Gale Warning 405, NWS Anchorage, AK

578 
FZAK62 PAFC 141211
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
411 AM AKDT Thu Sep 14 2017

Offshore Waters Forecast for the Bering Sea

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.

PKZ499-150115-
411 AM AKDT Thu Sep 14 2017
.SYNOPSIS FOR CENTRAL BERING SEA...
A 990 mb North Pacific low deepens to 985 mb as it crosses over
Amchitka this afternoon then strengthens to 971 mb as it moves
near Saint Paul Friday afternoon. This low quickly moves southeast
to near 57N 163W at 975 mb late Friday night.

$$

PKZ411-150115-
Bering Sea Offshore West of 180 and East of the International
Dateline-
411 AM AKDT Thu Sep 14 2017

.TODAY...N wind 10 to 20 kt. Seas 4 ft.
.TONIGHT...NW wind 15 to 25 kt. Seas 3 to 6 ft.
.FRI...NW wind 15 to 25 kt. Seas 6 to 10 ft.
.FRI NIGHT...W wind 15 to 25 kt. Seas 7 to 10 ft.
.SAT...W wind up to 20 kt. Seas 4 to 9 ft.
.SUN...N wind up to 20 kt. Seas 3 to 6 ft.
.MON...W wind up to 20 kt. Seas 3 to 7 ft.

$$

PKZ412-150115-
Bering Sea Offshore 171W to 180 and North of 56N-
411 AM AKDT Thu Sep 14 2017

...STORM WARNING FRIDAY...

.TODAY...S wind 15 to 25 kt except variable 15 kt W of 176w . Seas 4
to 8 ft.
.TONIGHT...E to N wind 20 to 35 kt. Seas 6 to 11 ft. Rain.
.FRI...NW wind 35 to 50 kt. Seas 12 to 20 ft. Rain.
.FRI NIGHT...NW wind 30 to 45 kt. Seas 13 to 21 ft.
.SAT...W wind 15 to 30 kt. Seas 9 to 17 ft.
.SUN...SE wind up to 15 kt. Seas 4 to 7 ft.
.MON...N wind up to 15 kt. Seas 3 to 7 ft.

$$

PKZ413-150115-
Bering Sea Offshore 171W to 180 and South of 56N-
411 AM AKDT Thu Sep 14 2017

...STORM WARNING FRIDAY...

.TODAY...S wind up to 20 kt becoming SE 15 to 30 kt in the
afternoon. Seas 4 to 9 ft. Rain.
.TONIGHT...SE wind 20 to 35 kt becoming NW 25 to 40 kt after
midnight. Seas 7 to 12 ft. Rain.
.FRI...NW wind 35 to 50 kt. Seas 13 to 21 ft building to 15 to 30 ft
in the afternoon.
.FRI NIGHT...W wind 25 to 40 kt. Seas 13 to 21 ft.
.SAT...W wind 15 to 30 kt. Seas 9 to 17 ft.
.SUN...E wind up to 20 kt. Seas 5 to 9 ft.
.MON...N wind 10 to 20 kt. Seas 4 to 8 ft.

$$

PKZ414-150115-
Bering Sea Offshore East of 171W-
411 AM AKDT Thu Sep 14 2017

...STORM WARNING FRIDAY...

.TODAY...W wind up to 15 kt becoming S 10 to 25 kt in the
afternoon. Seas 5 ft.
.TONIGHT...SE wind 20 to 35 kt. Seas 5 to 10 ft. Rain.
.FRI...SE wind 25 to 40 kt becoming W 40 to 55 kt in the afternoon. 
Seas 9 to 14 ft building to 16 to 30 ft in the afternoon. Rain.
.FRI NIGHT...NW wind 40 to 55 kt. Seas 16 to 31 ft.
.SAT...NW wind 30 to 45 kt. Seas 15 to 23 ft.
.SUN...S wind 10 to 25 kt. Seas 6 to 10 ft.
.MON...NE wind up to 15 kt. Seas 4 to 7 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
532 AM AKDT Wed Sep 13 2017

.ANALYSIS AND UPPER LEVELS...

The upper level pattern features a ridge over the Yukon Territory
and SE Alaska. Upstream there is a vortex over the NE Russia and
the Bering Sea and widespread southwest flow from Kodiak to the
Brooks Range. The latest infrared satellite image depicts a
frontal boundary with a cloud shield spanning from the north slope
to the Alaska Peninsula and the tail end of the cold front
spanning into the North Pacific. A tight pressure gradient has set
up from southcentral to the AK Peninsula. The radar at King Salmon
and Kenai are both pinging into precipitation activity.

&&

.MODEL DISCUSSION...
Models are in good agreement with the major features of the long
wave pattern through 48 hrs. The run to run consistency in the
short term continues this model cycle. This forecast package
hedged towards the higher resolution models which depict more more
realistic local terrain gap winds. Past 48 hrs, the NCEP Relative
Measure Of Predictability for the Ensemble Mean radically
transitions to low confidence territory in association with the
longwave trough moving towards the mainland.

&&

.AVIATION...
PANC...VFR conditions will persist. With a tight pressure gradient
in place, gusty winds expected to continue today.

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

Radar this morning indicates some light rain showers scattered
across southern portions of the Southcentral mainland. However,
further to the southwest near the front, radar indicates a much
more solid swath of rain. As this front slowly pushes eastward
today, the ridge to the east will remain well in place across the
eastern Gulf of Alaska. As a result, pressure gradients will
tighten and continue to support cross-barrier and southeasterly
flow. As the front slowly approaches, rain will increase today
into tonight across the upslope regions of the eastern Kenai
Peninsula, Prince William Sound and Susitna Valley. In contrast,
downsloping will maintain its hold across the Anchorage Bowl,
western Kenai Peninsula and Matanuska Valley. This pattern will
remain locked in place into Wednesday as the ridge maintains its
position. However, by Thursday the front will finally push
eastward into the Gulf of Alaska.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Steady rain will continue for the Bristol Bay area, and to a
lesser extent, the Kuskokwim Valley. For the Kuskokwim Delta area,
rain will stay scattered in nature. The disturbance responsible
for the rain today will move northward out of the area late this
afternoon, but areas of rain will continue through Thursday as the
longwave trough remains over the Mainland. Thursday evening the
pattern begins to change as a very fall-like system takes shape in
the Bering Sea. The strong low pressure system will bring a front
to the mainland on Friday morning and begin to increase winds out
of the southeast.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A couple of weak lingering troughs will keep showers and areas of
rain across the Bering, but the real story is a developing fall
system for Thursday. A rapidly developing cyclone will bring
gale-force winds on the front side of the system to the central
Bering Sea. As the system reaches peak intensity on Friday
morning, winds on the backside of the system will ramp up with
potentially hurricane-force gusts. The exact track of the system
will determine where the highest swath of winds tracks, but the
Pribilof Islands will be close. Stay tuned to the forecast.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The long term pattern will continue to be active with several
systems moving through the region by the middle of next week. On
Friday, a departing weak surface trough will lead to lingering
rain along the North Gulf Coast. This system will be kicked out of
the area as a strong cyclone forms in the Central Bering Sea,
which will be the main focus of the period. Models are in decent
agreement regarding the early track of the storm, with the low
center deepening to about 970 mb as it moves NE towards the
Pribilofs. Models begin to diverge by Friday night, with the
EC/NAM being more progressive taking the center directly over the
Pribilofs then SE across the AKPEN into the Gulf. The GFS takes
the low just north of the Pribilofs then becomes quasi-stationary
just offshore of the Seward Peninsula, which seems to be the
outlier among the models. Regardless of the exact position, a
very tight pressure gradient combined with cold air advection on
the backside of the low will lead to storm force winds across the
Central and Southern Bering, including the Pribilof Islands, on
Friday and Saturday. The low looks to move into the Gulf by Sunday
bringing good chances of strong winds and heavy rain to coastal
communities over the weekend. A some what quieter pattern looks to
develop early next week as a weaker storm brushes the Aleutians
and high pressure tries to build into the Western Bering by
Tuesday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gales 173 174 175 176 177.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PJS
SOUTHCENTRAL ALASKA...ELN
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML
LONG TERM...KVP

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
114 PM AKDT Wed Sep 13 2017

AKZ195-141430-
Pribilof Islands-
Including the city of Saint Paul
114 PM AKDT Wed Sep 13 2017

...Developing fall storm could bring first big wind of the season
to the Pribilof Islands...

We are monitoring the development of a seasonably strong low
pressure system that will begin to impact the Bering Sea on
Thursday. Currently the system looks to reach peak intensity
around or just east of the Pribilof Islands on Friday afternoon
which could bring northwest wind gusts as high as 65 MPH. The
swath of the strongest winds will be highly sensitive to the exact
storm track and is still subject to change. Stay tuned to the
forecast for further information.