Storm Warning 82, NWS Anchorage, AK

446 
FZAK62 PAFC 131706 AAA
OFFALU

Offshore Waters Forecast...UPDATED
National Weather Service Anchorage AK
906 AM AKDT Tue Sep 13 2022

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.

PKZ499-140015-
906 AM AKDT Tue Sep 13 2022
.SYNOPSIS FOR CENTRAL BERING SEA...
This afternoon a 1001 mb low will move to 56N 167E. This low will 
deepen to 973 mb and move to 61N 175W Thursday morning. A 960 mb low 
will move to 48N 172E Thursday afternoon.

$$

PKZ411-140015-
Bering Sea Offshore West of 180 and East of the International
Dateline-
906 AM AKDT Tue Sep 13 2022

...GALE WARNING TONIGHT AND WEDNESDAY...

.TODAY...SW wind 10 to 20 kt. Seas 4 to 7 ft.
.TONIGHT...SW wind 10 to 25 kt becoming S 20 to 35 kt after
midnight. Seas 5 to 10 ft. Rain.
.WED...W wind 30 to 45 kt. Seas 10 to 18 ft.
.WED NIGHT...W wind 25 to 40 kt. Seas 8 to 16 ft.
.THU...NE wind 40 to 55 kt. Seas 14 to 22 ft.
.FRI...SW wind 45 to 60 kt. Seas 24 to 38 ft.
.SAT...SW wind 15 to 25 kt. Seas 9 to 15 ft.

$$

PKZ412-140015-
Bering Sea Offshore 171W to 180 and North of 56N-
906 AM AKDT Tue Sep 13 2022

...GALE WARNING WEDNESDAY...

.TODAY...W wind 20 kt. Seas 6 ft.
.TONIGHT...SW wind 10 to 25 kt. Seas 6 ft.
.WED...S wind 20 to 35 kt becoming SW 30 to 45 kt in the
afternoon.
Seas 8 to 13 ft building to 11 to 19 ft in the afternoon.
.WED NIGHT...SW wind 35 to 50 kt. Seas 13 to 21 ft.
.THU...SW wind 25 to 40 kt. Seas 9 to 14 ft.
.FRI...SW wind 40 to 55 kt. Seas 25 to 42 ft.
.SAT...SW wind 15 to 25 kt. Seas 12 to 20 ft.

$$

PKZ413-140015-
Bering Sea Offshore 171W to 180 and South of 56N-
906 AM AKDT Tue Sep 13 2022

.TODAY...W wind 15 to 25 kt. Seas 6 ft.
.TONIGHT...SW wind 15 to 25 kt. Seas 7 ft.
.WED...SW wind 15 to 30 kt. Seas 8 to 12 ft.
.WED NIGHT...W wind 10 to 25 kt. Seas 7 to 12 ft.
.THU...S wind 40 to 55 kt. Seas 13 to 21 ft.
.FRI...SW wind 50 to 65 kt. Seas 32 to 48 ft.
.SAT...SW wind 20 kt. Seas 10 to 16 ft.

$$

PKZ414-140015-
Bering Sea Offshore East of 171W-
906 AM AKDT Tue Sep 13 2022

.TODAY...W wind 20 to 30 kt. Seas 7 to 11 ft.
.TONIGHT...W wind 10 to 25 kt. Seas 7 ft.
.WED...SW wind 10 to 20 kt becoming S 15 to 30 kt in the
afternoon. Seas 5 to 9 ft. Rain.
.WED NIGHT...SW wind 25 kt. Seas 7 to 12 ft.
.THU...SW wind 25 to 40 kt. Seas 9 to 14 ft.
.FRI...SW wind 30 to 45 kt. Seas 18 to 32 ft.
.SAT...SW wind 15 to 25 kt. Seas 13 to 21 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
458 PM AKDT Mon Sep 12 2022

.ANALYSIS AND UPPER LEVELS...

A vertically stacked low is near Nunivak Island this afternoon.
The occluded front is wrapped around it a number of times with
multiple waves progressing from south-to-north over Southcentral
and Southwest Alaska. Showers are occurring with each of these
waves over all of southern Alaska with the heaviest rainfall
along the north Gulf coast. There are not any long taps of
moisture feeding into this system so that has helped to limit
precipitation amounts with the heavier showers being mostly due
to colder air aloft enhancing the convection.

Though it is still far away, tropical Storm 'Merbok' can be seen
on satellite near 25N 165E. This storm will move northward and
become a significant low in the Bering Sea region from late
Wednesday through the remainder of the week.

&&

.MODEL DISCUSSION...

Models are in good agreement through the next few days. There is a
little bit of model spread in the timing of the low moving across
the northern Bering Sea Tuesday night through Thursday, but this
will mainly affect wind direction and rainfall timing for the
northern Bering Sea and northern half of the Kuskokwim Delta.

After that, the attention turns to the large low that will move
through the Bering and into Southwest Alaska during the second
half of this week. This low is the remnants of tropical storm
"Merbok", and tropical systems have a propensity to cause
problems for the numerical weather models. At this time, the good
news is that the GFS and ECMWF are very well aligned in track,
timing, and strength as this low moves across the Bering Sea. The
Canadian GEM model is notably weaker and farther east than that of
the GFS/EC solutions. Especially with the 12Z EC shifting to
nearly match the GFS, it looks like this is the more favorable
track at this time.

&&

.AVIATION...

PANC...Southeast surface winds this afternoon and evening should
diminish around midnight. However, there could be some low level
wind shear as a result as winds aloft will likely remain from the
southeast even as surface winds become light. Expect more
rainfall as well but mainly VRF conditions should remain. There is
a chance of an occasional MVFR ceiling though Tuesday afternoon.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
3: Tonight through Thu afternoon)...

A large longwave trough remains in place across much of Alaska. An
upper level low currently spinning over Nunivak Island will only
continue to slowly move eastward over the next few days. As a
result, multiple upper level shortwaves in the flow around the
this upper level low will continue to bring periods of rain to
much of Southcentral tonight through Tuesday. There still remains
some uncertainty as to whether or not a secondary low will
develop southwest of Middleton Island which, if it happens, would
bring even heavier rainfall to Prince William Sound along with a
steadier rain for the Cook Inlet region including Anchorage. The
timing on this would be Tuesday morning through Tuesday night.
Also, small craft advisory winds are expected along the north Gulf
Coast overnight into Tuesday morning due to a tightening gradient
and a potential surface low developing.

Tuesday night into Wednesday, the center axis of the upper level
trough moves overhead with the center of the upper level low
moving eastward across the Kenai Peninsula. As this moves through,
expect any organized rainfall to become more showery in nature as
it moves through.

Late Wednesday through Thursday, the whole upper level trough
continues moving off to the east with some upper level ridging
building in behind it. Therefore, expect improving conditions late
in the day on Wednesday with perhaps even, yes, SUNSHINE. Partly
cloudy conditions are expected with the potential for patchy fog
in some areas though any fog at this point is low confidence and
held off on placing it into this forecast package. Thursday looks
to start off fairly nice with some sunshine before the next
frontal system begins to encroach on the area. However, the timing
and evolution of the pattern becomes low confidence at this
point. Stay tuned for subsequent forecast updates.

&&

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

A weakening low currently positioned near Nunivak Island is
slowly moving east along the Kuskokwim Delta coast. As the low
moves further inland, widespread rain showers with gusty
northwesterly winds over the Alaska Peninsula will persist for
most of Tuesday. By early Wednesday, we will see a brief break of
drier weather as a transient ridge of high pressure builds
overhead.

Thereafter, all attention turns to the next weather maker as an
upper trough and surface low pressure sets up over the northern
Bering Sea, advancing a front eastward toward western Alaska.
Along and ahead of the front, steadier widespread rain with
southerly winds arrives Wednesday afternoon. Daytime highs will
mostly be in the mid 50s and overnight lows in the low 40s under
cloudy skies. Unsettled conditions continues into Thursday as weak
pieces of energy ahead of the southerly flow ejects into the
forecast area.

&&

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

A weakening low pressure system near Nunivak Island is slowly
moving east along the Kuskokwim Delta coast. Areas of small craft
winds wrapping around the backside of the low over the eastern
Bering Sea continues to track eastward with the low. The winds are
expected to subside by Tuesday night along with rain tapering off
as a transient ridge of high pressure builds overhead. Meanwhile,
an upper trough and surface low pressure sets up over the
northern Bering Sea, advancing a front eastward toward western
Alaska. Between Tuesday night and Wednesday, rain with small craft
winds will occur along the leading edge of the front as it
crosses the western Bering Sea and Aleutians Islands. As the front
pushes east Wednesday evening, gale force winds wraps around the
backside of the low as it approaches Saint Matthew Island.

Attention then turns to remnants of Tropical System 15W
("Merbok") are expected to move from the West Pacific Ocean into
the Bering Sea through the end of the week. The western Aleutians
could potentially experience storm to hurricane force winds and
heavy rain beginning on Thursday as a rapidly deepening low
advances northward. Forecast confidence is low to moderate at the
moment, so stay tuned for the latest forecast updates.

&&
.MARINE (Days 3 through 5: Thursday through Saturday)...

Bering/Aleutians...Gales are likely around a low that moves
through the Northern Bering Sea on Thursday, with seas up to 20
ft. Thursday afternoon through Saturday, a strong North Pacific
low moves across the Aleutian Islands and Bering Sea. Broad areas
of gales are very likely across most of the Bering Sea and
Aleutian Islands, and the potential remains for sustained storm
force winds and hurricane force gusts. Seas around 20 to 30 ft.

Gulf of Alaska...Confidence is moderate that winds will be less
than 35 kt and seas less than 20 ft. There may be localized areas
of gales in the Northern Gulf on Saturday, depending on whether a
developing low is strong enough to produce a barrier jet and
enhance winds out of Kamishak Gap.

&&

.LONG TERM FORECAST (Days 4 through 7: Friday through Monday)...

Expect generally unsettled weather through the extended period,
with brief breaks possible as transient ridges move across
Southcentral Alaska early Friday and across the Bering Sea and
Aleutian Islands on Monday.

The biggest story continues to be the interaction of a Northern
Bering low with the remnants of what is currently Tropical Storm
15W or "Merbok." Models have come into better agreement since
yesterday, increasing our confidence in the strength and track of
these storms. The consensus is that the Northern Bering low will
weaken by Friday, then become subsumed into the remnants of Merbok
in the Southern Bering Sea. The resulting low looks to bring
strong winds and heavy rain over much of the Central and Eastern
Bering Sea as well as the Pribilof Islands and the Central and
Eastern Aleutians. As the low approaches Southwest Alaska Friday
morning, high surf and coastal flooding become concerns. The
influx of southerly to southwesterly gales into Southwest Alaska
is a favorable pattern for coastal flooding, though the speed of
this low and the relatively short duration of strong winds could
reduce concerns. Details remain uncertain for now, especially
given model differences in the track of the low. For Southcentral
Alaska, the fronts from each of these two systems will contribute
to cloudy and rainy conditions. With the low tracking northward
along the Southwest coast, a tightening pressure gradient could
also lead to enhanced easterly winds through Turnagain Arm and
other gaps.

Winds should gradually subside through Saturday as the low
continues north and moves out of the region. Rain showers will
likely continue through Saturday as a longwave trough and several
shortwaves move over the region. By Monday, the weather looks to
become more active as two separate systems enter the region. For
the Southern Mainland, a surface low looks to develop off the base
of the upper level longwave trough and move into the Gulf of
Alaska. Further west, a low in Russia looks to push its gale-force
front into the Western Bering and Aleutians.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...MV
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MF
MARINE/LONG TERM...CL/KC