Gale Warning 680, NWS Anchorage, AK

020 
FZAK61 PAFC 281230
OFFAER

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
330 AM AKST MON NOV 28 2016

OFFSHORE WATERS FORECAST FOR THE GULF OF ALASKA WEST OF 144W

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.

PKZ399-290145-
330 AM AKST MON NOV 28 2016
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A NORTH PACIFIC 995 MB LOW MOVES TO 54N 148W THIS EVENING AT 977
MB...THEN MOVES TO 59N 140W TUE EVENING AND MAINTAINS STRENGTH. THE
ASSOCIATED FRONT PUSHES OVER THE GULF OF ALASKA THROUGH TUE AFTERNOON.
A NEW FRONT ENTERS THE SOUTHWESTERN GULF LATE TUE NIGHT.


$$

PKZ351-290145-
GULF OF ALASKA OFFSHORE NORTH OF 57N AND WEST OF 144W-
330 AM AKST MON NOV 28 2016

...STORM WARNING TONIGHT AND TUESDAY...

.TODAY...W WIND 15 TO 30 KT BECOMING SW UP TO 15 KT IN THE
AFTERNOON. SEAS 10 TO 18 FT SUBSIDING TO 7 TO 12 FT IN THE
AFTERNOON.
.TONIGHT...E WIND 15 TO 30 KT BECOMING NE 35 TO 50 KT AFTER
MIDNIGHT. SEAS 5 TO 9 FT BUILDING TO 12 TO 19 FT AFTER MIDNIGHT.
RAIN.
.TUE...N WIND 35 TO 50 KT. SEAS 14 TO 21 FT. RAIN SHOWERS.
.TUE NIGHT...W WIND 35 TO 50 KT. SEAS 13 TO 21 FT.
.WED THROUGH THU...SW WIND 15 TO 30 KT. SEAS 9 TO 16 FT.
.FRI...W WIND 25 TO 40 KT. SEAS 13 TO 21 FT.

$$

PKZ352-290145-
GULF OF ALASKA OFFSHORE SOUTH OF 57N NORTH OF 55N AND WEST OF
144W-
330 AM AKST MON NOV 28 2016

...STORM WARNING TONIGHT AND TUESDAY...

.TODAY...SW WIND UP TO 20 KT BECOMING SE 10 TO 25 KT IN THE
AFTERNOON. SEAS 9 TO 17 FT. WIDESPREAD RAIN SHOWERS.
.TONIGHT...E WIND 35 TO 50 KT. SEAS 12 TO 18 FT. RAIN SHOWERS.
.TUE...NW WIND 35 TO 50 KT. SEAS 16 TO 26 FT. RAIN SHOWERS.
.TUE NIGHT...W WIND 35 TO 50 KT. SEAS 15 TO 23 FT.
.WED THROUGH THU...SW WIND 15 TO 30 KT. SEAS 11 TO 19 FT.
.FRI...W WIND 25 TO 40 KT. SEAS 16 TO 24 FT.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
353 AM AKST Sun Nov 27 2016

.ANALYSIS AND UPPER LEVELS...

The main feature impacting southern Alaska and surrounding marine
areas is the stacked low moving east across the Gulf of Alaska
this morning. The low has thus far traversed far enough south and
is strong enough that low-level offshore flow has dried out the
lower levels, and that has limited snow to mainly coastal
locations for much of the overnight period across the Southcentral
region. ASCAT winds from late last evening depicted storm-force
winds continuing to the south of the low over the southern Gulf of
Alaska.

Over Southwest Alaska, a shortwave trough approaching from the
southwest combined with a leftover low-level baroclinic boundary
are helping to keep light snow falling across the Bristol Bay
region. This shortwave trough is situated largely west-east
between the Gulf of Alaska low and another upper low currently
entering the Southwest Bering. Out ahead of this upper-level low,
a strengthening surface and mid-level cyclone continues to cross
the Central Aleutians into the southern Bering. This low will
continue to move east toward the Pribilofs tonight and then the
Alaska Peninsula Monday before dissipating into a trough Monday.

Another seasonably strong low pressure system moves into the
Aleutians and possibly the Bering late Monday night into the
middle of the week. There are model disagreements with this
feature further out in time that will be fine-tuned as the event
approaches.

&&

.MODEL DISCUSSION...

As mentioned in the previous section, with the low remaining
relatively strong enough to induce low-level offshore flow, snow
is having a hard time reaching the ground for inland areas, and
this is helping to increase confidence in continuing to lower
precipitation/snowfall amounts over inland areas of Southcentral.

A main area where there is some model disagreement is with a
strong cyclone poised to move north from the Pacific through the
Gulf and quickly inland over the Alcan border region Monday night
through Tuesday night. The EC is now consistently to the west of
the model suite, moving inland near Cape Suckling, while the GFS
develops more of a double-barreled low that extends well east
through the southeastern Gulf. The NAM may be closest to previous
model runs with a more coherent single circulation making landfall
near Yakutat. For now, given model uncertainty, we are leaving the
forecast largely as-is similar to the NAM model until model
agreement confidence improves.

Another seasonably strong low pressure system moves into the
Aleutians and possibly the Bering late Monday night into the
middle of the week. There are model disagreements with this
feature further out in time that will be fine-tuned as the event
approaches.

&&

.AVIATION...

PANC...Light snow is likely at some point later this morning
through mid-afternoon. The problem is trying to nail down exactly
when and how long that might occur. My hunch is that there will be
a very light snow around the area this morning into early
afternoon, ending as a quick-moving, narrow frontal band that
will drop ceilings to MVFR briefly from the north between 20z and
about 00z. Otherwise, expect VFR conditions with a light
northerly wind as cold air moves into behind the front by the
evening.

&&

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

A weakening 960s mb low over the Gulf combined with cold advection
from the west will increase outflow conditions across the western
Gulf and eastern Kenai Peninsula through tonight. Winds will be
especially gusty near Seward and Whittier, with storms across the
Barren island marine areas. Winds should diminish on Monday. Cold
advection snow showers are expected from Cook inlet to the MAT-SU
Valleys today then diminishing overnight as the offshore flow
increases. The best potential for measurable snowfall in these
areas will be along/near the mountains with upslope enhancement.
The Copper River Basin will likely see measurable snowfall with
the upper trough today and tonight.

The next low pressure system will begin spinning up in the North
Pacific Monday and then rapidly deepen as it tracks into the
southern Gulf Monday night and central Gulf of Alaska Tuesday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Snow showers will linger through the morning along the Aleutian
Range from the last remnants of the low tracking through the Gulf.
Throughout the remainder of the day weak high pressure will build
in before a weak front pushes in Monday morning. The front will
bring light snow to the Bristol Bay area through Monday before
diminishing overnight. Then another weak ridge will build in over
the area from the west.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A quick moving low tracking northward across the Central Aleutians
into the southern Bering is bringing just enough warm air to
bring a mix of rain and snow to the islands. The low will then
track east and bring a rain and snow mix to the Eastern Aleutians,
Pribilof Islands, and Alaska Peninsula into Monday before
diminishing. Monday night a new system over the North Pacific will
bring a front to the Western Aleutians that looks to be warm
enough for rain.

&&

.LONG TERM FORECAST (Days 3 through 7)...

The long term forecast will see a continuation of the active
weather pattern that Alaska has seen over the past one to two
weeks. Another powerful low pressure system will cross from the
North Pacific into the Bering Sea near Adak Tuesday night, which
will bring yet another borderline gale-force to storm-force low
into the Bering Sea. At the same time, a deepening area of low
pressure in the northern Gulf of Alaska will be sprinting
northward before making landfall along the Gulf coast near
Yakutat. Both of these systems are expected to bring plenty of
rainfall/snowfall to much of the area. However, much of Southwest
and Southcentral Alaska will remain on the dry side until
Wednesday night when the frontal boundary associated with the area
of low pressure in the Bering Sea begins pushing inland.

By Thursday afternoon, the area of low pressure in the Bering Sea
will begin moving inland over Southwest Alaska which will likely
bring a showery regime and a bit of warmer air briefly back to the
state. As the low slides eastward Friday and through the weekend,
cold air on the back side of the low will once again filter in
from the Arctic which will allow below normal temperatures to
build back across Southwest and Southcentral Alaska through the
weekend. While it is hard to nail 6 to 8 days out, it appears
that a decent shot of snow will be possible for inland locations
including Anchorage next weekend as the upper level low moves over
Anchorage and downsloping from the frontal boundary gets negated.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gales...119 120 137 139 150 155 160 170 172-178
         Storms...130-132
         Heavy Freezing Spray...180 181.

&&

SYNOPSIS AND MODEL DISCUSSION...CC
AVIATION...CC
SOUTHCENTRAL ALASKA...BC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...MC