Storm Warning 120, NWS Anchorage, AK

463 
FZAK51 PAFC 260005
CWFAER

Coastal Waters Forecast
National Weather Service Anchorage Alaska
405 PM AKDT Sun Oct 25 2020

Coastal Waters Forecast for the Northern Gulf of Alaska Coast
up to 100 nm out including Kodiak Island and Cook Inlet.

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.

PKZ197-261330-
405 PM AKDT Sun Oct 25 2020
.SYNOPSIS FOR THE NORTH GULF COAST+KODIAK ISLAND WATERS+
COOK INLET...

A 991 mb low 140 nm east of Sand Point moves to 35 nm southwest of
Valdez at 988 mb Mon afternoon and then moves to 50 nm east of
Middleton Island at 1006 mb Tue afternoon.

$$

PKZ119-261330-
Cape Suckling to Cape Cleare-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING THROUGH MONDAY NIGHT...

.TONIGHT...SE wind 40 kt. Seas 15 ft. Rain.
.MON...SW wind 45 kt. Seas 24 ft. Rain.
.MON NIGHT...SW wind 35 kt becoming W 25 kt after midnight. Seas
20 ft.
.TUE...NW wind 20 kt. Seas 14 ft.
.TUE NIGHT...Variable wind 10 kt. Seas 9 ft.
.WED THROUGH THU...N wind 15 kt. Seas 6 ft.
.FRI...N wind 20 kt. Seas 6 ft.

$$

PKZ120-261330-
Cape Cleare to Gore Point-
405 PM AKDT Sun Oct 25 2020

...STORM WARNING MONDAY...

.TONIGHT...E wind 40 kt becoming S 30 kt after midnight. Seas 15
ft. Rain.
.MON...W wind 50 kt diminishing to 40 kt in the afternoon. Seas
20 ft.
.MON NIGHT...W wind 40 kt becoming NW 30 kt after midnight. Seas
19 ft.
.TUE...NW wind 20 kt. Seas 12 ft.
.TUE NIGHT...NW wind 15 kt. Seas 7 ft.
.WED THROUGH THU...N wind 15 kt. Seas 5 ft.
.FRI...N wind 20 kt. Seas 6 ft.

$$

PKZ121-261330-
Resurrection Bay-
405 PM AKDT Sun Oct 25 2020

.TONIGHT...N wind 15 kt. Seas 3 ft. Rain.
.MON...N wind 20 kt. Seas 4 ft.
.MON NIGHT...N wind 20 kt. Seas 4 ft.
.TUE...N wind 20 kt. Seas 4 ft.
.TUE NIGHT...N wind 10 kt. Seas 2 ft.
.WED THROUGH THU...N wind 25 kt. Seas 5 ft.
.FRI...N wind 20 kt. Seas 4 ft.

$$

PKZ125-261330-
Prince William Sound-
405 PM AKDT Sun Oct 25 2020

...SMALL CRAFT ADVISORY THROUGH MONDAY...

.TONIGHT...E wind 30 kt. Seas 6 ft. Rain.
.MON...SW wind 15 kt increasing to 30 kt in the afternoon. Seas
4 ft building to 7 ft in the afternoon.
.MON NIGHT...N wind 20 kt. Seas 3 ft.
.TUE...N wind 15 kt. Seas 2 ft.
.TUE NIGHT...N wind 10 kt. Seas 2 ft.
.WED THROUGH THU...N wind 10 kt. Seas 2 ft.
.FRI...N wind 15 kt. Seas 3 ft.

$$

PKZ126-261330-
Port Valdez-
405 PM AKDT Sun Oct 25 2020

.TONIGHT...NE wind 10 kt. Seas 2 ft. Rain and snow.
.MON...E wind 10 kt in the morning becoming variable less than
10 kt. Seas 2 ft. Rain.
.MON NIGHT...E wind 10 kt. Seas 2 ft.
.TUE...NE wind 10 kt. Seas 2 ft.
.TUE NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.WED THROUGH THU...NE wind 15 kt. Seas 3 ft.
.FRI...NE wind 10 kt. Seas 2 ft.

$$

PKZ127-261330-
Valdez Narrows-
405 PM AKDT Sun Oct 25 2020

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...NE wind 25 kt. Seas 3 ft. Rain.
.MON...NE wind 20 kt becoming SW 15 kt in the afternoon. Seas 3
ft. Rain.
.MON NIGHT...NE wind 20 kt. Seas 3 ft.
.TUE AND TUE NIGHT...NE wind 25 kt. Seas 3 ft.
.WED THROUGH THU...NE wind 30 kt. Seas 3 ft.
.FRI...NE wind 15 kt. Seas 3 ft.

$$

PKZ128-261330-
Valdez Arm-
405 PM AKDT Sun Oct 25 2020

.TONIGHT...NE wind 20 kt. Seas 4 ft. Rain.
.MON...NE wind 15 kt becoming SW wind 10 kt in the afternoon. Seas
3 ft. Rain.
.MON NIGHT...NE wind 15 kt. Seas 3 ft.
.TUE AND TUE NIGHT...NE wind 20 kt. Seas 4 ft.
.WED THROUGH THU...NE wind 25 kt. Seas 5 ft.
.FRI...NE wind 15 kt. Seas 3 ft.

$$

PKZ129-261330-
Passage Canal-
405 PM AKDT Sun Oct 25 2020

...SMALL CRAFT ADVISORY MONDAY NIGHT...

.TONIGHT...E wind 15 kt. Seas 2 ft. Rain and snow.
.MON...W wind 20 kt. Gusts to 30 kt near Whittier. Seas 2 ft.
.MON NIGHT...W wind 25 kt. Gusts to 35 kt near Whittier. Seas 3 ft.
.TUE...W wind 20 kt. Seas 2 ft.
.TUE NIGHT...W wind 10 kt. Seas 2 ft.
.WED THROUGH THU...W wind 25 kt. Seas 2 ft.
.FRI...W wind 10 kt. Seas 2 ft.

$$

PKZ130-261330-
West of Barren Islands including Kamishak Bay-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING THROUGH MONDAY NIGHT...

.TONIGHT...NE wind 40 kt with gusts to 50 kt becoming NW 30 kt after
midnight. Seas 16 ft. Rain.
.MON...W wind 35 kt increasing to 45 kt in the afternoon. Seas
16 ft.
.MON NIGHT...W wind 45 kt diminishing to 35 kt after midnight.
Seas 15 ft subsiding to 10 ft after midnight.
.TUE...NW wind 30 kt. Seas 8 ft.
.TUE NIGHT...NW wind 25 kt. Seas 5 ft.
.WED THROUGH THU...NW wind 20 kt. Seas 5 ft.
.FRI...NW wind 30 kt. Seas 8 ft.

$$

PKZ131-261330-
Barren Islands East-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING THROUGH MONDAY NIGHT...

.TONIGHT...SE wind 45 kt with gusts to 60 kt becoming SW 40 kt after
midnight. Seas 16 ft. Rain.
.MON...W wind 40 kt. Seas 18 ft.
.MON NIGHT...W wind 40 kt. Seas 17 ft.
.TUE...NW wind 30 kt. Seas 12 ft.
.TUE NIGHT...NW wind 25 kt. Seas 8 ft.
.WED THROUGH THU...NW wind 20 kt. Seas 6 ft.
.FRI...NW wind 30 kt. Seas 8 ft.

$$

PKZ132-261330-
Marmot Island to Sitkinak-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING THROUGH MONDAY NIGHT...

.TONIGHT...S wind 30 kt becoming W 45 kt after midnight. Seas 14
ft building to 20 ft after midnight. Rain.
.MON...W wind 40 kt. Seas 19 ft.
.MON NIGHT...W wind 35 kt. Seas 15 ft.
.TUE...W wind 25 kt. Seas 11 ft.
.TUE NIGHT...W wind 20 kt. Seas 7 ft.
.WED...NW wind 15 kt. Seas 6 ft.
.THU...N wind 20 kt. Seas 5 ft.
.FRI...NW wind 30 kt. Seas 9 ft.

$$

PKZ136-261330-
Chiniak Bay-
405 PM AKDT Sun Oct 25 2020

...SMALL CRAFT ADVISORY MONDAY AND MONDAY NIGHT...

.TONIGHT...SW wind 20 kt. Seas 3 ft. Rain.
.MON...W wind 30 kt. Seas 5 ft.
.MON NIGHT...W wind 30 kt diminishing to 20 kt after midnight.
Seas 5 ft subsiding to 3 ft after midnight.
.TUE...W wind 20 kt. Seas 3 ft.
.TUE NIGHT...NW wind 15 kt. Seas 2 ft.
.WED...NW wind 10 kt. Seas 1 ft.
.THU...NW wind 15 kt. Seas 2 ft.
.FRI...NW wind 20 kt. Seas 3 ft.

$$

PKZ137-261330-
Marmot Bay-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING MONDAY...

.TONIGHT...E wind 15 kt becoming W 25 kt after midnight. Seas 4
ft. Rain.
.MON...W wind 35 kt. Seas 8 ft.
.MON NIGHT...W wind 30 kt. Seas 7 ft.
.TUE...W wind 20 kt. Seas 4 ft.
.TUE NIGHT...W wind 15 kt. Seas 2 ft.
.WED...NW wind 10 kt. Seas 1 ft.
.THU...NW wind 15 kt. Seas 2 ft.
.FRI...NW wind 25 kt. Seas 4 ft.

$$

PKZ138-261330-
Shelikof Strait-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...NE wind 40 kt becoming W 30 kt after midnight. Seas 16
ft subsiding to 10 ft after midnight. Rain.
.MON...W wind 35 kt. Seas 12 ft.
.MON NIGHT...W wind 30 kt. Seas 9 ft.
.TUE AND TUE NIGHT...W wind 20 kt. Seas 5 ft.
.WED...NW wind 15 kt. Seas 3 ft.
.THU...N wind 20 kt. Seas 4 ft.
.FRI...NW wind 25 kt. Seas 6 ft.

$$

PKZ139-261330-
Cook Inlet Kalgin Island to Point Bede-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING THROUGH MONDAY...

.TONIGHT...NE wind 35 kt. Seas 14 ft. Rain.
.MON...SW wind 35 kt. Seas 11 ft.
.MON NIGHT...NW wind 25 kt diminishing to 15 kt after midnight.
Seas 6 ft subsiding to 3 ft after midnight.
.TUE AND TUE NIGHT...N wind 10 kt. Seas 3 ft.
.WED THROUGH THU...N wind 15 kt. Seas 3 ft.
.FRI...N wind 20 kt. Seas 4 ft.

$$

PKZ140-261330-
Cook Inlet North of Kalgin Island-
405 PM AKDT Sun Oct 25 2020

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...NE wind 30 kt. Seas 10 ft. Rain and snow.
.MON...SW wind 15 kt becoming N 10 kt in the afternoon. Seas 3 ft.
.MON NIGHT...N wind 10 kt in the evening becoming variable less
than 10 kt. Seas 2 ft.
.TUE AND TUE NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.WED...N wind 15 kt. Seas 3 ft.
.THU...N wind 10 kt. Seas 3 ft.
.FRI...N wind 15 kt. Seas 4 ft.

$$

PKZ141-261330-
Kachemak Bay-
405 PM AKDT Sun Oct 25 2020

...GALE WARNING MONDAY...

.TONIGHT...N wind 20 kt. Seas 3 ft. Rain.
.MON...W wind 35 kt. Seas 13 ft.
.MON NIGHT...NW wind 25 kt becoming N 10 kt after midnight. Seas
6 ft subsiding to 2 ft after midnight.
.TUE AND TUE NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.WED THROUGH THU...N wind 10 kt. Seas 2 ft.
.FRI...N wind 15 kt. Seas 2 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
642 PM AKDT Sat Oct 24 2020

.ANALYSIS AND UPPER LEVELS...
A broad upper level trough centered over the Eastern Bering is
brought widespread rain to areas of Southwest Alaska, as well as
much of the Gulf Coast this morning. Returns from Kenai radar for
much of the day also indicated widespread precipitation, however
very dry low levels and downsloping prevented the vast majority of
that precipitation from reaching the ground. Instead much of
Southcentral saw a generally cloudy but dry day, but with a few
passing flurries. Well south of the area near 35N in the Central
Pacific, a developing wave is present under a 130 kt jet streak.
This is expected to continue developing over the next 24 hours as
it quickly moves northward into the Gulf where it will be the
primary weather system of focus late Sunday-Monday. Over the
Central-Western Bering the weather is much quieter under broad
northerly flow and cold air advection, which is indicated by the
extensive shower activity and lack of fog or stratus.

&&

.MODEL DISCUSSION...
The lack of model agreement in the first 48 hours, especially on
the synoptic scale, continues to be a major forecast challenge
with the track/intensity of the approaching Gulf low for Sunday.
One area that the models continue to diverge significantly on is
when comparing the Gulf low track from the global GFS/EC and
mesoscale NAM starting Sunday afternoon. Overnight the NAM and GFS
continued to show wildly different solutions, while the EC was a
reasonable compromise between the two. Since 12z this morning
however the global GFS and EC have come much more in line with a
deeper low track skirting the Kodiak Island and Western Prince
William Sound coasts, while the NAM remains much weaker and
further east. Since the development of this system is still well
south of the area near the edge of the NAM domain, the current
forecast favors the global models which typically have stronger
performance in these types of situations. However to keep from
making major changes the forecast was only trended in their
direction. As a result forecast confidence generally remains low,
especially with precip type and any snow accumulations from Palmer
westward for Monday.

&&

.AVIATION...
PANC...LLWS will continue to occur over the terminal today before
beginning to diminish after 2z this evening. There is some
question as to exactly how quickly this will occur, but there is
good confidence in a general weakening trend between 0-3z.
Afterwards conditions should remain VFR with light north winds
until ceilings begin to fall below 5000 ft with a rain/snow mix
around 18z Sun. Afterwards there is a potential for accumulating
snow and IFR conditions late Sun-Mon, however that is still being
monitored as confidence is low.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2/Saturday
afternoon through Monday afternoon)...

A front over the central Gulf continues to gradually lift
northward bringing gale force winds to the northern Gulf waters
this evening. Precipitation is spreading inland with this front
and will continue to do so this evening with the greatest
precipitation expected to fall along the northern Gulf Coast. One
caveat continues to be the amount of dry air in place at lower
levels, so the onset of precipitation will likely be delayed,
especially for the western Kenai Peninsula and Anchorage Bowl.
Rain is expected along the coast while interior locations will see
snow.

For Sunday, the focus quickly shifts to the interaction between an
upper level trough over the eastern Bering and an inbound,
moisture-laden low from the North Pacific. Models have struggled
with these features over the past few days, however there is now
much higher confidence in this storm taking a more westerly track
and moving over the eastern Kenai Peninsula/western Prince William
Sound area (a GFS/EC solution). Additionally, one other challenge
has been the possibility for downsloping (leading to a reduction
in QPF values) however this is looking less likely. As a result,
this forecast package includes generally higher QPF values with
this next system for Sunday night into Monday.

The final challenge is precipitation type. For the Anchorage Bowl
and Mat-Su Valleys, current thinking is that precipitation will
start as rain with a transition to snow Sunday night. Accumulation
amounts still remain somewhat uncertain, but it is looking increasingly
likely that the greatest snowfall will be along the Anchorage
Hillside. As this system lifts inland and moves eastward,
widespread snow is expected over the Copper River Basin. Winter
Weather Advisories have been issued for Thompson Pass and the
Copper River Basin Sunday into Monday.

This forecast continues to evolve - please stay tuned as the
details begin to fall into place over the next 24 hours.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3:
Tonight through Tuesday)...

Widespread showers will continue to move north and across
Southwest Alaska tonight. Rainfall observations from this
afternoon implied steady rain passing through Bristol Bay
including New Stuyahok and Manokotak, the Lower Kuskokwim Valley
and portions of Kuskokwim Delta. The arrival of a weakening low
over the central Bering will force more rain over the region
through at least Monday. As for the snow, much of it will fall
over the lower Kuskokwim Valley and near the Kuskokwim Delta
starting Sunday night. Colder temperatures aloft associated with
the weakening low from the Bering will cross the Kuskokwim Delta
Sunday night, which will increase the potential for snow showers
early in the week.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Tonight through Tuesday)...

The upper low has passed east of Pribilof Islands, and it's
slowly making its way through eastern Bering tonight and Sunday.
Small craft conditions were continued for another day for several
marine zones until winds and seas subside Sunday night. The
leading edge of a Northwest Pacific front will approach the
western Bering as early as Sunday morning. This could be a weak
frontal system, but will continue to monitor the situation
closely. As a result, it will be relatively quiet over the next
few days.

&&

.MARINE (Days 3 through 5: Tuesday through Thursday)...

The weather to watch on Tuesday will be an area of low pressure
located south of Prince William Sound. Uncertainty remains with
the strength and track of this system, however, models agree on
gale force winds across the central Gulf before the low moves
inland on Wednesday. Through Wednesday, calmer conditions will
provide for light winds across much of the Gulf. Over the Bering
Sea and Aleutians, winds and waves look to remain relatively calm
for the forecast period. There is potential for an area of low
pressure to skirt the chain beginning Wednesday afternoon,
however, model confidence is low at this time.

&&

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

A weak surface low lingers over the Northern Gulf on Tuesday and
tracks slowly to the east. Meanwhile, an upper-level ridge sets up
over the interior, beginning the flow of cold air towards
Southern Alaska, which will be quickly pushed out by a series of
arctic troughs moving across the state mid-week. While the
greatest impacts will remain well to the north, temperatures for
the Southwest and Southcentral regions will drop as the colder air
is advected in.

Late next week, there is better agreement between the Canadian and
ECMWF models across all parameters for a North Pacific surface
low that will pass just south of the Aleutians. The GFS seems too
slow and is quite a bit deeper in comparison, so less reliability
is placed on this solution. This system can potentially bring
strong winds to the coastal waters.

By Saturday, another system approaches the Aleutians from the
west. There is decent model agreement with this surface low. The
ECMWF seems fast and travels with an easterly path but
approximates a similar depth to the Canadian. The GFS, while much
deeper than the other two, shares a similar location and path
(southeasterly) with the Canadian.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory: 131, 141.
MARINE...Gale Warning: 119, 351.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...DEK
SOUTHCENTRAL ALASKA...KO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
MARINE/LONG TERM...CK/KM