Gale Warning 533, NWS Anchorage, AK

006 
FZAK52 PAFC 222310
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
310 PM AKDT Sun Oct 22 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.

PKZ199-231215-
310 PM AKDT Sun Oct 22 2017
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...
A 994 mb low along the Y-K Delta coast will weaken into a trough 
of low pressure through Mon night. A compact 996 mb low 110 nm 
southwest of Sand Point will move inland and weaken across 
Bristol Bay Mon morning. A West Pacific low will rapidly deepen 
and move into the western Bering Sea Mon morning then peak in 
intensity at 938 mb 230 nm west of Shemya Tue morning. 

$$

PKZ150-231215-
South of the AK Peninsula Sitkinak to Castle Cape-
310 PM AKDT Sun Oct 22 2017

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...SE wind 30 kt becoming NW 20 kt after midnight. 
Seas 9 ft.
.MON...W wind 15 kt. Seas 6 ft.
.MON NIGHT...SW wind 15 kt. Seas 5 ft.
.TUE...W wind 25 kt. Seas 8 ft.
.TUE NIGHT...S wind 45 kt. Seas 22 ft.
.WED...S wind 40 kt. Seas 22 ft.
.THU THROUGH FRI...SW wind 20 kt. Seas 15 ft.

$$

PKZ155-231215-
South of the AK Peninsula Castle Cape to Cape Sarichef-
310 PM AKDT Sun Oct 22 2017

.TONIGHT...W wind 15 kt. Seas 6 ft.
.MON...W wind 15 kt. Seas 4 ft.
.MON NIGHT...W wind 15 kt. Seas 4 ft.
.TUE...S wind 50 kt. Seas 16 ft.
.TUE NIGHT...S wind 45 kt. Seas 23 ft.
.WED THROUGH THU...SW wind 30 kt. Seas 22 ft.
.FRI...SW wind 25 kt. Seas 15 ft.

$$

PKZ160-231215-
Bristol Bay-
310 PM AKDT Sun Oct 22 2017

.TONIGHT...SW wind 10 kt. Seas 4 ft.
.MON...W wind 15 kt. Seas 4 ft.
.MON NIGHT...SW wind 15 kt. Seas 4 ft.
.TUE...S wind 25 kt. Seas 5 ft.
.TUE NIGHT...SE wind 40 kt. Seas 11 ft.
.WED...S wind 30 kt. Seas 9 ft.
.THU...S wind 25 kt. Seas 9 ft.
.FRI...S wind 20 kt. Seas 9 ft.

$$

PKZ165-231215-
Port Heiden to Cape Sarichef-
310 PM AKDT Sun Oct 22 2017

.TONIGHT...W wind 15 kt. Seas 6 ft.
.MON...W wind 15 kt. Seas 6 ft.
.MON NIGHT...SW wind 20 kt. Seas 6 ft.
.TUE...S wind 50 kt. Seas 12 ft.
.TUE NIGHT...S wind 45 kt. Seas 14 ft.
.WED...S wind 30 kt. Seas 13 ft.
.THU THROUGH FRI...SW wind 30 kt. Seas 13 ft.

$$

PKZ170-231215-
Cape Sarichef to Nikolski Bering Side-
310 PM AKDT Sun Oct 22 2017

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

.TONIGHT...NW wind 20 kt. Seas 8 ft.
.MON...NW wind 15 kt. Seas 8 ft.
.MON NIGHT...SW wind 15 kt becoming S 30 kt after midnight. 
Seas 8 ft.
.TUE...S wind 50 kt. Seas 17 ft.
.TUE NIGHT...S wind 30 kt. Seas 16 ft.
.WED...S wind 40 kt. Seas 17 ft.
.THU THROUGH FRI...SW wind 30 kt. Seas 14 ft.

$$

PKZ171-231215-
Unalaska Bay-
310 PM AKDT Sun Oct 22 2017

.TONIGHT...NW wind 10 kt. Seas 3 ft.
.MON...NW wind 15 kt becoming W in the afternoon. Seas 5 ft.
.MON NIGHT...SW wind 10 kt becoming S 20 kt after midnight. 
Seas 5 ft.
.TUE...S wind 45 kt. Seas 6 ft.
.TUE NIGHT...S wind 25 kt. Seas 3 ft.
.WED...S wind 30 kt. Seas 4 ft.
.THU THROUGH FRI...S wind 20 kt. Seas 3 ft.

$$

PKZ172-231215-
Cape Sarichef to Nikolski Pacific Side-
310 PM AKDT Sun Oct 22 2017

...SMALL CRAFT ADVISORY MONDAY NIGHT...

.TONIGHT...NW wind 20 kt. Seas 5 ft.
.MON...NW wind 15 kt. Seas 5 ft.
.MON NIGHT...W wind 20 kt becoming S 30 kt after midnight. 
Seas 6  ft building to 9 ft after midnight. Rain.
.TUE...S wind 50 kt. Seas 22 ft.
.TUE NIGHT...SW wind 30 kt. Seas 23 ft.
.WED...S wind 40 kt. Seas 32 ft.
.THU...SW wind 30 kt. Seas 27 ft.
.FRI...SW wind 25 kt. Seas 15 ft.

$$

PKZ173-231215-
Nikloski to Seguam Island Bering Side-
310 PM AKDT Sun Oct 22 2017

...STORM WARNING MONDAY NIGHT...

.TONIGHT...NW wind 25 kt. Seas 10 ft.
.MON...NW wind 20 kt in the morning becoming W 10 kt. Seas 10 ft.
.MON NIGHT...W wind 25 kt becoming SE 50 kt after midnight. 
Seas 10 ft building to 18 ft after midnight. Rain.
.TUE...S wind 55 kt. Seas 20 ft.
.TUE NIGHT...S wind 35 kt. Seas 20 ft.
.WED...SW wind 40 kt. Seas 21 ft.
.THU...SW wind 30 kt. Seas 17 ft.
.FRI...SW wind 25 kt. Seas 13 ft.

$$

PKZ174-231215-
Nikolski to Seguam Island Pacific Side-
310 PM AKDT Sun Oct 22 2017

...STORM WARNING MONDAY NIGHT...

.TONIGHT...NW wind 25 kt. Seas 9 ft.
.MON...NW wind 20 kt. Seas 9 ft.
.MON NIGHT...W wind 20 kt becoming S 50 kt after midnight. 
Seas 10 ft building to 18 ft after midnight. Rain.
.TUE...S wind 55 kt. Seas 23 ft.
.TUE NIGHT...SW wind 40 kt. Seas 31 ft.
.WED...SW wind 45 kt. Seas 39 ft.
.THU...SW wind 30 kt. Seas 26 ft.
.FRI...SW wind 25 kt. Seas 14 ft.

$$

PKZ175-231215-
Seguam Island to Adak Bering Side-
310 PM AKDT Sun Oct 22 2017

...STORM WARNING MONDAY NIGHT...

.TONIGHT...NW wind 25 kt. Seas 12 ft. Snow showers.
.MON...NW wind 20 kt becoming SW in the afternoon. Seas 11 ft.
.MON NIGHT...S wind 40 kt becoming SE 55 kt after midnight. 
Gusts to 70 kt after midnight. Seas 9 ft building to 19 ft 
after midnight. Rain and snow.
.TUE...SW wind 55 kt. Seas 20 ft.
.TUE NIGHT...S wind 40 kt. Seas 21 ft.
.WED...W wind 35 kt. Seas 19 ft.
.THU...SW wind 30 kt. Seas 14 ft.
.FRI...SW wind 25 kt. Seas 13 ft.

$$

PKZ176-231215-
Seguam Island to Adak Pacific Side-
310 PM AKDT Sun Oct 22 2017

...STORM WARNING MONDAY NIGHT...

.TONIGHT...NW wind 30 kt. Seas 10 ft.
.MON...NW wind 20 kt. Seas 8 ft.
.MON NIGHT...S wind 45 kt increasing to 55 kt after midnight. 
Gusts to 70 kt after midnight. Seas 10 ft building to 23 ft 
after midnight. Rain and snow.
.TUE...SW wind 55 kt. Seas 33 ft.
.TUE NIGHT...SW wind 50 kt. Seas 43 ft.
.WED...W wind 45 kt. Seas 43 ft.
.THU...SW wind 30 kt. Seas 23 ft.
.FRI...SW wind 25 kt. Seas 15 ft.

$$

PKZ177-231215-
Adak to Kiska-
310 PM AKDT Sun Oct 22 2017

...STORM WARNING MONDAY NIGHT...

.TONIGHT...NW wind 25 kt. Seas 13 ft.
.MON...W wind 20 kt becoming S 45 kt in the afternoon. 
Seas 9 ft. Snow and rain.
.MON NIGHT...SE wind 55 kt. Gusts to 70 kt. Seas 23 ft. Rain.
.TUE AND TUE NIGHT...SW wind 45 kt. Seas 42 ft.
.WED...NW wind 40 kt. Seas 40 ft.
.THU...SW wind 30 kt. Seas 17 ft.
.FRI...SW wind 25 kt. Seas 16 ft.

$$

PKZ178-231215-
Kiska to Attu-
310 PM AKDT Sun Oct 22 2017

...STORM WARNING MONDAY AND MONDAY NIGHT...

.TONIGHT...SW wind 25 kt. Seas 10 ft. Rain.
.MON...SE wind 45 kt increasing to 55 kt in the afternoon. 
Gusts to 70 kt in the afternoon. Seas 11 ft building to 20 ft 
in the afternoon. Rain and snow.
.MON NIGHT...S wind 55 kt. Gusts to 70 kt in the evening. 
Seas 27 ft. Rain.
.TUE...SW wind 50 kt. Seas 44 ft.
.TUE NIGHT...N wind 40 kt. Seas 40 ft.
.WED...NW wind 40 kt. Seas 33 ft.
.THU...W wind 30 kt. Seas 18 ft.
.FRI...W wind 25 kt. Seas 18 ft.

$$

PKZ179-231215-
Pribilof Islands Near Shore Waters-
310 PM AKDT Sun Oct 22 2017

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

.TONIGHT...NW wind 20 kt. Seas 8 ft.
.MON...NW wind 20 kt. Seas 8 ft.
.MON NIGHT...Variable wind 10 kt becoming S 25 kt after midnight. 
Seas 7 ft.
.TUE...SE wind 50 kt. Seas 19 ft.
.TUE NIGHT...S wind 30 kt. Seas 20 ft.
.WED...S wind 25 kt. Seas 18 ft.
.THU THROUGH FRI...SW wind 30 kt. Seas 12 ft.

$$

PKZ180-231215-
Kuskokwim Delta and Etolin Strait-
310 PM AKDT Sun Oct 22 2017

.TONIGHT...NW wind 15 kt. Seas 5 ft.
.MON...W wind 15 kt. Seas 5 ft.
.MON NIGHT...SW wind 20 kt. Seas 4 ft.
.TUE...S wind 35 kt. Seas 8 ft.
.TUE NIGHT...SE wind 45 kt. Seas 15 ft.
.WED THROUGH FRI...SW wind 30 kt. Seas 12 ft.

$$

PKZ181-231215-
North and West of Nunivak Island-
310 PM AKDT Sun Oct 22 2017

.TONIGHT...N wind 20 kt. Seas 7 ft.
.MON...N wind 10 kt. Seas 5 ft.
.MON NIGHT...N wind 10 kt. Seas 5 ft.
.TUE...SE wind 35 kt. Seas 6 ft.
.TUE NIGHT...E wind 45 kt. Seas 14 ft.
.WED...SE wind 35 kt. Seas 13 ft.
.THU THROUGH FRI...S wind 25 kt. Seas 9 ft.

$$

PKZ185-231215-
Saint Matthew Island Waters-
310 PM AKDT Sun Oct 22 2017

...GALE WARNING MONDAY NIGHT...

.TONIGHT...NW wind 20 kt E of Saint Matthew Island...NW 30 kt 
W of Saint Matthew Island. Seas 11 ft.
.MON...N wind 20 kt. Seas 9 ft.
.MON NIGHT...E of Saint Matthew Island, E wind 15 kt. W of Saint
Matthew Island, E wind 25 kt increasing to 35 kt after midnight.
Seas 6 ft building to 10 ft after midnight.
.TUE...E wind 50 kt. Seas 18 ft.
.TUE NIGHT...NE wind 50 kt. Seas 25 ft.
.WED...NE wind 45 kt. Seas 25 ft.
.THU...NW wind 20 kt. Seas 12 ft.
.FRI...SW wind 20 kt. Seas 11 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
422 PM AKDT Sat Oct 21 2017

.ANALYSIS AND UPPER LEVELS...
Satellite imagery this afternoon depicts a very well defined NPAC
jet stream stretching from Japan to the west coast of Washington.
A cold upper level arctic trough is centered over the Y-K Delta
with cold arctic air spilling out over the Bering Sea into the
North Pacific. A complex surface low is moving inland across the
Southeast panhandle with this system representing the leading edge
of the NPAC jet stream. Closer to home, weak southerly flow aloft
is bringing in higher values of potential vorticity aloft which
is helping to create a broad area of upper level ascent over
Southcentral. This is helping to create an area of convectively
enhanced showers over the North Gulf Coast and Prince William
Sound. These showers have been moving inland across Portage/Whittier
and west into Turnagain Arm and Pass...and even into the
Anchorage Bowl. Snow showers are also impacting the coast of the
Kuskokwim Delta in association with the arctic trough.

&&

.MODEL DISCUSSION...
The models are in overall good agreement with the large scale
pattern late into next week, and are generally pretty locked into
a deep upper 930 hpa low over the Bering Sea as the remnants of
Typhoon Lan phase with an extratropical low. However, the models
are in very poor agreement with a series of small scale embedded
shortwave troughs features lifting north along the trough axis
embedded within the low level cold air. The first of these systems
is expected to move into Bristol Bay and north into the Lower
Kuskokwim Valley Sunday night into Monday morning. The ECMWF and
Canadian are both faster than the stronger NAM and GFS solutions.
For this forecast, the GFS was favored for that low followed by a
blended ECMWF and GFS approach as it moves east into Southcentral
Monday evening.

Finally, another low is expected to move up toward the coast
Tuesday morning and afternoon. The GFS and ECMWF are both in good
agreement, however, with this pattern of low amplitude lows moving
north, confidence remains rather low at this point even with
agreement among the global models. For now, this forecast will
highlight increasing snow chances along the coast with chance snow
threats for inland locales.

&&

.AVIATION...
PANC...Light snow this afternoon/evening will drop ceilings to
near 3000 feet along with brief MVFR visibility reductions before
snow ends late this evening. Another weak low will clip the area
Sunday afternoon, bringing a slight chance for snow showers to the
terminal. Winds are expected to remain below 10 knots.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Anchorage's first official measurable snow of the 2017-2018 snow
season occurred this afternoon. A wave moving through around a
strong, cold upper level low centered near Hooper Bay tracked up
the Inlet. As it gathered moisture from a weak surface low over
Prince William Sound, the snow moved down Turnagain Arm and into
Anchorage. As the wave and associated lift move northward tonight,
the light snow activity will gradually shift into the Matanuska
and Susitna Valleys this evening through the first half of the
night, then dissipate before sunrise.

The pattern of weak waves moving northward into Southcentral
continues on Sunday as a second wave moves northeastward from
south of Kodiak Island Sunday morning into Prince William Sound,
then dissipates as it moves into the eastern Copper River Basin
Sunday night. Another round of snow is possible with this wave,
particularly for Valdez, Cordova, and the southern Copper River
Basin Sunday afternoon and evening, where a couple inches could
accumulate.

The third wave in the train moves into Kodiak on Monday morning,
bringing with it more cold air, so snow is the expected
precipitation type there. As it lifts northward, it will interact
with a separate wave tracking northward through the central Gulf.
The details of how this interaction takes place are still very
unclear and vary between the models, but generally speaking snow
is possible along portions of the Gulf Coast Monday afternoon,
with some potential it may spread inland beyond that. Stay tuned.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
Low pressure along the Kuskokwim Delta remains nearly stationary
through Sunday then merges with a fast moving low which races
north across the Alaska Peninsula to the Kuskokwim Sunday night
into Monday. At the Same time, an anchored upper level low along
Nunivak Island will swing short waves along the southwest mainland
which keeps snow showers ongoing through Tuesday. The highest
chances for snow on Sunday are expected along the coasts of
Kuskokwim Delta and Bristol Bay as new energy glides around the
low from the Bering Strait. The focus for the highest snow
accumulations will be along the low that races in from the
North Pacific, therefore increased snow chances along the eastern
Alaska Peninsula, eastern areas of Bristol Bay and along the
western Alaska Range Sunday night into Monday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
Low pressure along the eastern Bering will bring widespread snow
showers through the weekend with a mix of snow and rain along the
Alaska Peninsula and Aleutian chain. The main forecast challenge
surrounds the extratropical system Lan, which moves a front into
the western Aleutians Sunday night. Heavy rain and max storm force
gusts are expected along the frontal boundary which moves north
and east to the northern and central Bering through Tuesday. This
system will occlude late Monday night with the surface low rapidly
deepening along the western Aleutians on Tuesday. There is still
uncertainty on the strength and tracking of this system and should
be monitored for updates.

&&

.LONG TERM FORECAST (Days 3 through 7)...
An active pattern is expected to evolve during the long range
forecast through the middle of next week, with the focus being on
the remnants of Typhoon Lan entering the Bering and upper level
disturbances over the Gulf tracking into Southcentral.

The moisture rich and storm force remnants of Typhoon Lan will
push into the western Aleutians/Bering Monday evening in the form
of a warm front, also bringing some warmer temperatures and rain
to the area through mid-week. Models remain in good agreement up
until this point, but confidence begins to wane as the models
begin struggling more with the track and timing of the system
central and eastern Bering through Thursday. This leads to lower
confidence on the timing, placement, and strength of any potential
wind threats and precipitation over the Aleutians and Bering as
the leading front passes through. This system will eventually
spread gusty winds and rain/snow over the southern Mainland
Wednesday morning through the end of the week.

The other features we are monitoring are a series of upper level
waves tracking through the Gulf and into Southcentral Monday
evening through Wednesday. Given the cold air already in place
over the area, these waves bring potential for snow to make it
into Southcentral, with potential for moderate to heavy snowfall
along the Northern Gulf coast, Susitna Valley, and Copper river
Basin areas. The only caveat to that is that the models are
struggling with where and when these smaller systems develop and
when they eventually track.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

SYNOPSIS AND MODEL DISCUSSION...JA
SOUTHCENTRAL ALASKA...JW
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KH
LONG TERM...TP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
152 AM AKDT SUN OCT 22 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0406 PM     SNOW             1 ESE POTTER MARSH      61.05N 149.77W
10/21/2017  M1.9 INCH                           AK   TRAINED SPOTTER

0733 PM     SNOW             1 N RABBIT CREEK        61.10N 149.82W
10/21/2017  M1.5 INCH                           AK   NWS EMPLOYEE

0753 PM     SNOW             2 NNW GLEN ALPS         61.12N 149.71W
10/21/2017  M3.0 INCH                           AK   TRAINED SPOTTER

            NEAR OMALLEY TRAILHEAD, 1400 FEET ELEVATION

&&

KO