Gale Warning 22, NWS Anchorage, AK

388 
FZAK62 PAFC 292057 AAA
OFFALU

OFFSHORE WATERS FORECAST...UPDATED
NATIONAL WEATHER SERVICE ANCHORAGE AK
1157 AM AKST SUN JAN 29 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.

PKZ499-300415-
1157 AM AKST SUN JAN 29 2017
.SYNOPSIS FOR CENTRAL BERING SEA...
BOGOSLOF VOLCANO AT 54N 168W REMAINS ACTIVE. A 980 MB LOW AT 54N
172E MOVES TO 61N 179W AT 976 MB TONIGHT AND THEN MOVES INLAND
OVER EASTERN SIBERIA BY MON NIGHT. AN ASSOCIATED FRONT OVER THE
CENTRAL ALEUTIANS MOVES ONSHORE OVER SOUTHWEST ALASKA TONIGHT.
ANOTHER FRONT WILL ENTER THE WESTERN ALEUTIANS MON NIGHT.

$$

PKZ411-300415-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE-
1157 AM AKST SUN JAN 29 2017

.TODAY...SW WIND 10 TO 25 KT. N OF 56N...E WIND 15 TO 25 KT
BECOMING VARIABLE 10 KT IN THE AFTERNOON. SEAS 5 TO 10 FT. 
.TONIGHT...W WIND 15 TO 30 KT. SEAS 8 TO 13 FT. 
.MON...NW WIND 15 TO 30 KT. SEAS 10 TO 14 FT. FREEZING SPRAY. 
.MON NIGHT...SW WIND 15 TO 30 KT. SEAS 8 TO 13 FT. 
.TUE...SE WIND 35 TO 50 KT. SEAS 13 TO 21 FT. 
.WED...SE WIND 35 TO 50 KT. SEAS 23 TO 31 FT. 
.THU...SE WIND 20 TO 30 KT. SEAS 14 TO 20 FT.

$$

PKZ412-300415-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N-
1157 AM AKST SUN JAN 29 2017

...GALE WARNING THROUGH TONIGHT...

.TODAY...SE WIND 25 TO 40 KT. SEAS BUILDING TO 8 TO 18 FT IN THE
AFTERNOON. RAIN SHOWERS.
.TONIGHT...SW WIND 30 TO 45 KT DIMINISHING TO 25 TO 35 KT AFTER
MIDNIGHT. SEAS 13 TO 19 FT. RAIN SHOWERS. 
.MON...SW WIND 15 TO 30 KT BECOMING NW IN THE AFTERNOON.  SEAS
12 TO 16 FT. FREEZING SPRAY IN THE AFTERNOON. 
.MON NIGHT...W WIND 10 TO 20 KT. SEAS 10 TO 15 FT. 
.TUE...S WIND 30 TO 45 KT. SEAS 11 TO 19 FT. 
.WED...SE WIND 35 TO 50 KT. SEAS 14 TO 29 FT. 
.THU...E WIND 30 KT. SEAS 14 TO 21 FT.

$$

PKZ413-300415-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N-
1157 AM AKST SUN JAN 29 2017

...GALE WARNING TODAY...

.TODAY...S WIND 30 TO 45 KT BECOMING SW 20 TO 35 KT IN THE
AFTERNOON. SEAS 8 TO 16 FT. RAIN SHOWERS. 
.TONIGHT...SW WIND 15 TO 30 KT. SEAS 9 TO 14 FT. 
.MON...SW WIND 15 TO 30 KT. SEAS 10 TO 14 FT. 
.MON NIGHT...W WIND 10 TO 25 KT. SEAS 10 TO 13 FT. 
.TUE...SE WIND 35 TO 50 KT. SEAS 13 TO 21 FT. 
.WED...SE WIND 35 TO 50 KT. SEAS 16 TO 29 FT. 
.THU...E WIND 20 TO 30 KT. SEAS 13 TO 19 FT.

$$

PKZ414-300415-
BERING SEA OFFSHORE EAST OF 171W-
1157 AM AKST SUN JAN 29 2017

...STORM WARNING TODAY...

.TODAY...S WIND 20 TO 35 KT BECOMING SE 35 TO 50 KT IN THE
AFTERNOON. SEAS BUILDING TO 12 TO 18 FT IN THE AFTERNOON. RAIN
SHOWERS.
.TONIGHT...S WIND 30 TO 45 KT BECOMING SW 20 TO 35 KT AFTER
MIDNIGHT. SEAS 12 TO 18 FT. 
.MON...SW WIND 10 TO 25 KT. SEAS 9 TO 15 FT. 
.MON NIGHT...SW WIND 10 TO 20 KT. SEAS 8 TO 11 FT. 
.TUE...SW WIND 15 TO 30 KT. SEAS 6 TO 11 FT. 
.WED THROUGH THU...E WIND 20 TO 35 KT. SEAS 9 TO 14 FT.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
403 PM AKST Sat Jan 28 2017

.ANALYSIS AND UPPER LEVELS...
The large low that was in the northern Gulf of Alaska has moved on
shore near Yakutat and continues to move northward. This low is
the source of the snow that has been in Prince William Sound and
from Anchorage northward to the Alaska Range.
Cold air advection up Cook Inlet is expected to keep some snow in
the Mat-SU Valleys and Anchorage Bowl into the evening.
A fairly strong upper level wave is moving across the Eastern
Aleutians and Alaska Peninsula today and bringing convective snow
showers to the region. This wave is tracking northeastward and
toward the Gulf of Alaska.
Farther west there is a low in the western Bering sea moving
eastward which will become a significant weather maker for the
Bering Sea region and Southwest mainland Alaska for the early part
of next week.

&&

.MODEL DISCUSSION...
Models seem to have a handle on the synoptic situation and are
consistent with the overall pattern into the middle of next week.
They are experiencing some differences with a wave moving along
the Eastern Aleutians and Alaska Peninsula and the development of
a low currently west of Attu. The wave moving up the Alaska
Peninsula will move northeast over the next day with the higher
resolution Canadian and NAM models bringing it up Cook Inlet which
will kick off some snow showers around the Cook Inlet region
tomorrow. The GFS and ECMWF both move this wave farther eastward
pushing the heavier snow showers into Prince William Sound. The
other issue is with the low in the far western Bering Sea. The
real challenge with this system is that there will likely be
around three separate centers in the complex system and the ECMWF,
NAM and Canadian are trying to resolve the interactions of these
centers which make the low a bit of an amorphous mess. The GFS
decided to consolidate the energy into a single center which is
probably a good average position of the complex low, but a poor
reflection of the way this low will actually behave.

&&

.AVIATION...
PANC...Snow will continue to taper off early this evening and
that should improve the ceilings and visibilities around PANC. The
one lingering question is whether there will be any fog that
develops after the snow stops. While this remains a possibility,
the southerly winds are expected to keep the atmosphere mixed
enough to keep it from developing.

&&

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

A negative tilt arctic trough will move east tonight. The
associated deformation band which formed as a gulf low merged with
the aforementioned feature will also shift east into the Copper
River Basin. Cold air advection is infiltrating east of the
Alaska Range and will briefly enhance snow from the Anchorage north
to the Matanuska Valley this evening before snow slowly tapers off
and ends overnight. An additional 1-3 inches is possible. Snow
will linger in the Copper Basin through most of the day tomorrow
before ending.

Confidence drops off fast tomorrow afternoon and evening as an
elongated shortwave trough moves into south central Alaska from
the west. Current satellite imagery of the system shows the best
low level convergence and organization south of the Aleutian
Islands, and it is expected that the low will develop somewhere
south of the Alaska Peninsula tonight. As it lifts into south
central Alaska tomorrow the track will most likely remain south
of the Kenai Peninsula, but there is still uncertainty so areas
north of the Kenai may see some afternoon snow, but confidence is
very low. The best shot for snow will be along the Kenai Peninsula
and into Prince William Sound.

Another front will begin to spread more clouds and moisture along
with snow along the Western Alaska Range and rain/snow along the
Kenai Peninsula coast Monday. Strong lee side precipitation shadowing
will keep inland locations dry.

&&

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

Scattered snow showers will continue across southwest Alaska
through much of Sunday as a combination of onshore flow persists
and a series of upper level troughs push through the region. The
bulk of the snow showers will likely fall over coastal locations
with the lower Kuskokwim Valley likely seeing very few showers. By
Sunday night (06Z Monday), a potent frontal boundary will push
inland over western Alaska and bring a nice push of moderate to
heavy snow and strong wind gusts. The biggest question at this
time is how much warm air is advected out ahead of the front. With
the last system that brought blizzard conditions to the Kuskokwim
Delta, the antecedent air mass was much colder which allowed
warmer air to overrun the colder air mass and not modify as
rapidly. However, on Sunday night, the air mass should modify
pretty swiftly in response to the warmer air being advected
northward. In addition, winds will be gusty from the southeast
and not the northeast like the previous event.

Nevertheless, a blizzard watch was issued with the afternoon
package for coastal locations in the Kuskokwim Delta.
Precipitation intensity should be heavy enough to keep the lowest
levels saturated which should aid in keeping temperatures at or
below freezing although guidance wants to warm them above
freezing. With precipitation lagging for inland locations, they
will likely mix with or transition to rain Monday morning as
temperatures warm ahead of the front. While this situation is not
the most ideal for blizzard conditions, wind gusts 50 to 60 mph
with moderate to heavy snow should briefly reduce visibility to
1/2 to 1/4 mile at times Monday morning.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

Scatterometer and satellite imagery depict a surface low developing
over the Pacific Ocean between Shemya and the Kamchatka Peninsula.
This low is forecast to track near Shemya Sunday morning and near
Saint Matthew Island early Monday morning. While this low travels
east, it will push a gale force front across the central and
eastern Aleutians Sunday morning and could strengthen to a storm
force front as a triple point low develops along the front Sunday
afternoon and compacts the pressure gradient further. This low
will shift east into the western Gulf of Alaska Monday afternoon.
Precipitation type remains a bit tricky but with decent warm air
advection associated with the frontal boundary, the strongest
winds will likely coincide with rain and not snow which will
eliminate any possibility of blowing snow or blizzard concerns.

&&

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

A front near the Alaska Peninsula will decay over the Aleutian
Range and south central Alaska Monday night into Tuesday. In the
process it will bring snow to both sides of the Aleutian Range,
the Alaska Range north to Denali, as well as the Kenai and Chugach
Mountains. Out west a fast moving storm force front will move
into the western Bering Sea, with snow changing to rain on Tuesday
over the western Aleutians.

By early Wednesday the Bering front reaches eastern Russia, with
gales and storm force winds slowly diminishing over the region
into the weekend. The front in the east decays into a trough along
the North Gulf Coast, with precipitation diminishing to showers
through the week. High pressure will build across mainland Alaska through
the week. Warm air over the Bering Sea cools by midweek, while
cold air associated with the mainland High becomes more entrenched
over south central Alaska through the week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Blizzard Watch zone 155.
MARINE...Storm 414 170 173 174 176. Gale 351 412 413 119 120 130
141 150 155 160 165 172 175 177 179 180 181 185.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...JA
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MC
LONG TERM...DS