Storm Warning 172, NWS Anchorage, AK

353 
FZAK52 PAFC 271304
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
404 AM AKST Thu Dec 27 2018

Coastal Waters Forecast for Southwest Alaska+Bristol Bay+The
Alaska Peninsula Waters and the Aleutian Islands up to 100 nm out.

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.

PKZ199-280145-
404 AM AKST Thu Dec 27 2018
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A 993 mb low 180 nm southwest of Dutch Harbor will move over the
Alaska Peninsula at 998 mb Fri morning. The low will then move 
into the western Gulf Fri afternoon. A strong front will move 
over the western Aleutians Fri morning then it will move over the 
central Aleutians through Sat. The associated North Pacific low 
will move to 230 nm southwest of Adak at 950 mb Fri night then it
will move to 180 nm southeast of Shemya at 949 mb Sat morning.

$$

PKZ150-280145-
South of the AK Peninsula Sitkinak to Castle Cape-
404 AM AKST Thu Dec 27 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TODAY...SW wind 20 kt. Seas 11 ft.
.TONIGHT...S wind 20 kt. Seas 10 ft.
.FRI...S wind 20 kt becoming NW 30 kt in the afternoon. Seas 10 ft.
.FRI NIGHT...NW wind 30 kt. Seas 11 ft.
.SAT...S wind 35 kt. Seas 16 ft.
.SUN...S wind 30 kt. Seas 21 ft.
.MON...S wind 25 kt. Seas 21 ft.

$$

PKZ155-280145-
South of the AK Peninsula Castle Cape to Cape Sarichef-
404 AM AKST Thu Dec 27 2018

...GALE WARNING TONIGHT...

.TODAY...S wind 15 kt becoming E 25 kt in the afternoon. From the
Shumagin Islands E, SW wind 15 kt. Seas 12 ft. Rain and snow.
.TONIGHT...N wind 35 kt except SE 20 kt from the Shumagin Islands
E. Seas 11 ft. Rain and snow.
.FRI...NW wind 30 kt. Seas 10 ft.
.FRI NIGHT...W wind 25 kt. Seas 8 ft.
.SAT...S wind 40 kt. Seas 22 ft.
.SUN...S wind 30 kt. Seas 23 ft.
.MON...S wind 25 kt. Seas 19 ft.

$$

PKZ160-280145-
Bristol Bay-
404 AM AKST Thu Dec 27 2018

...HEAVY FREEZING SPRAY WARNING TONIGHT AND FRIDAY...
...SMALL CRAFT ADVISORY FRIDAY...

.TODAY...S wind 15 kt becoming W in the afternoon. Seas in ice
free waters 1 foot. Patchy freezing fog.
.TONIGHT...NW wind 20 kt. Seas in ice free waters 4 ft. Heavy
freezing spray near the ice edge and patchy freezing fog.
.FRI...NW wind 25 kt. Seas in ice free waters 8 ft. Heavy freezing 
spray near the ice edge.
.FRI NIGHT...NW wind 30 kt. Seas in ice free waters 9 ft.
.SAT...E wind 35 kt. Seas in ice free waters 6 ft.
.SUN...SE wind 30 kt. Seas in ice free waters 7 ft.
.MON...SE wind 20 kt. Seas in ice free waters 7 ft.

$$

PKZ165-280145-
Port Heiden to Cape Sarichef-
404 AM AKST Thu Dec 27 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TODAY...N wind 30 kt. From Port Moller E, variable wind less than 
10 kt becoming N 20 kt in the afternoon. Seas 8 ft.
.TONIGHT...N wind 25 kt. Seas 10 ft. Freezing spray.
.FRI...N wind 30 kt. Seas 10 ft. Freezing spray.
.FRI NIGHT...N wind 25 kt. Seas 9 ft.
.SAT...SE wind 40 kt. Seas 10 ft.
.SUN...SE wind 30 kt. Seas 10 ft.
.MON...S wind 20 kt. Seas 7 ft.

$$

PKZ170-280145-
Cape Sarichef to Nikolski Bering Side-
404 AM AKST Thu Dec 27 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TODAY...N wind 30 kt. Seas 12 ft.
.TONIGHT...N wind 30 kt. Seas 12 ft. Freezing spray.
.FRI...N wind 25 kt becoming NE 15 kt in the afternoon. Seas 9 ft.
Freezing spray.
.FRI NIGHT...SE wind 40 kt. Seas 8 ft.
.SAT...S wind 40 kt. Seas 13 ft.
.SUN...S wind 25 kt. Seas 13 ft.
.MON...S wind 20 kt. Seas 7 ft.

$$

PKZ171-280145-
Unalaska Bay-
404 AM AKST Thu Dec 27 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TODAY...N wind 10 kt increasing to 30 kt. Seas 7 ft building to 11 
ft in the afternoon. Snow and rain.
.TONIGHT...N wind 30 kt. Seas 11 ft. Freezing spray. Snow.
.FRI...N wind 25 kt diminishing to 15 kt in the afternoon. Seas 7
ft subsiding to 3 ft in the afternoon. Freezing spray.
.FRI NIGHT...SE wind 25 kt. Seas 4 ft.
.SAT...S wind 35 kt. Seas 5 ft.
.SUN THROUGH MON...S wind 15 kt. Seas 2 ft.

$$

PKZ172-280145-
Cape Sarichef to Nikolski Pacific Side-
404 AM AKST Thu Dec 27 2018

...GALE WARNING THROUGH TONIGHT...

.TODAY...N wind 35 kt. Seas 12 ft. Rain.
.TONIGHT...N wind 40 kt. Seas 13 ft. Rain.
.FRI...N wind 30 kt diminishing to 20 kt in the afternoon. 
Seas 10 ft.
.FRI NIGHT...SE wind 40 kt. Seas 10 ft.
.SAT...S wind 40 kt. Seas 23 ft.
.SUN THROUGH MON...S wind 25 kt. Seas 23 ft.

$$

PKZ173-280145-
Nikolski to Seguam Island Bering Side-
404 AM AKST Thu Dec 27 2018

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TODAY...N wind 30 kt. Seas 12 ft.
.TONIGHT...N wind 25 kt. Seas 10 ft.
.FRI...NE wind 15 kt becoming SE 25 kt in the afternoon. Seas 8 ft.
.FRI NIGHT...SE wind 45 kt. Seas 18 ft.
.SAT...S wind 40 kt. Seas 18 ft.
.SUN...S wind 15 kt. Seas 12 ft.
.MON...SW wind 20 kt. Seas 10 ft.

$$

PKZ174-280145-
Nikolski to Seguam Island Pacific Side-
404 AM AKST Thu Dec 27 2018

...GALE WARNING TODAY...

.TODAY...N wind 35 kt. Seas 15 ft.
.TONIGHT...N wind 30 kt. Seas 13 ft.
.FRI...NE wind 15 kt becoming SE 25 kt in the afternoon. 
Seas 8 ft.
.FRI NIGHT...SE wind 45 kt. Seas 22 ft.
.SAT...S wind 35 kt. Seas 25 ft.
.SUN...S wind 20 kt. Seas 25 ft.
.MON...SW wind 20 kt. Seas 21 ft.

$$

PKZ175-280145-
Seguam Island to Adak Bering Side-
404 AM AKST Thu Dec 27 2018

...GALE WARNING FRIDAY...

.TODAY...N wind 25 kt. Seas 10 ft.
.TONIGHT...N wind 20 kt becoming E 15 kt after midnight. Seas 8 ft.
.FRI...SE wind 30 kt increasing to 40 kt in the afternoon. Seas
10 ft. Rain.
.FRI NIGHT...SE wind 45 kt. Seas 19 ft.
.SAT...S wind 30 kt. Seas 15 ft.
.SUN...S wind 25 kt. Seas 10 ft.
.MON...W wind 20 kt. Seas 10 ft.

$$

PKZ176-280145-
Seguam Island to Adak Pacific Side-
404 AM AKST Thu Dec 27 2018

...GALE WARNING FRIDAY...

.TODAY...N wind 30 kt. Seas 12 ft.
.TONIGHT...N wind 20 kt becoming E after midnight. Seas 9 ft.
.FRI...SE wind 30 kt increasing to 45 kt in the afternoon. Seas 7
ft building to 15 ft in the afternoon. Rain.
.FRI NIGHT...SE wind 45 kt. Seas 25 ft.
.SAT...S wind 35 kt. Seas 32 ft.
.SUN...S wind 20 kt. Seas 25 ft.
.MON...W wind 20 kt. Seas 18 ft.

$$

PKZ177-280145-
Adak to Kiska-
404 AM AKST Thu Dec 27 2018

...GALE WARNING TONIGHT AND FRIDAY...

.TODAY...N wind 20 kt becoming E in the afternoon. Seas 9 ft.
.TONIGHT...E wind 25 kt becoming SE 45 kt after midnight. Seas 6
ft building to 11 ft after midnight.
.FRI...E wind 45 kt. Seas 21 ft. Rain and snow.
.FRI NIGHT...SE wind 50 kt. Seas 33 ft.
.SAT...S wind 40 kt. Seas 37 ft.
.SUN...S wind 30 kt. Seas 26 ft.
.MON...W wind 25 kt. Seas 14 ft.

$$

PKZ178-280145-
Kiska to Attu-
404 AM AKST Thu Dec 27 2018

...HURRICANE FORCE WIND WARNING TONIGHT...

.TODAY...E wind 15 kt increasing to 30 kt in the afternoon. 
Seas 8 ft.
.TONIGHT...SE wind 35 kt becoming E 65 kt after midnight. Bering 
side, seas 9 ft building to 20 ft after midnight. Pacific side, seas 
15 ft building to 30 ft after midnight. Widespread snow showers.
.FRI...E wind 55 kt diminishing to 45 kt in the afternoon. Seas
31 ft subsiding to 24 ft in the afternoon. Widespread snow showers
and rain.
.FRI NIGHT...NE wind 55 kt. Seas 36 ft.
.SAT...NE wind 60 kt. Seas 38 ft.
.SUN...NE wind 35 kt. Seas 25 ft.
.MON...NW wind 20 kt. Seas 18 ft.

$$

PKZ179-280145-
Pribilof Islands Near Shore Waters-
404 AM AKST Thu Dec 27 2018

.TODAY...N wind 20 kt. Seas 7 ft. Freezing spray.
.TONIGHT...N wind 20 kt. Seas 7 ft. Freezing spray.
.FRI...N wind 15 kt. Seas 5 ft. Freezing spray.
.FRI NIGHT...NE wind 25 kt. Seas 5 ft.
.SAT...SE wind 45 kt. Seas 16 ft.
.SUN...SE wind 20 kt. Seas 16 ft.
.MON...Variable wind 10 kt. Seas 10 ft.

$$

PKZ180-280145-
Kuskokwim Delta and Etolin Strait-
404 AM AKST Thu Dec 27 2018

...HEAVY FREEZING SPRAY WARNING THROUGH FRIDAY...
...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TODAY...N wind 25 kt. Seas in ice free waters 5 ft. 
Heavy freezing spray near the ice edge.
.TONIGHT...NW wind 25 kt. Seas in ice free waters 6 ft. 
Heavy freezing spray.
.FRI...N wind 30 kt. Seas in ice free waters 6 ft. 
Heavy freezing spray.
.FRI NIGHT...N wind 25 kt. Seas in ice free waters 5 ft.
.SAT...E wind 40 kt. Seas in ice free waters 12 ft.
.SUN...SE wind 35 kt. Seas in ice free waters 12 ft.
.MON...SE wind 20 kt. Seas in ice free waters 7 ft.

$$

PKZ181-280145-
North and West of Nunivak Island-
404 AM AKST Thu Dec 27 2018

.TODAY...N wind 20 kt.
.TONIGHT...N wind 20 kt.
.FRI...N wind 15 kt.
.FRI NIGHT...N wind 15 kt.
.SAT...NE wind 40 kt.
.SUN...E wind 35 kt.
.MON...E wind 15 kt.

$$

PKZ185-280145-
Saint Matthew Island Waters-
404 AM AKST Thu Dec 27 2018

...HEAVY FREEZING SPRAY WARNING THROUGH FRIDAY...

.TODAY...N wind 20 kt. Seas 7 ft. Heavy freezing spray.
.TONIGHT...N wind 20 kt. Seas 7 ft. Heavy freezing spray.
.FRI...N wind 20 kt. Seas 6 ft. Heavy freezing spray.
.FRI NIGHT...NE wind 30 kt. Seas 6 ft.
.SAT...NE wind 45 kt. Seas 23 ft.
.SUN...NE wind 40 kt. Seas 23 ft.
.MON...NE wind 25 kt. Seas 12 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
438 AM AKST Wed Dec 26 2018

.ANALYSIS AND UPPER LEVELS...

A vertically stacked low spins in the southeastern Gulf this
morning. The low sits at the base of a long wave trough that
encompasses much of western mainland Alaska, AKPEN and Gulf.
Within the flow of the trough, there are several short waves
present, one of which is over the AKPEN with a vertically stacked
low at the base. The jet stream is in a meridional pattern with
the ridge sitting south of the AKPEN and and the trough extending
into the eastern Gulf. With the surface low sitting in the left
exit region of the jet and a band of vorticity extending from the
low center, a deformation zone has established itself over Kodiak
Island. This deformation zone combined with the influx of
moisture is bringing precipitation to the northern Gulf and the
Kenai Peninsula. Water vapor satellite imagery shows the edge of
the band well, extending from Bristol Bay over Kodiak Island.
Southcentral however, remains dry as a deep layer of dry air and
easterly winds are creating challenging conditions for the
precipitation to reach the surface. In the west, instability is
increasing throughout Bristol Bay along the deformation zone. The
instability with the addition of moisture from the Gulf is
initiating snow bands through the Lower Kuskokwim Valley. The
Bering is still sitting under high pressure which is keeping the
cold air in place with persistent east to northeasterly flow.

&&

.MODEL DISCUSSION...

Models continue to agree early on through Thursday morning
regarding a North Pacific low moving into the southwestern Gulf
Thursday and a low pressure system south of the central Aleutians.
As the low enters the Gulf, the NAM is the most northern track
(closer to Kodiak Island) and the EC is the most southern. The GFS
is splitting the center while the Canadian is off in the middle
of the Gulf. By Thursday afternoon, models diverge even further
with the NAM and GFS setting up over the northwestern Gulf south
of the Kenai Peninsula, and the EC and Canadian moving into the
northeastern Gulf. Friday, the models all agree that the system
will move inland over Prince William Sound. While the models all
take this low on different paths, the meteorological outcomes are
not going to be too significantly different. With this system, a
GFS/NAM combination was used. Regarding the low in the North
Pacific south of the chain, models continue to split with the NAM
being the fastest solution and the GFS being the slowest.

&&

.AVIATION...

PANC...VFR conditions with light north to northeast winds will
prevail through tonight. A weak shortwave trough lifting north
over the area this evening, however, will bring a chance for
brief light snow showers.

&&

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

The old front has stalled over the southern Kenai Peninsula and is
bringing rain and snow to the area. The front will continue to
diminish through today and eventually be pushed north as a short
wave moves in from the south this afternoon. As it does there is a
chance for areas around Cook Inlet and north into the Mat-Su
Valleys to see some showers. Tonight a new system will approach
the Gulf from the North Pacific bringing a strong push of warm air
with it. However, models are still struggling somewhat with the
track of the system as it approaches the north Gulf coast Thursday
afternoon which will play a factor in what areas see the most
precipitation and what type of precipitation will fall for those
areas. Most of the guidance seems confident that the Anchorage
area will see some snow Thursday afternoon/evening but the amounts
will be a challenge until the models get a better handle on the
low position.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Friday)...

Just when there was the potential for some active weather across
Southwest Alaska, it turns out things are going to remain
relatively quiet for a while longer. King Salmon radar is showing
weak echoes associated with a snow band that extends north from
near Iliamna into the Lower Kuskokwim Valley. Radar returns and
observations so far have been underwhelming to say the least,
thus, the forecast for today has lowered snowfall totals in that
area to an inch or two. Any snow showers associated with the band
will lift northward this afternoon and dissipate tonight.

Utilization of the models shows a weak front expected to impact
portions of Bristol Bay starting late tonight and into Thursday
morning. These snow showers will be enhanced by an approaching
upper level low. Even though the surface front is likely to
dissipate as it moves inland during the day, the approaching
upper level low should help to produce scattered to widespread
snow showers over most of Southwest Alaska Thursday into Thursday
night.

Lastly, an upper level shortwave circulating around the low will
move into the Kuskokwim Delta late Thursday night, though the
upper level front will extend much further south from there.
Meanwhile, a surface low is expected to develop on the south side
of the Alaska Peninsula Thursday night, which will be forced by
the same upper level front. This feature will help to enhance the
moisture transport into Southwest Alaska during the day Friday.
Thus, the combination of the approaching upper level low and
shortwave may result in the development of steadier snow across
Bristol Bay and the Lower Kuskokwim Valley. Chances of snow have
been raised to likely for the day on Friday, though amounts for
now are generally looking to be light, in the 1 to 3 inch range.
Much colder air associated with the upper level low itself returns
to Southwest Alaska behind this feature Friday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today
through Friday)...

Inherently quiet weather continues across much of the Bering Sea
this morning as continuous north to northeasterly winds persist.
As we have been seeing for a couple weeks now, this is resulting
in widespread stratus with the flow remaining generally cyclonic,
as the cold air moves over the relatively warm Bering, resulting
in the cloudiness. This pattern is likely to persist right through
Thursday night for most of the area. A generally weak, slow moving
low south of the central Aleutians is expected to continue moving
east with time, brushing the Eastern Aleutians and Alaska
Peninsula by Thursday night. In those areas, there may be brief
periods of steadier snow showers, but no significant weather is
expected from it.

All of that will change late Thursday night into Friday across the
western Aleutians. All of the models are showing a very strong,
moisture-laden storm system ramping up over the Northwest Pacific
and moving into the Western Aleutians early Friday morning and the
Central Aleutians Friday afternoon. Very strong winds look to be
the key hazard with this, as otherwise relatively warm air should
keep most areas that get precipitation with this feature as mostly
rain. The models have been very consistent with the development of
this strong front and associated lows behind it, though as usual,
the timing and consistency of those models remains very
changeable. That said, it now appears at least storm force winds
are likely across a large area including the Western and Central
Aleutians, which given current model trends may go higher with
time. Interests in this area should keep close watch to future
forecasts as this system has the potential to require future
watches and warnings to need to be issued.

&&

.LONG TERM FORECAST (Days 3 through 7...Fri Dec 28 through Tue Jan
1)...

The extended forecast still features a very active weather pattern
across the entire area. Models continue to advertise a fast-moving
SW-NE storm track from the North Pacific into SW AK. The major
shift from yesterday is that the ECMWF has backed off on how
strong it builds the ridge over the ALCAN Border by early next
week. Yesterday, the EC and GEM (Canadian) were advertising a
strong high-amplitude ridge building along the ALCAN Border. This
would have set up a very meridional pattern going in to next week.
However, the EC has now trended towards the GFS which would
yield a colder forecast with several modest storms moving quickly
through the pattern.

With that much uncertainty between models and even from run to run
within a model, the forecast for next week is highly uncertain at
this time. The few things we can lock onto though are late this
week and into the weekend. The deep, cold trough digging down from
the Bering Strait into the North Pacific will be sure to push some
snow showers over the Alaska Peninsula. These will favor the north
side of the chain. For the marine zones south of the peninsula,
expect gusty winds through bays and passes into very early Sat
morning. There is also high certainty with a deep (possible
mid-940 mb range) low developing over the Western Aleutians Sat
morning. The associated front will bring a healthy area of gale-
storm force south to southeast winds. It will also push a good
amount of warm air up into the chain. So while precipitation could
start as heavy snow, it will quickly transition into heavy rain.

Along this front will be the primary forecast challenge. There
will be triple point lows forming along this occluded boundary.
But trying to nail down exact timing, placement, or strength of
these lows is a fool's errand at this time. Each one of these
systems will have the potential to bring a surge of warm air into
the mainland with it. However, we will not start investigating any
specific system until the models have come into better agreement
regarding the upper levels (ALCAN ridge) first.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gales 119 120 131 132 173 174.
         Heavy Freezing Spray 180 181 185.

&&

SYNOPSIS AND MODEL DISCUSSION...RA/JER
SOUTHCENTRAL ALASKA...DK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JW
LONG TERM...MSO