Storm Warning 195, NWS Anchorage, AK

175 
FZAK52 PAFC 230021
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
321 PM AKST Sun Dec 22 2019

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.

PKZ199-231315-
321 PM AKST Sun Dec 22 2019
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A 967 mb low 115 nm southeast of Saint Paul Sun afternoon moves 50
nm south of King Salmon at 976 mb Mon afternoon. A 989 mb low 
450 nm southwest of Adak Mon afternoon moves 220 nm southwest of 
Dutch Harbor at 973 mb Tue afternoon.

$$

PKZ150-231315-
South of the AK Peninsula Sitkinak to Castle Cape-
321 PM AKST Sun Dec 22 2019

...GALE WARNING THROUGH MONDAY...

.TONIGHT...SW wind 35 kt increasing to 45 kt after midnight. 
Seas 18 ft building to 25 ft after midnight. Rain.
.MON...SW wind 45 kt diminishing to 30 kt in the afternoon. 
Seas 28 ft. Rain.
.MON NIGHT...W wind 30 kt. Seas 18 ft.
.TUE...W wind 30 kt. Seas 18 ft.
.TUE NIGHT...NE wind 30 kt. Seas 10 ft.
.WED...NW wind 45 kt. Seas 21 ft.
.THU...NW wind 40 kt. Seas 15 ft.
.FRI...NW wind 30 kt. Seas 9 ft.

$$

PKZ155-231315-
South of the AK Peninsula Castle Cape to Cape Sarichef-
321 PM AKST Sun Dec 22 2019

...STORM WARNING TONIGHT...

.TONIGHT...SW wind increasing to 50 kt. Seas 38 ft. From the 
Shumagin Islands E, seas 25 ft building to 33 ft after midnight. 
Rain and snow.
.MON...W wind 40 kt. From the Shumagin Islands E, SW wind 45 kt
becoming W 25 kt in the afternoon. Seas 30 ft subsiding to 22 ft
in the afternoon.
.MON NIGHT...NW wind 35 kt. Seas 21 ft.
.TUE...N wind 35 kt. Seas 16 ft.
.TUE NIGHT...NE wind 45 kt. Seas 16 ft.
.WED...NW wind 45 kt. Seas 19 ft.
.THU...NW wind 35 kt. Seas 12 ft.
.FRI...N wind 20 kt. Seas 11 ft.

$$

PKZ160-231315-
Bristol Bay-
321 PM AKST Sun Dec 22 2019

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...SE wind 25 kt. Seas 8 ft. Snow and rain showers.
.MON...N wind 30 kt. Seas 8 ft. Freezing spray.
.MON NIGHT...NW wind 30 kt. Seas 10 ft. Freezing spray.
.TUE...NW wind 30 kt. Seas 10 ft.
.TUE NIGHT...NE wind 25 kt. Seas 5 ft.
.WED THROUGH THU...NW wind 30 kt. Seas 9 ft.
.FRI...N wind 20 kt. Seas 5 ft.

$$

PKZ165-231315-
Port Heiden to Cape Sarichef-
321 PM AKST Sun Dec 22 2019

...STORM WARNING TONIGHT...

.TONIGHT...SW wind increasing to 50 kt, Seas 32 ft. From Port Moller
E, S wind 30 kt becoming SW 40 kt after midnight, Seas 15 ft 
building to 21 ft after midnight. Widespread rain and snow showers.
.MON...W wind 30 kt. Seas 22 ft subsiding to 15 ft in the
afternoon.
.MON NIGHT...NW wind 30 kt. Seas 14 ft.
.TUE...N wind 25 kt. Seas 11 ft.
.TUE NIGHT...NE wind 35 kt. Seas 11 ft.
.WED...NW wind 35 kt. Seas 13 ft.
.THU...N wind 30 kt. Seas 12 ft.
.FRI...N wind 20 kt. Seas 8 ft.

$$

PKZ170-231315-
Cape Sarichef to Nikolski Bering Side-
321 PM AKST Sun Dec 22 2019

...STORM WARNING TONIGHT...

.TONIGHT...W wind 60 kt diminishing to 50 kt after midnight. 
Seas 43 ft subsiding to 34 ft after midnight. Rain.
.MON...W wind 45 kt diminishing to 35 kt in the afternoon. 
Seas 24 ft. Rain showers.
.MON NIGHT...NW wind 30 kt diminishing to 15 kt after midnight.
Seas 18 ft.
.TUE AND TUE NIGHT...N wind 35 kt. Seas 12 ft.
.WED...NW wind 30 kt. Seas 12 ft.
.THU...NE wind 20 kt. Seas 8 ft.
.FRI...NE wind 15 kt. Seas 10 ft.

$$

PKZ171-231315-
Unalaska Bay-
321 PM AKST Sun Dec 22 2019

...GALE WARNING TONIGHT...

.TONIGHT...W wind 40 kt diminishing to 30 kt after midnight. 
Seas 6 ft. Snow.
.MON...W wind 30 kt. Gusts to 40 kt. Seas 5 ft building to 10 ft in 
the afternoon. Rain showers and snow showers.
.MON NIGHT...NW wind 25 kt becoming W 10 kt after midnight. 
Seas 10 ft subsiding to 2 ft after midnight.
.TUE...NE wind 30 kt. Seas 7 ft.
.TUE NIGHT...N wind 35 kt. Seas 12 ft.
.WED...NW wind 30 kt. Seas 11 ft.
.THU...NE wind 15 kt. Seas 5 ft.
.FRI...NE wind 10 kt. Seas 3 ft.

$$

PKZ172-231315-
Cape Sarichef to Nikolski Pacific Side-
321 PM AKST Sun Dec 22 2019

...STORM WARNING THROUGH MONDAY...

.TONIGHT...W wind 55 kt diminishing to 45 kt after midnight. 
Seas 40 ft subsiding to 28 ft after midnight. Snow and rain.
.MON...W wind 50 kt diminishing to 40 kt in the afternoon. 
Seas 25 ft.
.MON NIGHT...W wind 35 kt diminishing to 20 kt after midnight.
Seas 23 ft subsiding to 16 ft after midnight.
.TUE...E wind 45 kt. Seas 12 ft.
.TUE NIGHT...N wind 50 kt. Seas 19 ft.
.WED...NW wind 40 kt. Seas 17 ft.
.THU...NE wind 25 kt. Seas 11 ft.
.FRI...NE wind 15 kt. Seas 19 ft.

$$

PKZ173-231315-
Nikolski to Seguam Island Bering Side-
321 PM AKST Sun Dec 22 2019

...STORM WARNING THROUGH MONDAY...

.TONIGHT...W wind 55 kt diminishing to 40 kt after midnight. 
Seas 41 ft subsiding to 26 ft after midnight.
.MON...W wind 50 kt diminishing to 35 kt in the afternoon. 
Seas 29 ft subsiding to ft in the afternoon.
.MON NIGHT...W wind 30 kt in the evening becoming variable 10 kt.
Seas 18 ft subsiding to 13 ft after midnight.
.TUE...NE wind 40 kt. Seas 12 ft.
.TUE NIGHT...N wind 30 kt. Seas 12 ft.
.WED...N wind 20 kt. Seas 10 ft.
.THU...E wind 25 kt. Seas 9 ft.
.FRI...E wind 15 kt. Seas 16 ft.

$$

PKZ174-231315-
Nikolski to Seguam Island Pacific Side-
321 PM AKST Sun Dec 22 2019

...STORM WARNING TONIGHT...

.TONIGHT...W wind 50 kt diminishing to 40 kt after midnight. Seas
39 ft subsiding to 26 ft after midnight. Rain and snow.
.MON...W wind 45 kt diminishing to 35 kt in the afternoon. Seas 26 
ft subsiding to 21 ft in the afternoon.
.MON NIGHT...W wind 30 kt becoming SE after midnight. Seas 20 ft
subsiding to 14 ft after midnight.
.TUE...NE wind 45 kt. Seas 16 ft.
.TUE NIGHT...N wind 40 kt. Seas 18 ft.
.WED...N wind 25 kt. Seas 13 ft.
.THU...E wind 25 kt. Seas 16 ft.
.FRI...E wind 15 kt. Seas 20 ft.

$$

PKZ175-231315-
Seguam Island to Adak Bering Side-
321 PM AKST Sun Dec 22 2019

...GALE WARNING THROUGH MONDAY...

.TONIGHT...W wind 45 kt. Seas 29 ft subsiding to 22 ft after
midnight.
.MON...W wind 45 kt diminishing to 30 kt in the afternoon. 
Seas 23 ft subsiding to 17 in the afternoon.
.MON NIGHT...NW wind 25 kt becoming N 15 kt after midnight. 
Seas 14 ft.
.TUE AND TUE NIGHT...NW wind 30 kt. Seas 11 ft.
.WED...NE wind 25 kt. Seas 8 ft.
.THU...E wind 30 kt. Seas 8 ft.
.FRI...E wind 20 kt. Seas 14 ft.

$$

PKZ176-231315-
Seguam Island to Adak Pacific Side-
321 PM AKST Sun Dec 22 2019

...GALE WARNING THROUGH MONDAY...

.TONIGHT...NW wind 40 kt. Seas 26 ft. Rain and snow.
.MON...W wind 40 kt diminishing to 30 kt in the afternoon. Seas
21 ft.
.MON NIGHT...N wind 20 kt becoming NE 30 kt after midnight. Seas
13 ft.
.TUE...N wind 40 kt. Seas 14 ft.
.TUE NIGHT...NW wind 35 kt. Seas 15 ft.
.WED...NE wind 30 kt. Seas 11 ft.
.THU...E wind 35 kt. Seas 15 ft.
.FRI...E wind 15 kt. Seas 18 ft.

$$

PKZ177-231315-
Adak to Kiska-
321 PM AKST Sun Dec 22 2019

...GALE WARNING THROUGH MONDAY...

.TONIGHT...W wind 30 kt increasing to 40 kt after midnight. 
Seas 19 ft.
.MON...W wind 35 kt becoming NW 25 kt in the afternoon. 
Seas 18 ft.
.MON NIGHT...N wind 25 kt. Seas 11 ft.
.TUE AND TUE NIGHT...NW wind 30 kt. Seas 12 ft.
.WED...E wind 35 kt. Seas 13 ft.
.THU...E wind 35 kt. Seas 17 ft.
.FRI...E wind 20 kt. Seas 15 ft.

$$

PKZ178-231315-
Kiska to Attu-
321 PM AKST Sun Dec 22 2019

...GALE WARNING TONIGHT...

.TONIGHT...W wind 35 kt. Seas 16 ft. Freezing spray.
.MON...W wind 30 kt becoming NW 20 kt in the afternoon. 
Seas 15 ft. Freezing spray.
.MON NIGHT...NW wind 15 kt. Seas 11 ft.
.TUE...NW wind 15 kt. Seas 9 ft.
.TUE NIGHT...N wind 25 kt. Seas 10 ft.
.WED...E wind 40 kt. Seas 20 ft.
.THU...SE wind 35 kt. Seas 20 ft.
.FRI...E wind 25 kt. Seas 16 ft.

$$

PKZ179-231315-
Pribilof Islands Near Shore Waters-
321 PM AKST Sun Dec 22 2019

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...NE wind 30 kt. Seas 21 ft. Snow and widespread 
rain showers.
.MON...N wind 25 kt. Seas 16 ft.
.MON NIGHT...NW wind 15 kt. Seas 12 ft. Freezing spray.
.TUE...NE wind 20 kt. Seas 9 ft.
.TUE NIGHT...N wind 25 kt. Seas 7 ft.
.WED...N wind 20 kt. Seas 8 ft.
.THU...NE wind 15 kt. Seas 6 ft.
.FRI...NE wind 15 kt. Seas 11 ft.

$$

PKZ180-231315-
Kuskokwim Delta and Etolin Strait-
321 PM AKST Sun Dec 22 2019

...SMALL CRAFT ADVISORY THROUGH MONDAY NIGHT...

.TONIGHT...E wind 30 kt. Seas 14 ft. Freezing spray N of Cape
Newenham. Snow and rain showers.
.MON...N wind 25 kt. Seas 12 ft. Freezing spray.
.MON NIGHT...NW wind 30 kt. Seas 10 ft. Freezing spray.
.TUE...N wind 30 kt. Seas 8 ft.
.TUE NIGHT...N wind 25 kt. Seas 5 ft.
.WED...N wind 35 kt. Seas 10 ft.
.THU...N wind 30 kt. Seas 9 ft.
.FRI...N wind 20 kt. Seas 5 ft.

$$

PKZ181-231315-
North and West of Nunivak Island-
321 PM AKST Sun Dec 22 2019

...GALE WARNING TONIGHT...
...HEAVY FREEZING SPRAY WARNING THROUGH MONDAY NIGHT...

.TONIGHT...NE wind 35 kt. Seas 12 ft. Heavy freezing spray.
.MON...N wind 30 kt. Seas 12 ft. Heavy freezing spray.
.MON NIGHT...N wind 25 kt. Seas 8 ft. Heavy freezing spray.
.TUE...N wind 25 kt. Seas 8 ft.
.TUE NIGHT...N wind 20 kt. Seas 7 ft.
.WED...N wind 25 kt. Seas 7 ft.
.THU THROUGH FRI...NE wind 20 kt. Seas 6 ft.

$$

PKZ185-231315-
Saint Matthew Island Waters-
321 PM AKST Sun Dec 22 2019

...GALE WARNING TONIGHT...

.TONIGHT...NE wind 35 kt. Seas 19 ft. Freezing spray.
.MON...NE wind 30 kt. Seas 14 ft. Freezing spray.
.MON NIGHT...NE wind 25 kt. Seas 10 ft. Freezing spray.
.TUE AND TUE NIGHT...N wind 20 kt. Seas 8 ft.
.WED...N wind 20 kt. Seas 7 ft.
.THU THROUGH FRI...NE wind 25 kt. Seas 9 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
359 PM AKST Sat Dec 21 2019

.ANALYSIS AND UPPER LEVELS...
A vertically stacked storm force low continues to strengthen as it
lifts northward across the western Aleutian and into the southern
Bering Sea. The frontal system is tracking north and east from
the low center across the Bering Sea and Aleutian chain. Widespread
gale to storm force winds are being observed across the region
along with rain and snow. A trailing short-wave trough is tracking
eastward, leading to strong cold air advection across the far
western Bering Sea. This colder air is beginning to feed into the
back side of the storm system which is strengthening winds even
more. Expect hurricane force winds to develop along and near the
western Aleutians late this afternoon through this evening.
Precipitation will also change from rain to snow, though surface
temperatures near freezing will limit visibility reductions.

Meanwhile, an upper level short-wave trough is tracking eastward
across Southwest Alaska and headed for Southcentral. With a cold
and dry air mass in place, this trough is coming through mostly
dry, with just a few areas of flurries or light snow over the
Kuskokwim Valley. There are some mid to high level clouds out
ahead of the trough which are helping to keep temperatures a bit
warmer than they otherwise would be. Still, temperatures are in
the single digits to teens across most of the southern mainland
of Alaska.

Low level cold air advection accompanies the upper trough,
particularly along the south end of the trough from Bristol Bay
to the Gulf. This is leading to strong westerly winds across the
western Gulf and Kodiak Island coastal waters. This is also
helping maintain offshore gap winds along the north Gulf coast
and Prince William Sound.

&&

.MODEL DISCUSSION...
Models are in fair agreement with key large scale features. There
is a split in solutions with track of the Bering low on Monday,
with the NAM/GFS stalling the low in Bristol Bay and the
ECMWF/Canadian tracking it across the Alaska Peninsula into the
western Gulf. This will greatly affect the precipitation and wind
forecast for the Bristol Bay and Alaska Peninsula area. For now,
will stick with current forecast which favors the NAM/GFS idea
of bringing another round of precipitation and wind to Bristol
Bay.

Solutions also diverge on Tuesday with whether a short-wave moving
out of Southwest Alaska phases with a trough over the Gulf. The
12Z NAM is the current outlier with development of a closed low
over the Gulf and maintaining two completely separate troughs.
The rest of the solutions indicate some aspect of phasing as the
troughs lift northward toward Southcentral. This latter idea would
lead to greater potential for a snowstorm in the Anchorage area
sometime in the Tuesday to Wednesday time frame.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Offshore flow will continue bring cold temperatures across much
of Southcentral. Although an upper level trough will track across
the region Sunday morning, it should depart eastward fast enough
for skies to clear before sunrise, thus dropping low temperatures
to near zero in Anchorage. Clouds will again increase through the
day Sunday with light snow developing in the afternoon over the
Kenai Peninsula and Prince William Sound. Though accumulations are
not expected to be significant (1 to 3 inches possible along the
Seward highway between Girdwood and Seward), brief periods of
blowing snow with reduced visibility are likely early Monday
morning in Turnagain Pass.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Cold temperatures will persist through Sunday night across all of
southwest Alaska. The main item of interest will be an
approaching front that's attached to a strong Bering Sea low.
This low approaches the coast for Sunday. Increasing wind speeds
and snow developing will proceed the front, with the strongest
winds expected along the northern portion of the Bristol Bay
coast from Cape Newenham eastward to Dillingham. Here, winds
gusting up to 35 mph combined with snowfall will likely reduce the
visibility at times. However, the numerical models still disagree
with the track of the Bering low, as the NAM, GFS, and GFS
ensemble models take this low across northern portions of the bay,
while the Canadian global and ECMWF take the low into the Alaska
Peninsula. The latter solution would decrease the snowfall amount
and blowing snow potential. Stay tuned.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A strong Bering Sea low continues to slowly deepen and passes to
the northwest of Amchitka this afternoon. The latest satellite
loops show this nicely, as the infra-red shows cooling cloud tops
on the backside of the low, as additional shortwave energy dives
into the base of the associated trough from Siberia. Visible
imagery shows the destabilizing effects of the colder air wrapping
into the system as the upper-level disturbance gets ingested,
with a few TCU (towering cumulus)-like features noted in the
latest loops. This is of no surprise though, given ocean delta-Ts
approaching 15 deg. C in the surface to 850 mb (~4400 feet), with
model estimates on soundings of MUCAPEs of 100-150 J/kg.

Thus, sufficient instability exists for good vertical growth in
the backside of the low, with perhaps a flash or two of lightning
not out of the question. The more important concern is with this
type of instability, given the amount of lift/upward motion
associated with this low, as colder (heavier) air invades the
region you enhance the potential of mixing the stronger winds
aloft down to the surface. With that in mind, we increased the
winds for much of the Bering Sea and Aleutians for tonight and
Sunday, before the storm slowly weakens by Sunday night as it
becomes more vertically stacked.

At this time, the current high wind warning headlines look good.
We'll need to keep an eye on the observational and model trends
though, as the Nikolski and Dutch Harbor/Unalaska areas will be
right near warning level thresholds.

&&

.MARINE (Days 3 through 5: Tuesday through Thursday)...
Tuesday will be the quietest of the extended period days for
Southern Alaska waters as a whole, with no strong features to
speak of. A weak spinoff triple-point low will be over the western
Gulf, the last remnants of the giant hurricane force low
currently out over the Bering. Thus, save for some small craft
winds south of this low the Gulf will be quiet on Tuesday.

Meanwhile a developing North Pacific low will begin producing gale
force winds north of the low center on the Pacific side of the
Alaska Peninsula and eastern Aleutians Tuesday afternoon. The low
will strengthen as it moves into the southwestern Gulf Wednesday
morning, producing storm force winds on the west side of the
center. It strengthens even further as it moves to between Kodiak
and Middleton Island Wednesday evening. There are some model
differences, but barrier jet winds to hurricane force are not
outside the realm of possibility at this time. Regardless of local
hurricane force winds, widespread storm force winds are likely
over large swatch of the Gulf starting Wednesday afternoon and
continuing into Thursday with the return flow behind the low.
Storm force winds persist through the day Thursday through the
Barren Islands, with widespread gales across the central and
southern Gulf.

A separate gale force front will move into the western Aleutians
on Wednesday. While it will maintain its strength through
Thursday, it will stall out its movement over the central Bering,
and thus, impacts from the front should be minimal.

&&

.LONG TERM FORECAST (Days 3 through 7: Tuesday through Saturday)...
A very interesting, active weather pattern is in store across the
Southern mainland through the long term. Uncertainty begins right
from the get-go. A deep polar upper level trough will be over
Southwest Alaska Tuesday morning. An associated shortwave trough
extending southeastward from the low will attempt to phase with a
second upper level low over the far southern Gulf. The models are
in poor agreement as to how much phasing occurs. The better the
phasing, the more likely accumulating snow across Southcentral,
including Anchorage, will be. Snow lovers will like the EC, which
begins steady snow as early as Monday evening. The rest of the
models aren't quite as bullish with the moisture until Tuesday,
when the main trough axis approaches. Even with the driest models,
all of them show some snow during the day, a very fitting pattern
for Christmas Eve. The GFS holds off on the heaviest snow until
overnight Christmas night and into Christmas Day. For now that is
an outlier, as the general model consensus has the snow stopping
overnight.

As mentioned in the marine discussion, on Christmas Day, all eyes
will turn to a strong low tracking northeastward through the Gulf
towards Prince William Sound. The center is decently agreed upon
in the models to track to near Cordova late Wednesday night into
Thursday morning. This would normally be a dud for Anchorage
snow-wise. However, there is good agreement that the supporting
500 mb trough axis remains west of Anchorage, which would support
moisture being drawn northwestward from the low and into Anchorage
and the Mat-Su. Thus, potential for another snowfall event on
Thursday is certainly there. Elsewhere, blizzard conditions are a
significant threat with the low, including for Kodiak, Seward,
Thompson Pass, and potentially Cordova if they can stay cold
enough. All of Southcentral will want to stay particularly attuned
to the forecast over the coming days. One other thing that can be
said for certain is that everywhere away from the immediate coast
will stay plenty cold enough that precipitation type will not be a
problem, snow will be the name of the game.

Model agreement fades quickly on the details beyond the low on
Friday and Saturday, but, it seems likely that an even colder air
mass, colder than the one we have in place presently, will move
into Southcentral, likely causing some areas first sub-zero
temperatures of the winter.

Outside of Anchorage-proper, interesting weather will also be
occurring. For Southwest Alaska, the forecast is actually simple.
The storm track will stay out over the Gulf, with a very
persistent strong upper level trough or low that sits over
Southwest Alaska for much of the long-term period. This means dry,
windy, but most importantly, bitterly cold temperatures. Many
interior areas won't even get to zero for highs, and lows will
routinely flirt with 20 below across the Kuskokwim Valley.
Bitterly cold wind chills will be a significant threat for several
days next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning 187.
 Winter Weather Advisory 161.
MARINE...Hurricane Force Wind Warning 173 175 177 178.
 Storm Warning 155 165 170 172 174 176 179 185.
 Gale Warning 119>121 130 131 138 139 150 160 171 180 181.
 Heavy Freezing Spray 129 140 180 181.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...SB
SOUTHCENTRAL ALASKA...AP
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
MARINE/LONG TERM...JW