALYSIS AND UPPER LEVELS...

A shortwave ridge axis extends from the north Pacific, through
southwest Alaska, up through the center part of the state. This is
in between a trough that extends from eastern Siberia through the
central Aleutians, and an area of low pressure across the
southern Gulf. Area radar imagery shows showers with this low
moving northward through the Gulf Coast, with other showers trying
to move into coastal locations of southwest Alaska as the
aforementioned ridge breaks down.

&&

.MODEL DISCUSSION...

The models are generally in good agreement at the surface and
aloft over the next few days, leading to higher than average
forecast confidence.

&&

.AVIATION...

PANC...VFR conditions along with southerly winds occasionally
gusting into the 20 to 25 knot range will persist through this
evening. MVFR ceilings are possible after 8z due to an increase in
shower activity around the terminal. There is also some indication
in the forecast guidance that IFR ceilings may develop over the
terminal after 14z. Confidence in this is low, however, and is
currently not included in the current TAF package.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Sat
afternoon through Tue afternoon)...

An upper level trough to our west will move in this evening,
bringing increasing chances for rain across Southcentral. The
greatest amount of precipitation will be along the northern Gulf
coast and the eastern Kenai Peninsula. There are some showers
lifting northward this afternoon over Prince William Sound and
across the Susitna Valley, but as this trough moves in, rain is
expected to become more widespread. Sunrise on Sunday morning may
reveal sights of termination dust across the higher elevations of
the Chugach and Talkeetna Mountains, as cooler temperatures aloft
allow for overnight precipitation to fall as snow.

As the trough exits to the north Sunday afternoon, conditions
should generally improve over the Susitna Valley, western Kenai
Peninsula, and Anchorage Bowl, though a stray mountain shower
cannot be ruled out. Additional rainfall is likely for the Prince
William Sound area as well as across the Copper River Basin
through Sunday night.

By Monday, the attention shifts westward, where a large low
developing over the Bering moves toward the southeast and lifts a
front across Kodiak Island early Monday. Abundant moisture and
gusty easterly winds are likely, with gale force winds expected
along the extent of this front across the Gulf waters. While the
low center remains well south of Southcentral over the Gulf, the
associated front will bring gusty winds and rain to the northern
Gulf coast as it lifts northward Tuesday morning. Once again, the
bulk of precipitation is expected to fall across Kodiak Island and
the northern Gulf coast, while interior areas of Southcentral
including the Susitna Valley and northern Copper River Basin
should remain relatively dry through Tuesday.

&&

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

Generally quiet conditions are expected through the weekend. Weak
shortwave troughs are currently producing isolated showers across
portions of the Kuskokwim Delta and Bristol Bay. These will
gradually taper off overnight under a weak upper level ridge.
Combined with weak southerly flow, patchy fog and/or low stratus
is possible near the Kuskokwim Delta coast. A similar pattern is
expected for Sunday with weak shortwaves propagating over
Southwest Alaska bringing isolated showers. A front associated
with a low over the eastern Aleutians will bring gusty easterly
winds to much of the region by Monday. As such, conditions will
remain dry in the lee of the Alaska Range and temperatures will
drop slightly, with lows well into the 30s over interior areas.

&&

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

A broad low will move southeast across the Bering through the
weekend. Its associated front will bring steady rain and gusty
southerly winds across the Aleutians, while strong northwesterly
winds and showers will develop on its backside. Cold air
advection is starting to become more robust as the fall season
approaches. The low will become vertically stacked near Unalaska
on Sunday evening, thereby weakening. A cool, northwesterly flow
will develop is its wake ahead of a developing ridge over the
western Bering. Thus, showers will continue through early next
week.

&&

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

Gulf of Alaska: A broad and strong storm system is expected to
remain nearly stationary and weaken over the southern Gulf through
Thursday. There is high confidence in Gale force winds over the
northern Gulf coast with potential for storm force gusts if a
secondary low is to develop in the lee of Kodiak Island on Tue. By
late Wednesday night the low is expected to weaken, which will
bring winds down to at or below small craft criteria.

Bering Sea/Aleutian Islands: There is high confidence that the
broad low pressure system over the Gulf will bring moderate to
strong northerly winds over the eastern Bering. The winds will be
strongest (gale force) through the terrain gaps from Nikolski to
Sand Point through Thursday morning. By this time winds should
calm down to well below gale criteria as the low to the east
breaks down. Over the western Bering, there is high confidence
that high pressure and calm winds are expected to persist through
Wed night. On Thursday confidence decreases significantly in
regards to the next system, with models showing a 20 mb spread.
If the stronger solutions comes to fruition, gale force winds are
possible moving east across the Aleutian Chain Thursday night into
Friday.

&&

.LONG TERM FORECAST (Days 4 through 7/Wednesday through
Saturday)...

A broad and strong low pressure system is expected to be centered
over the Gulf at the start of the forecast period. The main impact
from this system will be for the Gulf coast and Kodiak Island,
where strong winds and rain are expected to persist through
Wednesday afternoon. For Southcentral it should be mostly dry,
with seasonal temperatures and the occasional shower as weak
shortwaves move around the low center. On the backside of the
low, strong winds and increasingly cool, northerly wind are
expected to persist over the eastern Bering and coastal areas of
Southwest through Thursday night. By Friday morning, an arctic
trough is expected to move in from the Bering Strait, which will
cool off the Bering considerably through Saturday.

The main forecast question is in regards to the next system
forecast to move over/near the central Aleutians Thursday night.
Forecast confidence decreases considerably due to a large model
spread in both the location and strength of this system. The GFS
and Canadian models have a storm force low clipping the central
Aleutians on Friday as it rapidly moves east into the Gulf by
Saturday morning. The primary difference between these solutions
and the EC, which has a considerably weaker system, is whether or
not jet remains zonal or becomes slightly meridional. If the jet
is to become meridional, then the storm will have a better chance
of tapping into the strong temperature gradient N/S of the
Aleutian Chain to produce a stronger storm. Regardless, model
agreement and forecast confidence increases once again Saturday, with
a strong system moving into the Gulf.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 160 172-175 177 179 411-414.
Storm Warning 176 178.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...KO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...CJ