Gale Warning 23, NWS Anchorage, AK

854 
FZAK62 PAFC 301250
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
350 AM AKST MON JAN 30 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.

PKZ499-310215-
350 AM AKST MON JAN 30 2017
.SYNOPSIS FOR CENTRAL BERING SEA...
BOGOSLOF VOLCANO AT 54N 168W REMAINS ACTIVE. A 978 MB LOW AT 61N
175W EXITS NORTH TO THE CHUKCHI SEA TONIGHT. A 985 MB LOW AT 55N
178E WEAKENS TO A TROUGH OF LOW PRESSURE OVER THE CENTRAL BERING
TODAY. A FRONT ALONG THE EASTERN BERING AND SOUTHWEST ALASKA COAST
PUSHES INLAND TODAY. ANOTHER FRONT ENTERS THE SOUTHWEST BERING
TONIGHT AND MOVES TO THE CENTRAL BERING TUE NIGHT.

$$

PKZ411-310215-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE-
350 AM AKST MON JAN 30 2017

...STORM WARNING TUESDAY...

.TODAY...W WIND 15 TO 30 KT. SEAS 9 TO 12 FT. FREEZING SPRAY.
.TONIGHT...SE WIND 10 TO 25 KT INCREASING TO 25 TO 35 KT AFTER
MIDNIGHT. SEAS 8 TO 11 FT. FREEZING SPRAY IN THE EVENING.
.TUE...SE WIND 35 TO 50 KT. SEAS 9 TO 15 FT BUILDING TO 15 TO
23 FT IN THE AFTERNOON. RAIN AND SNOW.
.TUE NIGHT...SE WIND 50 KT. SEAS 18 TO 29 FT.
.WED...SE WIND 40 TO 55 KT. SEAS 18 TO 33 FT.
.THU THROUGH FRI...E WIND 15 TO 30 KT. SEAS 14 TO 21 FT.

$$

PKZ412-310215-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N-
350 AM AKST MON JAN 30 2017

...GALE WARNING TUESDAY...

.TODAY...SW WIND 10 TO 25 KT. SEAS 9 TO 12 FT.
.TONIGHT...W WIND 10 TO 25 KT. SEAS 9 TO 12 FT.
.TUE...SE WIND 10 TO 25 KT INCREASING TO 20 TO 35 KT IN THE
AFTERNOON. SEAS 8 TO 11 FT BUILDING TO 9 TO 14 FT IN THE
AFTERNOON.
.TUE NIGHT...SE WIND 30 TO 45 KT. SEAS 11 TO 19 FT.
.WED...SE WIND 35 TO 50 KT. SEAS 14 TO 29 FT.
.THU...SE WIND 25 TO 35 KT. SEAS 14 TO 22 FT.
.FRI...E WIND 30 KT. SEAS 9 TO 14 FT.

$$

PKZ413-310215-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N-
350 AM AKST MON JAN 30 2017

...GALE WARNING TUESDAY...

.TODAY...SW WIND 20 TO 30 KT. SEAS 9 TO 13 FT.
.TONIGHT...SW WIND 15 TO 30 KT. SEAS 9 TO 13 FT.
.TUE...S WIND 20 TO 35 KT BECOMING SE 30 TO 45 KT IN THE
AFTERNOON. SEAS 9 TO 12 FT BUILDING TO 10 TO 18 FT IN THE
AFTERNOON.
.TUE NIGHT...SE WIND 35 TO 50 KT. SEAS 13 TO 21 FT.
.WED...SE WIND 40 TO 55 KT. SEAS 15 TO 29 FT.
.THU THROUGH FRI...E WIND 20 TO 35 KT. SEAS 11 TO 19 FT.

$$

PKZ414-310215-
BERING SEA OFFSHORE EAST OF 171W-
350 AM AKST MON JAN 30 2017

.TODAY...SW WIND 15 TO 30 KT. SEAS 9 TO 14 FT.
.TONIGHT...SW WIND 10 TO 25 KT. SEAS 7 TO 11 FT.
.TUE...W WIND 10 TO 20 KT BECOMING S IN THE AFTERNOON.
SEAS 7 TO 11 FT.
.TUE NIGHT...SE WIND 15 TO 30 KT. SEAS 6 TO 9 FT.
.WED THROUGH FRI...E WIND 20 TO 35 KT. SEAS 7 TO 12 FT.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
519 AM AKST Sun Jan 29 2017

.ANALYSIS AND UPPER LEVELS...
Several troughs rotating around an upper level low centered near
the Bering Strait are impacting the area this morning. One trough,
located near Prince William Sound, is swinging inland across the
northern Gulf Coast, while a second is tracking along the Alaska
Peninsula and into the western Gulf. Thunderstorms embedded in the
leading edge of the area of enhanced snow showers associated with
the second trough have been bringing lightning to Kodiak Island,
Shelikof Strait and the western Gulf this morning. In between the
two troughs, a small transient ridge is building into Southcentral
Alaska.

Out west, a vertically stacked low is located north of Shemya with
an associated front stretching across the western and central
Bering. A developing frontal wave is in the process of crossing
the Aleutian chain just to the west of Adak, with an associated
strong frontal system pushing east through central Aleutians.

&&

.MODEL DISCUSSION...
Models remain in good synoptic agreement. Some small differences
exist in the handling of the upper level trough swinging through
the western Gulf today. While all the models take the small
associated surface low on a similar track up Shelikof Strait and
then along southeastern Kenai coast, the Canadian takes a small
secondary trough up the western Kenai Peninsula brushing through
the Anchorage area and Matanuska Valley. The consequences of this
solution being correct would be some additional scattered snow
showers further inland, however given that it is the only model
suggesting this it was deemed an outlier.

Forecast challenges for the western domain include the timing of
the front coming in from the west as well as how fast the south to
southeasterly flow ahead of it warms temperatures...thus impacting
the likelihood and magnitude of snow and blowing snow concerns for
southwest Alaska.

&&

.AVIATION...
PANC...Some patchy fog is possible through early afternoon as mid
and high level clouds break up in response to a small ridge
building over the area but otherwise expect VFR conditions to
persist through Monday morning.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
A neutrally tilted trough along the Alaska Peninsula this morning
will march eastward across the Gulf today through tonight, taking
on a slight negative tilt as it enters the western Gulf this morning.
Instability is quite impressive out ahead of it, as indicated by
cold cloud tops in infrared satellite imagery and recent lightning
strikes near Kodiak Island. 12Z sounding from Kodiak also shows
lapse rates around 9 degrees C/km for much of the column. Thus,
expect moderate to heavy showers right out ahead of the strongest
part of the upper short-wave.

It is quite difficult to pinpoint the track of these showers as
indicated by the differences in model guidance. Based on latest
trends in satellite and in guidance, there is increasing
confidence that some of the heaviest and more widespread showers
will track along Shelikof Strait this morning up to the southern
Kenai Peninsula this afternoon and then over to Cordova this
evening. Snow accumulation will vary significantly across small
distances, depending on where showers track, but on average expect
around 2 inches snow accumulation with locally higher amounts.
Visibility may drop to half mile or less in heavier showers.

An upper level ridge will build in behind the trough, but dry
weather will be short-lived as a front approaches from the Bering
Sea Monday through Monday Night. This will be a good set-up for
strong low level southeasterly downsloping winds along the Kenai
and Chugach ranges. This will keep areas in the lee mostly dry
while coastal areas and the western Susitna Valley will likely
see quite a bit of precip with deep southerly flow from the sub-
tropics. Cold air feeding into the back side of this system means
there will not be a significant warm-up. Thus, precip will fall
mainly as snow, with rain likely relegated to Kodiak Island and
portions of the Gulf coast.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The Southwest Alaska region has a weak shortwave moving through
this morning which is producing some light snow showers in the
Kuskokwim Delta and the Bristol Bay region. Meanwhile, the next
major synoptic feature is a weather front approaching the
Southwest Alaska coastline by Sunday evening. This will result in
blowing snow issues accompanied by moderate to heavy snowfall as
the frontal boundary moves inland before exiting the region by
Monday morning. The strongest southeasterly winds and snowfall
will occur along the Kuskokwim Delta coastline and along the
Western Capes northward extending through the Ahklun Mountains.
Since we have cold air in place over the Kuskokwim Delta region,
this should keep the warm air advection at bay just long enough
for the occurrence of the blowing snow phenomena. Therefore, a
Winter Weather Advisory for Blowing Snow was issued this morning
for the Kuskokwim Delta region west of Bethel.

The warmer air upstream will modify the air mass resulting in
temperatures reaching in the upper 30s for the Kuskokwim Delta
interior. As the aforementioned front moves through the Bristol
Bay region the temperatures are warmer along the coast, but cooler
air is in the interior. Therefore, a Winter Weather Advisory for
Snow was issued north and west of Dillingham after midnight
tonight through Monday afternoon as the frontal boundary moves
through the region.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The storm force low is tracking into the southern Bering Sea this
morning. The satellite imagery is showing a huge comma cloud over
the Central Aleutians with moisture streaming northward into the
Bering Sea. This will bring a strong push of warmer temperatures
to the Central/Eastern Aleutians northward into the Bering as the
low tracks into the northern Bering by Sunday evening. This will
bring gale to storm force southerly winds along the Central/Eastern
Aleutians with strong gusty gap winds out of the bays and passes
through Monday as the front moves eastward. By Monday the majority
of the Bering/Aleutians will have westerly flow accompanied by a
showery weather regime. By late Monday evening the next storm
force low tracks south of the Western Aleutians with the
associated weather front approaching the aforementioned region.
This results in a significant warm-up along the Western Aleutians
spreading northward into the Bering Sea.

&&

.LONG TERM FORECAST (Days 3 through 7)...
A front near the AKpen will decay over the Aleutian Range and
southcentral AK Mon night into Tue. 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,
with snow changing to rain on Tue over the western Aleutians.

By early Wed 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 AK
through the week. Warm air over the Bering cools by midweek,
while cold air associated with the mainland high becomes more
entrenched over Southcentral through the week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Heavy Freezing Spray Warning 185.
 		 Storm Warning 170 172 173 174 176.
 		 Gale Warning 132 150 155 160 165 171 175 179 180 181 185.

&&

SYNOPSIS AND MODEL DISCUSSION...JR
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
LONG TERM...DS