Small Craft Advisory 645, NWS Anchorage, AK

892 
FZAK51 PAFC 012348
CWFAER

Coastal Waters Forecast
National Weather Service Anchorage Alaska
348 PM AKDT Fri Sep 1 2017

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.

PKZ197-021230-
348 PM AKDT Fri Sep 1 2017
.SYNOPSIS FOR THE NORTH GULF COAST+KODIAK ISLAND WATERS+
COOK INLET...
A strong front will approach the Gulf from the south Sat night,
then move to the north Gulf coast late Sun. 

$$

PKZ119-021230-
Cape Suckling to Cape Cleare-
348 PM AKDT Fri Sep 1 2017

...SMALL CRAFT ADVISORY SATURDAY NIGHT...

.TONIGHT...SW wind 15 kt. Seas 7 ft.
.SAT...S wind 15 kt. Seas 5 ft.
.SAT NIGHT...SE wind 15 kt increasing to 25 kt after midnight. Seas
5ft building to 8 ft.
.SUN...E wind 45 kt. Seas 13 ft.
.SUN NIGHT...E wind 45 kt. Seas 16 ft.
.MON...SE wind 30 kt. Seas 14 ft.
.TUE...SE wind 20 kt. Seas 12 ft.
.WED...S wind 20 kt. Seas 7 ft.

$$

PKZ120-021230-
Cape Cleare to Gore Point-
348 PM AKDT Fri Sep 1 2017

...SMALL CRAFT ADVISORY SATURDAY NIGHT...

.TONIGHT...SW wind 15 kt. Seas 6 ft.
.SAT...SE wind 20 kt. Seas 5 ft.
.SAT NIGHT...SE wind 20 kt increasing to 30 kt after midnight.
Seas 8 ft.
.SUN...E wind 50 kt. Seas 16 ft.
.SUN NIGHT...E wind 40 kt. Seas 19 ft.
.MON THROUGH TUE...E wind 15 kt. Seas 13 ft.
.WED...S wind 15 kt. Seas 7 ft.

$$

PKZ121-021230-
Resurrection Bay-
348 PM AKDT Fri Sep 1 2017

.TONIGHT...S wind 10 kt becoming N after midnight. Seas 2 ft.
.SAT...S wind 10 kt increasing to 15 kt in the afternoon. Seas 3
ft. Rain.
.SAT NIGHT...Variable wind 10 kt becoming N after midnight. Seas
2 ft. Rain.
.SUN...Variable wind 15 kt. Seas 3 ft.
.SUN NIGHT...N wind 20 kt. Seas 4 ft.
.MON THROUGH TUE...N wind 20 kt. Seas 4 ft.
.WED...N wind 15 kt. Seas 2 ft.

$$

PKZ125-021230-
Prince William Sound-
348 PM AKDT Fri Sep 1 2017

.TONIGHT...SE wind 10 kt. Seas 2 ft.
.SAT...SE wind 10 kt becoming E 15 kt in the afternoon. Seas 2 ft.
.SAT NIGHT...E wind 20 kt. Seas 4 ft. Rain.
.SUN...E wind 30 kt. Seas 6 ft.
.SUN NIGHT...E wind 35 kt. Seas 9 ft.
.MON...E wind 30 kt. Seas 7 ft.
.TUE...E wind 10 kt. Seas 2 ft.
.WED...SE wind 10 kt. Seas 2 ft.

$$

PKZ126-021230-
Port Valdez-
348 PM AKDT Fri Sep 1 2017

.TONIGHT...Variable wind less than 10 kt. Seas 2 ft. Rain showers.
.SAT...Variable wind less than 10 kt. Seas 2 ft.
.SAT NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.SUN...Variable wind less than 10 kt. Seas 2 ft.
.SUN NIGHT...NE wind 10 kt. Seas 2 ft.
.MON THROUGH TUE...E wind 10 kt. Seas 2 ft.
.WED...Variable wind less than 10 kt. Seas 2 ft.

$$

PKZ127-021230-
Valdez Narrows-
348 PM AKDT Fri Sep 1 2017

.TONIGHT...SW wind 10 kt in the evening becoming variable less than 
10 kt. Seas 2 ft. Rain showers.
.SAT...Variable wind less than 10 kt becoming SW 10 kt in the afternoon.
Seas 2 ft.
.SAT NIGHT...N wind 10 kt increasing to 15 kt after midnight. Seas
3 ft.
.SUN AND SUN NIGHT...NE wind 15 kt. Seas 3 ft.
.MON...NE wind 15 kt. Seas 3 ft.
.TUE...NE wind 10 kt. Seas 2 ft.
.WED...Variable wind less than 10 kt. Seas 2 ft.

$$

PKZ128-021230-
Valdez Arm-
348 PM AKDT Fri Sep 1 2017

.TONIGHT...S wind 15 kt becoming NE 10 kt by midnight. Seas 2 ft. 
Rain showers.
.SAT...Variable wind less than 10 kt becoming NE 10 kt in the
afternoon. Seas 2 ft.
.SAT NIGHT...NE wind 10 kt increasing to 15 kt after midnight.
Seas 3 ft.
.SUN...NE wind 10 kt. Seas 2 ft.
.SUN NIGHT...NE wind 15 kt. Seas 3 ft.
.MON THROUGH TUE...NE wind 15 kt. Seas 3 ft.
.WED...NE wind 10 kt. Seas 2 ft.

$$

PKZ129-021230-
Passage Canal-
348 PM AKDT Fri Sep 1 2017

...SMALL CRAFT ADVISORY SATURDAY NIGHT...

.TONIGHT...E wind 15 kt diminishing to 10 kt after midnight. Seas
2 ft. Rain showers.
.SAT...E wind 15 kt. Seas 2 ft. Rain.
.SAT NIGHT...E wind 15 kt increasing to 25 kt after midnight. Seas
2 ft building to 4 ft after midnight. Rain.
.SUN AND SUN NIGHT...E wind 25 kt. Seas 4 ft.
.MON THROUGH WED...E wind 20 kt. Seas 3 ft.

$$

PKZ130-021230-
West of Barren Islands including Kamishak Bay-
348 PM AKDT Fri Sep 1 2017

...GALE WARNING SATURDAY NIGHT...

.TONIGHT...S wind 15 kt. Seas 5 ft.
.SAT...SE wind 25 kt. Seas 7 ft. Rain.
.SAT NIGHT...SE wind 30 kt becoming E 40 kt after midnight. Seas
11 ft. Rain.
.SUN...E wind 50 kt. Seas 15 ft.
.SUN NIGHT...NE wind 45 kt. Seas 14 ft.
.MON...E wind 30 kt. Seas 7 ft.
.TUE...Variable wind 10 kt. Seas 3 ft.
.WED...S wind 15 kt. Seas 4 ft.

$$

PKZ131-021230-
Barren Islands East-
348 PM AKDT Fri Sep 1 2017

...GALE WARNING SATURDAY NIGHT...

.TONIGHT...SW wind 15 kt. Seas 6 ft.
.SAT...SE wind 25 kt. Seas 6 ft.
.SAT NIGHT...SE wind 30 kt increasing to 40 kt after midnight.
Seas 8 ft building to 14 ft after midnight.
.SUN...E wind 50 kt. Seas 18 ft.
.SUN NIGHT...SE wind 45 kt. Seas 21 ft.
.MON...E wind 20 kt. Seas 13 ft.
.TUE...E wind 15 kt. Seas 12 ft.
.WED...S wind 15 kt. Seas 7 ft.

$$

PKZ132-021230-
Marmot Island to Sitkinak-
348 PM AKDT Fri Sep 1 2017

...GALE WARNING SATURDAY NIGHT...

.TONIGHT...SW wind 20 kt. Seas 5 ft.
.SAT...S wind 20 kt becoming SE 30 kt in the afternoon. Seas 8 ft.
.SAT NIGHT...SE wind 40 kt. Seas 16 ft. Rain.
.SUN...E wind 50 kt. Seas 22 ft.
.SUN NIGHT...SE wind 40 kt. Seas 21 ft.
.MON...SE wind 25 kt. Seas 16 ft.
.TUE...SE wind 15 kt. Seas 11 ft.
.WED...S wind 15 kt. Seas 7 ft.

$$

PKZ136-021230-
Chiniak Bay-
348 PM AKDT Fri Sep 1 2017

...SMALL CRAFT ADVISORY SATURDAY NIGHT...

.TONIGHT...S wind 10 kt increasing to 15 kt after midnight. Seas
2 ft.
.SAT...SE wind 20 kt. Seas 2 ft building to 6 ft in the afternoon.
Rain.
.SAT NIGHT...SE wind 30 kt. Seas 11 ft. Rain.
.SUN...E wind 45 kt. Seas 18 ft.
.SUN NIGHT...SE wind 35 kt. Seas 14 ft.
.MON...SE wind 20 kt. Seas 4 ft.
.TUE...E wind 10 kt. Seas 3 ft.
.WED...SW wind 10 kt. Seas 2 ft.

$$

PKZ137-021230-
Marmot Bay-
348 PM AKDT Fri Sep 1 2017

...SMALL CRAFT ADVISORY SATURDAY NIGHT...

.TONIGHT...S wind 10 kt becoming SE 15 kt after midnight. Seas 3 ft.
.SAT...SE wind 20 kt. Seas 4 ft building to 7 ft in the afternoon.
Rain.
.SAT NIGHT...SE wind 30 kt. Seas 12 ft. Rain.
.SUN...E wind 45 kt. Seas 18 ft.
.SUN NIGHT...E wind 35 kt. Seas 16 ft.
.MON...E wind 15 kt. Seas 4 ft.
.TUE...E wind 10 kt. Seas 3 ft.
.WED...SW wind 10 kt. Seas 2 ft.

$$

PKZ138-021230-
Shelikof Strait-
348 PM AKDT Fri Sep 1 2017

...GALE WARNING SATURDAY NIGHT...

.TONIGHT...SW wind 20 kt. Seas 5 ft.
.SAT...NE wind 20 kt. Seas 5 ft. Rain.
.SAT NIGHT...NE wind 30 kt increasing to 40 kt after midnight.
Seas 11 ft. Rain.
.SUN...NE wind 50 kt. Seas 21 ft.
.SUN NIGHT...NE wind 40 kt. Seas 18 ft.
.MON...E wind 25 kt. Seas 7 ft.
.TUE...E wind 15 kt. Seas 3 ft.
.WED...Variable wind 10 kt. Seas 3 ft.

$$

PKZ139-021230-
Cook Inlet Kalgin Island to Point Bede-
348 PM AKDT Fri Sep 1 2017

.TONIGHT...S wind 20 kt. Seas 5 ft.
.SAT...SE wind 20 kt becoming NE 15 kt late afternoon. Seas 5 ft. 
Rain.
.SAT NIGHT...NE wind 20 kt. Seas 5 ft. Rain.
.SUN...NE wind 40 kt. Seas 10 ft.
.SUN NIGHT...NE wind 35 kt. Seas 10 ft.
.MON...NE wind 30 kt. Seas 7 ft.
.TUE...NE wind 10 kt. Seas 3 ft.
.WED...SE wind 10 kt. Seas 3 ft.

$$

PKZ140-021230-
Cook Inlet North of Kalgin Island-
348 PM AKDT Fri Sep 1 2017

.TONIGHT...S wind 20 kt. Seas 5 ft.
.SAT...SE wind 10 kt becoming N in the afternoon. Seas 3 ft.
.SAT NIGHT...NE wind 20 kt. Seas 3 ft building to 5 ft after
midnight.
.SUN AND SUN NIGHT...N wind 30 kt. Seas 8 ft.
.MON...N wind 20 kt. Seas 4 ft.
.TUE...NE wind 10 kt. Seas 3 ft.
.WED...E wind 10 kt. Seas 3 ft.

$$

PKZ141-021230-
Kachemak Bay-
348 PM AKDT Fri Sep 1 2017

...SMALL CRAFT ADVISORY SATURDAY NIGHT...

.TONIGHT...S wind 15 kt. Seas 2 ft.
.SAT...E wind 20 kt. Seas 2 ft. Rain showers.
.SAT NIGHT...E wind 15 kt increasing to 25 kt after midnight. Seas
3 ft. Rain.
.SUN...NE wind 35 kt. Seas 7 ft.
.SUN NIGHT...NE wind 30 kt. Seas 6 ft.
.MON...NE wind 15 kt. Seas 2 ft.
.TUE...NE wind 10 kt. Seas 2 ft.
.WED...SE wind 10 kt. Seas 2 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
807 PM AKDT Thu Aug 31 2017

.ANALYSIS AND UPPER LEVELS...

Two upper level lows dominate the weather across the mainland with
one low just south of the Seward Peninsula, and a second low over
Kodiak Island. While the upper low near the Seward Peninsula is
supporting light scattered showers across the Kuskokwim Delta.
Across Southcentral, there is much more low level support for
widespread showers with the remnants of a front, along with broad
onshore and upslope flow. The afternoon sounding indicates fairly
steep lapse rates and a saturated atmosphere, which is likely
allowing for some spillover precipitation currently and preventing
completely dry conditions in downslope areas. Meanwhile, fairly
dry conditions persist across the Bering with broad northerly
flow. &&

.MODEL DISCUSSION...
The NAM remains the model of choice for both the east and west
domains. The NAM and WRF are particularly doing a good job of
capturing the gap winds through the Alaska Peninsula and
associated mountain wave dynamics. The HRRR is capturing the low
level convergent winds well and is therefore capturing the
rain showers over Anchorage well.

&&

.AVIATION...
PANC...VFR conditions will persist even as light showers continue
to fall into the evening hours. While strengthening down inlet
flow has bent the surface southeasterly Turnagain arm winds away
from PANC with light northwesterly surface winds taking over, wind
shear may still be a concern on the approaches and departures.
Southeast surface winds are likely to push back in to PANC late
afternoon through the evening.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...

Rain showers will continue across the gulf coast and Susitna
Valley through the majority of the overnight hours. In the
meantime, cross barrier flow over the Chugach Mountains will
weaken and allow for scattered showers to develop across Anchorage
and the Matanuska Valley. By Friday morning, a combination of
southeasterly winds out of Turnagain Arm will combine with
southwesterly winds in Cook Inlet (up-Inlet flow) to create a
convergent boundary over west Anchorage. Models are struggling on
where the mesoscale banding will set up as the NAM and GEM show a
negatively tilted upper level axis which would push the banding
west of Fire Island. Regardless, early Friday morning looks wet
with the potential that the morning hours could see steady light
to moderate rainfall.

A rapidly developing low pressure system will develop south of
the Alaska Peninsula Saturday morning and quickly push a gale
force front into the western gulf by Saturday afternoon. This
front is expected to bring moderate to heavy rainfall to Kodiak
Island and the gulf coast through the weekend. However, interior
locations will remain largely on the dry side as impressive cross
barrier flow (35-50 kts) should downslope much of the precipitation
as it interacts with the coastal mountains.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
An upper level low centered over Bristol Bay, which is embedded
within a longwave trough covering most of mainland Alaska, is
bringing widespread cloud cover and rain to Southwest Alaska east
of Bethel. This system will slowly move east bringing a quick
break in the precipitation overnight into tomorrow. Cooler air
filtering down from the north on the backside of this system
combined with partial clearing will allow temperatures to dip
below 40 degrees for most locations tomorrow morning, with low to
mid 30's expected for locations in the Kuskokwim River Valley.
Another upper level low swings down the coast by Friday evening
bringing another round of steady rain for the area starting in
the Y-K Delta Friday night and spreading east and south through
the day on Saturday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

Strong northerly flow over the eastern Bering will begin to taper
off tonight, though wind gusts may still reach gale force coming
out of channeled terrain on the Pacific side of the eastern
Aleutians and southern AKPEN.

A major change in the overall pattern will begin to take shape
tomorrow as a low over Kamchatka will move east into the Bering
Sea by the afternoon. At the same time, a surface low will form to
the south of the Western Aleutians and remnants from former
Typhoon Sanvu will get pulled up into a strong North Pacific jet
stream and ejected northeast towards the island chain. Models are
showing these three systems merging together by Saturday night
into a rapidly intensifying low pressure system about 250 miles
southeast of Cold Bay. A strong 175 kt jet streak will aid in
developing this system into a well developed extra-tropical
cyclone by Sunday, with all models showing the surface pressure
bottoming out at or below 970 mb on Sunday afternoon. Previous
model runs were inconsistent with the low placement and track but
seem to be coming into better agreement, at least through Sunday.
Impacts from this system will be heavy rain along most of the
central and eastern Island chain aided by upslope flow. Winds will
also be very strong but, due to the distance of the low center
from the AKPEN and warm air advecting up from the south, we are
not expecting this to be a storm force low with sustained winds
remaining below 48 kts across a majority of the area. Large swells
are expected though, with long fetch southerly winds leading to
seas above 20 ft for open water locations south of the AKPEN and
southwest of Kodiak.

&&

.LONG TERM FORECAST (Days 3 through 7)...
This forecast period the longwave pattern features broad troughing
with a closed low near St. Lawrence Island and a second closed low
south of the AK Peninsula. As time marches forward, the energy to
the north will be absorbed into the main center of cyclonic
circulation. All of the operational runs ping into a tight
pressure gradient as the low bombs out, widespread diffluence and
moisture advection into southwest and south central AK. There are
some timing issues with the QPF placement and the track of the
surface low, but generally expecting wet and unsettled weather
from this cyclone this forecast period.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...ELN/JA
SOUTHCENTRAL ALASKA...MC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KVP
LONG TERM...PJS