Hurricane Force Wind Warning 6, NWS Anchorage, AK

329 
FZAK62 PAFC 161159
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
359 AM AKDT Sat Sep 16 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.

PKZ499-170030-
359 AM AKDT Sat Sep 16 2017
.SYNOPSIS FOR CENTRAL BERING SEA...

A 975 mb low near 57N 165W moves to 57N 159W at 982 mb Sat 
afternoon...then moves into the Gulf. A North Pacific front 
approaches the western and central Aleutians Sat night through Sun
afternoon.

$$

PKZ411-170030-
Bering Sea Offshore West of 180 and East of the International
Dateline-
359 AM AKDT Sat Sep 16 2017

.TODAY...W wind 10 to 20 kt. Seas 6 to 10 ft.
.TONIGHT...NW wind up to 15 kt. Seas 4 to 8 ft.
.SUN...N wind 10 to 15 kt. Seas 5 ft.
.SUN NIGHT...NW wind up to 15 kt. Seas 3 to 5 ft.
.MON THROUGH TUE...W wind 15 to 30 kt. Seas 4 to 9 ft.
.WED...S wind up to 15 kt. Seas 5 ft.

$$

PKZ412-170030-
Bering Sea Offshore 171W to 180 and North of 56N-
359 AM AKDT Sat Sep 16 2017

...GALE WARNING TODAY...

.TODAY...NW wind 25 to 40 kt. Seas 12 to 20 ft.
.TONIGHT...NW wind 15 to 30 kt. Seas 8 to 13 ft.
.SUN...NW wind 10 to 20 kt. Seas 6 to 9 ft.
.SUN NIGHT...NW wind 15 kt. Seas 3 to 6 ft.
.MON THROUGH TUE...SW wind 20 to 35 kt. Seas 7 to 12 ft.
.WED...Variable wind 10 kt. Seas 3 to 6 ft.

$$

PKZ413-170030-
Bering Sea Offshore 171W to 180 and South of 56N-
359 AM AKDT Sat Sep 16 2017

...GALE WARNING TODAY...

.TODAY...W wind 20 to 35 kt. Seas 12 to 20 ft.
.TONIGHT...NW wind 10 to 25 kt. Seas 8 to 13 ft.
.SUN...N wind 10 to 15 kt. Seas 6 to 9 ft.
.SUN NIGHT...N wind 15 kt. Seas 5 ft.
.MON THROUGH TUE...W wind 10 to 25 kt. Seas 3 to 7 ft.
.WED...N wind 10 kt. Seas 4 ft.

$$

PKZ414-170030-
Bering Sea Offshore East of 171W-
359 AM AKDT Sat Sep 16 2017

...STORM WARNING TODAY...

.TODAY...NW wind 35 to 50 kt diminishing to 25 to 40 kt in the
afternoon. Seas 14 to 29 ft. Rain showers.
.TONIGHT...NW wind 25 to 40 kt becoming W 20 to 30 kt after
midnight. Seas 12 to 20 ft.
.SUN...NW wind 15 to 30 kt. Seas 8 to 13 ft.
.SUN NIGHT...NW wind 10 to 25 kt. Seas 5 to 9 ft.
.MON...W wind 15 to 30 kt. Seas 3 to 8 ft.
.TUE...SE wind 15 to 30 kt. Seas 3 to 8 ft.
.WED...N wind 10 kt. Seas 4 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
512 AM AKDT Fri Sep 15 2017

.ANALYSIS AND UPPER LEVELS...
Water vapor satellite imagery shows a double-barreled low over
the Bering and Arctic early this morning. The low center over the
Bering is stacked and will be the main weather challenge for the
short term forecast. The ridge which was over the Alcan border
yesterday, shifted further east across British Columbia. At the
surface, a weak trough pulled a front inland across Southcentral
overnight bringing a few showers across the region. A weak
boundary remains along the northeast gulf and Prince William Sound
with showers continuing to develop along the boundary. To the
west, the low over the central Bering waters is rapidly deepening
about 200 miles west of the Pribilof Islands and is approximately
982 mb early this morning. Gusty southeasterly flow along the
eastern waters had reported gusts between 40 to 50 mph with winds
across the western waters gusting up to the same strength out of
the west.

&&

.MODEL DISCUSSION...
Models continue to be in relatively good agreement with the
overall synoptic pattern through Saturday, however they still
have differences with the strength and track of the quickly
developing storm system over the Bering. The ECMWF continues to be
the favored model for the storm track and strength from the 00Z
models. Higher resolution of the NAM was used for the Gulf and
local edit areas of Southcentral.

&&

.AVIATION...
PANC...VFR conditions are expected through the next TAF package.
Light southerly winds are expected to increase this afternoon as
the storm system to the west strengthens. Winds are expected to
taper off late tonight as the pressure re-orients to a down inlet
flow ahead of an approaching front. Kept winds southeasterly
overnight as models have struggled with a new low center expected
to develop early Saturday morning over the western gulf.

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

A weakening front continues to support widespread showers along
the northern Gulf of Alaska Coast this morning and in the western
Cook Inlet and Susitna Valley. A coastal ridge and low level jet
remains intact this morning, which continues to support broad
southeasterly downsloping winds across the west Kenai Peninsula,
Anchorage Bowl and Matanuska Valley. Although moisture is
sufficient, downsloping continues to significantly limit rain in
these areas. There is a little more uncertainty for the Saturday
forecast as a triple point low develops in the Gulf of Alaska. The
latest models are trending in a more well-developed low with a
more potent but brief low level jet along the north Gulf of Alaska
coast. Models are also trending for more widespread moderate to
heavy rains along the coast which could result in a fairly soggy
Saturday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
An approaching Bering Sea front and low pressure system will
return rain and gusty winds to the area this afternoon. The front
quickly washes out late tonight leaving much of the mainland in a
moist cyclonic flow and more showery precipitation rather than
widespread rain. The responsible upper level trough lingers
through the weekend leaving a chance of showers and relatively
light northerly winds.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The focus remains on the developing fall storm west of the
Pribilof Islands. The swath of strongest winds still looks to clip
the Islands, especially Saint George as the system pulls to the
east this evening. The High Wind Watch has been upgraded to a High
Wind Warning. Rain will come with the winds on the backside of
the system overnight. The strongest winds will shift toward the
Alaska Peninsula overnight into Saturday before slowly tapering
down through the weekend.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The long term outlook will feature a somewhat complicated pattern
beginning next week with various model solutions and little
consensus, keeping overall forecast confidence past day 4 low at
this point. To start, a strong low pressure system originating in
the Bering Friday/Saturday will move into the Gulf of Alaska and
then east into Southeast Alaska while weakening by early next
week. On Monday, models are showing a weak shortwave trough
dropping out of the Arctic, riding the back end of the upper level
trough over the state, which will lead to more unsettled weather
for southwest and southcentral Alaska keeping temperatures cool.
By midweek, a low pressure system supported by an active sub-
tropical jet forms south of the western Aleutians then heads east
skirting the island chain. Models diverge greatly at this point
with the GFS taking the system too far south to impact out area,
while the EC takes a more northerly trajectory bringing a front
with heavy rain up through southwest and eventually into
southcentral by Wednesday evening. Since the EC has been more
consistent over the past week with handling a more amplified flow,
the forecast trended towards the later solution.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning...195.
MARINE...Storms..165 170 179
Gales...150 155 160 171 172 173 174 175 176 180 181 185.
FIRE WEATHER...NONE.

&&

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