Gale Warning 681, NWS Anchorage, AK

951 
FZAK62 PAFC 160038
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
338 PM AKST Fri Dec 15 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.

PKZ499-161430-
338 PM AKST Fri Dec 15 2017
.SYNOPSIS FOR CENTRAL BERING SEA...
A 964 mb low at 59N 165W loops over the Eastern Bering then dives
into the Western Gulf of Alaska at 998 mb by Sun afternoon. A 970
mb low near 54N 176W moves to the Northern Gulf of Alaska for Sun
afternoon. The associated front arches over the Bering through 
Sun afternoon.

$$

PKZ411-161430-
Bering Sea Offshore West of 180 and East of the International
Dateline-
338 PM AKST Fri Dec 15 2017

...GALE WARNING TONIGHT AND SATURDAY NIGHT...

.TONIGHT...NW wind 25 to 40 kt. Seas 12 to 20 ft.
.SAT...W wind 10 to 25 kt. Seas 8 to 13 ft.
.SAT NIGHT...SW wind 10 to 25 kt becoming S 25 to 40 kt after
midnight. Seas 8 to 13 ft. Snow.
.SUN...S wind 35 to 50 kt. Seas 14 to 22 ft.
.SUN NIGHT...S wind 30 to 45 kt. Seas 24 to 29 ft.
.MON...SW wind 35 to 50 kt. Seas 25 to 30 ft.
.TUE...SW wind 25 to 35 kt. Seas 16 to 23 ft.
.WED...W wind up to 20 kt. Seas 9 to 14 ft.

$$

PKZ412-161430-
Bering Sea Offshore 171W to 180 and North of 56N-
338 PM AKST Fri Dec 15 2017

...GALE WARNING THROUGH SATURDAY NIGHT...

.TONIGHT...N wind 15 to 30 kt increasing to 25 to 35 kt after
midnight. Seas 9 to 15 ft.
.SAT...NW wind 30 to 40 kt. Seas 12 to 18 ft.
.SAT NIGHT...NW wind 20 to 35 kt. Seas 10 to 18 ft.
.SUN...S wind 25 to 40 kt. Seas 10 to 18 ft.
.SUN NIGHT...S wind 35 to 50 kt. Seas 13 to 28 ft.
.MON THROUGH TUE...SW wind 25 to 40 kt. Seas 18 to 28 ft.
.WED...S wind 15 to 25 kt. Seas 11 to 17 ft.

$$

PKZ413-161430-
Bering Sea Offshore 171W to 180 and South of 56N-
338 PM AKST Fri Dec 15 2017

...GALE WARNING SATURDAY AND SATURDAY NIGHT...

.TONIGHT...NW wind 15 to 30 kt. Seas 9 to 15 ft.
.SAT...NW wind 25 to 40 kt. Seas 12 to 18 ft.
.SAT NIGHT...W wind 20 to 35 kt. Seas 11 to 18 ft.
.SUN...S wind 30 to 45 kt. Seas 13 to 21 ft.
.SUN NIGHT...S wind 35 to 50 kt. Seas 15 to 30 ft.
.MON THROUGH TUE...SW wind 25 to 40 kt. Seas 16 to 27 ft.
.WED...S wind 15 to 25 kt. Seas 10 to 15 ft.

$$

PKZ414-161430-
Bering Sea Offshore East of 171W-
338 PM AKST Fri Dec 15 2017

...GALE WARNING SATURDAY AND SATURDAY NIGHT...

.TONIGHT...W wind 15 to 30 kt. Seas 7 to 12 ft. Snow showers.
.SAT...W wind 25 to 40 kt. Seas 10 to 18 ft. Rain showers.
.SAT NIGHT...NW wind 25 to 40 kt. Seas 13 to 21 ft.
.SUN...W wind 15 to 30 kt. Seas 10 to 18 ft.
.SUN NIGHT...S wind 30 to 45 kt. Seas 10 to 18 ft.
.MON...S wind 30 to 45 kt. Seas 14 to 22 ft.
.TUE THROUGH WED...S wind 15 to 30 kt. Seas 10 to 18 ft.

$$

836 
FZAK62 PAFC 161217
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
317 AM AKST Sat Dec 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.

PKZ499-170215-
317 AM AKST Sat Dec 16 2017
.SYNOPSIS FOR CENTRAL BERING SEA...

A 968 mb low at 61N 167W moves to 57N 160W at 990 mb Sun morning
and then moves into the Gulf and dissipates by Sun night. A front
associated with a 952 mb low at 56N 170E Sun afternoon moves
across the Bering through Mon afternoon. 

$$

PKZ411-170215-
Bering Sea Offshore West of 180 and East of the International
Dateline-
317 AM AKST Sat Dec 16 2017

...STORM WARNING SUNDAY...

.TODAY...NW wind 15 to 30 kt becoming W late afternoon. Seas 9 to 14 ft.
.TONIGHT...SW wind 15 to 30 kt becoming S 25 to 40 kt after midnight.
Seas 9 to 14 ft. Snow.
.SUN...S wind 30 to 45 kt increasing to 40 to 55 kt in the afternoon.
Seas 12 to 20 ft building to 18 to 30 ft in the afternoon. Rain and 
snow.
.SUN NIGHT...SW wind 35 to 50 kt. Seas 25 to 31 ft.
.MON...SW wind 35 to 45 kt. Seas 24 to 29 ft.
.TUE...SW wind 25 to 40 kt. Seas 14 to 27 ft.
.WED...W wind up to 20 kt. Seas 7 to 12 ft.

$$

PKZ412-170215-
Bering Sea Offshore 171W to 180 and North of 56N-
317 AM AKST Sat Dec 16 2017

...GALE WARNING THROUGH SUNDAY...

.TODAY...NW wind 30 to 40 kt. Seas 12 to 18 ft.
.TONIGHT...W wind 25 to 40 kt. Seas 9 to 17 ft.
.SUN...SW wind 15 to 30 kt becoming S 30 to 45 kt in the
afternoon. Seas 8 to 12 ft building to 10 to 18 ft in the afternoon.
Snow and rain.
.SUN NIGHT...S wind 35 to 50 kt. Seas 13 to 28 ft.
.MON THROUGH TUE...SW wind 30 to 45 kt. Seas 17 to 28 ft.
.WED...S wind up to 20 kt. Seas 8 to 13 ft.

$$

PKZ413-170215-
Bering Sea Offshore 171W to 180 and South of 56N-
317 AM AKST Sat Dec 16 2017

...STORM WARNING SUNDAY...

.TODAY...NW wind 25 to 40 kt. Seas 12 to 18 ft.
.TONIGHT...W wind 20 to 35 kt. Seas 11 to 18 ft.
.SUN...SW wind 25 to 40 kt becoming S 35 to 50 kt in the
afternoon. Seas 12 to 20 ft. Rain.
.SUN NIGHT...S wind 40 to 55 kt. Seas 15 to 30 ft.
.MON THROUGH TUE...SW wind 30 to 45 kt. Seas 16 to 27 ft.
.WED...S wind 10 to 25 kt. Seas 9 to 17 ft.

$$

PKZ414-170215-
Bering Sea Offshore East of 171W-
317 AM AKST Sat Dec 16 2017

...GALE WARNING THROUGH SUNDAY...

.TODAY...N wind 25 to 40 kt. Seas 9 to 17 ft. Snow showers and rain 
showers.
.TONIGHT...NW wind 25 to 40 kt. Seas 13 to 21 ft. Snow and rain 
showers.
.SUN...W wind 20 to 35 kt. Seas 10 to 18 ft.
.SUN NIGHT...S wind 35 to 50 kt. Seas 10 to 18 ft.
.MON...SW wind 35 to 50 kt. Seas 14 to 22 ft.
.TUE...SW wind 20 to 30 kt. Seas 12 to 19 ft.
.WED...S wind 15 to 30 kt. Seas 10 to 16 ft.

$$

120 
FZAK62 PAFC 170002
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
302 PM AKST Sat Dec 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.

PKZ499-171415-
302 PM AKST Sat Dec 16 2017
.SYNOPSIS FOR CENTRAL BERING SEA...

A 977 mb low at 59N 166W becomes a 986 mb low near 57N 156W tonight 
and continues across the Gulf of Alaska for Mon afternoon. The 
associated front moves into the Eastern Bering Sun evening. A 985 mb 
Kamchatka low deepens to 949 mb Mon morning. Its associated front 
moves across the Bering and Aleutians by Mon afternoon.

$$

PKZ411-171415-
Bering Sea Offshore West of 180 and East of the International
Dateline-
302 PM AKST Sat Dec 16 2017

...STORM WARNING SUNDAY AND SUNDAY NIGHT...

.TONIGHT...SW wind 15 to 25 kt becoming S 25 to 40 kt after
midnight. Seas 8 to 13 ft.
.SUN...S wind 35 to 50 kt. Seas 11 to 19 ft building to 17 to 29
ft in the afternoon. Rain and snow.
.SUN NIGHT...SW wind 35 to 50 kt diminishing to 30 to 40 kt after
midnight. Seas 20 to 30 ft. Rain and snow showers.
.MON...SW wind 40 kt. Seas 22 to 29 ft.
.MON NIGHT...SW wind 35 to 45 kt. Seas 28 to 32 ft.
.TUE...W wind 25 to 40 kt. Seas 15 to 30 ft.
.WED THROUGH THU...W wind 10 to 25 kt. Seas 9 to 14 ft.

$$

PKZ412-171415-
Bering Sea Offshore 171W to 180 and North of 56N-
302 PM AKST Sat Dec 16 2017

...STORM WARNING SUNDAY NIGHT...

.TONIGHT...W wind 20 to 35 kt. Seas 9 to 17 ft.
.SUN...SW wind 15 to 30 kt becoming S 30 to 45 kt in the
afternoon. Seas 7 to 11 ft building to 9 to 17 ft in the afternoon. 
Snow and rain.
.SUN NIGHT...S wind 35 to 50 kt. Seas 13 to 28 ft building to 24
to 30 ft after midnight. Rain.
.MON...SW wind 25 to 40 kt. Seas 21 to 28 ft.
.MON NIGHT...SW wind 30 to 40 kt. Seas 20 to 30 ft.
.TUE...SW wind 25 to 40 kt. Seas 17 to 31 ft.
.WED...S wind up to 20 kt. Seas 8 to 13 ft.
.THU...W wind 10 to 25 kt. Seas 11 to 17 ft.

$$

PKZ413-171415-
Bering Sea Offshore 171W to 180 and South of 56N-
302 PM AKST Sat Dec 16 2017

...STORM WARNING SUNDAY AND SUNDAY NIGHT...

.TONIGHT...W wind 20 to 35 kt. Seas 10 to 17 ft.
.SUN...S wind 25 to 40 kt increasing to 35 to 50 kt in the
afternoon. Seas 12 to 20 ft. Rain.
.SUN NIGHT...S wind 40 to 55 kt. Seas 16 to 31 ft. Rain.
.MON...SW wind 30 to 45 kt. Seas 18 to 27 ft.
.MON NIGHT...SW wind 30 to 40 kt. Seas 18 to 29 ft.
.TUE...SW wind 20 to 35 kt. Seas 14 to 28 ft.
.WED...S wind 10 to 25 kt. Seas 9 to 17 ft.
.THU...W wind 15 to 30 kt. Seas 13 to 20 ft.

$$

PKZ414-171415-
Bering Sea Offshore East of 171W-
302 PM AKST Sat Dec 16 2017

...STORM WARNING SUNDAY NIGHT...

.TONIGHT...NW wind 30 to 40 kt. Seas 12 to 20 ft.
.SUN...W wind 20 to 35 kt. Seas 10 to 18 ft.
.SUN NIGHT...S wind 25 to 40 kt increasing to 35 to 50 kt after
midnight. Seas 8 to 13 ft building to 11 to 19 ft after midnight.
Rain.
.MON...S wind 35 to 50 kt. Seas 13 to 28 ft.
.MON NIGHT...SW wind 20 to 35 kt. Seas 13 to 21 ft.
.TUE THROUGH THU...S wind 20 to 35 kt. Seas 12 to 20 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
602 PM AKST Thu Dec 14 2017

.ANALYSIS AND UPPER LEVELS...

The broad upper trough which has been in place over the Bering Sea
and north-central Pacific for the past week is finally beginning
to break down and shift eastward. The main basal trough axis is
now shifting into the Gulf of Alaska this afternoon with a leading
edge shortwave trough moving north along the Gulf Coast. Satellite
imagery depicts a well defined anticyclonic deformation band
moving across Southcentral with a well defined area of moderate
precipitation over the North Gulf of Alaska spreading north into
Prince William Sound (as seen on the Middleton island radar).
There is an associated tight 987 mb surface low currently south of
the Copper River Delta. Over the Bering Sea, there is a broad low
972 mb low complex with one low center over the western Aleutians
and another lifting north just west of the Pribilof Islands.
South of the Aleutian Chain is where the main North Pacific jet
stream is, and there is another secondary basal low which will
eventually become a stronger low moving into Bristol Bay tonight.

&&

.MODEL DISCUSSION...
The models are in excellent agreement with the large scale
synoptic pattern, as usual, and are now coming into better
agreement with the smaller scale details as well. The biggest area
of model convergence has been toward the development of a single
stronger low in the vicinity of Bristol Bay and east of the
Pribilof Islands. Moreover, the models have trended toward one
another with a secondary low forming over the Gulf of Alaska, but
with this low being much weaker than what some models were hinting
at the last two days (a few GFS model runs were forming a powerful
957 hpa low near Kodiak Friday night). The GFS has now backed away
from that particular solution, but it is still the strongest model
solution, by far. The differences are subtle but important, with
the GFS and NAM forming a closed low over the North Gulf Coast
which would enhance both the precipitation as well as the barrier
jet. The ECMWF and Canadian models would favor a faster frontal
progression as well as stronger winds down Turnagain Arm...along
with less precipitation building inland on Saturday (likely in the
form of snow). For this forecast, a blend to the GFS and ECMWF was
favored which stuck to consistency but also taking into account
some of the details of the weaker/faster solutions.

&&

.AVIATION...
PANC...Light snow will spread into the terminal from the east
around 00-03z, lowering cigs below 5000 ft and possibly to MVFR
at times in CIGS and VIS. Conditions should then improve
overnight as the disturbance responsible for the snow showers
weakens and departs the region.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Snowfall intensity will pick up slightly across Anchorage and much
of the Mat-Su late this afternoon into evening as an upper level
short-wave trough moves up Cook Inlet, helping to pull some of
the deeper moisture from Prince William Sound westward. Weak low
level deformation will enhance snow amounts from about Wasilla
southeastward to Eagle River and on to east Anchorage and the
Hillside. In any case, expect light accumulation, with up to a
few inches. Snow will taper off overnight as the upper trough
continues to cross Southcentral. Meanwhile, notably heavier
precipitation will be over Western Prince William Sound where a
low is headed inland. Low level instability and upslope flow
behind this will keep showers going into the overnight hours.

Focus will then shift to a Gale force frontal boundary moving in
from the west on Friday. Expect high end Gales and moderate
precipitation as the front crosses the western Gulf and Kodiak
Island Friday morning. Precipitation may begin as snow, but will
quickly change to rain as warmer air arrives with the front. There
are some key differences in model guidance as to whether a triple
point low develops along the front Friday afternoon/evening. This
leads to a lower confidence forecast as the front approaches the
north Gulf coast and Kenai Peninsula late Friday. These differences
will affect speed of the front, extent of downsloping west of the
Kenai and Chugach Mountains, and precipitation type across the
Kenai Peninsula. For now, have gone with an intermediate solution
which depicts a weak low center, and focuses on the strong
easterly flow with the front. With a more southerly component to
the flow aloft, have maintained a chance of precip in the usual
downslope areas. Forecast confidence continues to drop Friday
night and Saturday due to uncertainties in triple point low as
well as the difficulty in timing upper level waves moving in
behind this system.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
(Tonight through Sunday evening)

The much-talked about storm is progressing towards the area, as
one strong low forms across the Bristol bay region. An attendant
front will sweep northeastward through the next 24 hours, with
widespread precipitation developing along it. Initially snow will
be the predominant precipitation type, some of which may be of
moderate intensity at times, which could reduce visibilities to
1/2 mile or less at times.

Snowfall accumulations will occur within the first 6 hours of it
beginning, right ahead of the front. With a tightening pressure
gradient, winds will gust in the 30 to 45 mph range across much of
the area, which may cause some blowing snow issues for a brief
period of time. eventually as the front continues its northward
journey, warmer air in the lowest few thousand feet of the
atmosphere will allow precipitation to change over to rain
following the frontal passage, while becoming more scattered on
coverage. Further south and west down the peninsula, the warmer
air will surge in quicker, with any snowfall accumulations minimal
before things quickly switch over to rain.

As this low moves north, a western Bering low will head
towards the peninsula for Saturday into Sunday, with disturbances
aloft rotating around it, continuing our precipitation chances.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
(Tonight through Sunday evening)

The forecast remains on track, with a 970 mb low spinning just
east of Shemya, with an attendant cold front currently near Adak.
As the front continues its eastward trek tonight, another
developing low will ride northward up the front from the North
Pacific. This low will deepen to 971 mb as it crosses western
portions of the AKpen tonight, before strengthening further as it
heads towards Nunivak Island Friday evening.

Widespread precipitation is likely ahead of the front, some of
which may be moderate to heavy at times for the central Aleutians
through the peninsula. For the near shore and open waters, gale
force winds will develop near both the advancing front and around
the periphery of the double-barrel low pressure systems.

&&

.LONG TERM FORECAST (Days 3 through 7...Sun through Thu)...
The long term will continue to see rather active weather, though
cooler (more seasonable) temperatures should move back in.
A fairly broad trough will slide through the area Sun into Mon.
There are several pieces of energy within this trough that could
produce precipitation. Let's start where there is the most
certainty...the Gulf Coast. A potent surface front and persistent
onshore flow will continue to keep things very wet from Seward
over to Yakutat. Gusty winds will also accompany the front.
Precipitation should be mostly rain right along the coast, but
inland just a short ways, there will be enough cold air
(especially over the higher terrain like Thompson Pass) to see the
rain turn to snow. Where there is less certainty is across Cook
Inlet. There is likely shot for some snow Sat night into Sun
morning. There is an outside chance that this snow could linger
into Sun a bit longer resulting in a few inches of accumulation.

Meanwhile on Sun into Mon over the Bering, a deep "bomb" cyclone
will develop. This will bring storm-force winds and rain/snow to
much of the Central and Western Aleutians. In response to this
system, a sharp short-wave ridge will build over the Eastern
Bering. This short-wave ridge will push quickly over the mainland
on Mon. It will have a little cold air to work with over Western
AK, so expect some gusty northwest winds to push through the
typical spots (Barren Islands, Shelikof Strait). The front
associated with the 950 mb "bomb" cyclone will slam into Western
AK late Mon into Tue. Precipitation will start as snow, but should
transition to rain across the southern portion of the area. Stay
tuned to this system as some of the initial snow could be quite
heavy.

Model uncertainty starts to b, mainly north and west of a Levelock
to Port Alsworth line. uild as this front slides towards South
Central AK. Some models depict it bringing a healthy shot of snow
to the Cook Inlet, while others show it washing out before it
makes it that far east. Then uncertainty really begins to increase
towards the end of the week. All models hint at a resurgence of
the North American Ridge (think weather pattern for first half of
Dec), which would once again allow a deep fetch of moisture and
warm air to move over the state from the N Pacific. Exactly where
the ridge sets up will be critical for nailing down sensible
weather at the surface.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 161.
MARINE...Storm warning 119. Gales 120 125 130 131 132 136 137 150
155 160 165 172-174 176-180 185 351 352 411 412.

&&

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