Small Craft Advisory 139, NWS Anchorage, AK

Issued

Feb 15, 2021, 3:23 PM AKST (00:23 UTC)

Expired

Feb 16, 2021, 4:00 AM AKST

In force

13 hr

Issued by

NWS Anchorage, AK

725 
FZAK51 PAFC 160023
CWFAER

Coastal Waters Forecast
National Weather Service Anchorage Alaska
323 PM AKST Mon Feb 15 2021

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.

PKZ197-161300-
323 PM AKST Mon Feb 15 2021
.SYNOPSIS FOR THE NORTH GULF COAST+KODIAK ISLAND WATERS+
COOK INLET...

A front over the Central Gulf moves to the Northern Gulf Mon night, 
then dissipates Tue. A second front enters the Western Gulf Tue 
afternoon, then moves to the North Gulf Coast by Wed morning.

$$

PKZ119-161300-
Cape Suckling to Cape Cleare-
323 PM AKST Mon Feb 15 2021

...SMALL CRAFT ADVISORY THROUGH TUESDAY NIGHT...

.TONIGHT...Variable wind 15 kt. Seas 9 ft. Rain and snow showers.
.TUE...SW wind 15 kt. Seas 8 ft. Snow.
.TUE NIGHT...SE wind 15 kt increasing to 30 kt after midnight.
Seas 8 ft. Rain and snow.
.WED...SE wind 35 kt. Seas 11 ft.
.WED NIGHT...SE wind 30 kt. Seas 12 ft.
.THU...NE wind 25 kt. Seas 14 ft.
.FRI...SW wind 30 kt. Seas 14 ft.
.SAT...Variable wind 10 kt. Seas 9 ft.

$$

PKZ120-161300-
Cape Cleare to Gore Point-
323 PM AKST Mon Feb 15 2021

...SMALL CRAFT ADVISORY TONIGHT AND TUESDAY NIGHT...

.TONIGHT...Variable wind 15 kt. Seas 8 ft. Rain and snow showers.
.TUE...Variable wind 10 kt. Seas 7 ft.
.TUE NIGHT...SE wind 20 kt increasing to 30 kt after midnight.
Seas 8 ft. Rain and snow.
.WED...SE wind 15 kt. Seas 9 ft.
.WED NIGHT...NE wind 25 kt. Seas 8 ft.
.THU...NW wind 30 kt. Seas 15 ft.
.FRI...W wind 35 kt. Seas 14 ft.
.SAT...W wind 15 kt. Seas 9 ft.

$$

PKZ121-161300-
Resurrection Bay-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind less than 10 kt. Seas 2 ft. Snow.
.TUE...Variable wind less than 10 kt. Seas 2 ft.
.TUE NIGHT...Variable wind less than 10 kt becoming S 10 kt after
midnight. Seas 2 ft. Snow.
.WED...S wind 10 kt. Seas 2 ft.
.WED NIGHT...N wind 10 kt. Seas 2 ft.
.THU THROUGH FRI...N wind 20 kt. Seas 4 ft.
.SAT...N wind 10 kt. Seas 2 ft.

$$

PKZ125-161300-
Prince William Sound-
323 PM AKST Mon Feb 15 2021

...SMALL CRAFT ADVISORY TUESDAY NIGHT...

.TONIGHT...NE wind 10 kt. Seas 2 ft. Snow.
.TUE...NE wind 10 kt in the morning becoming variable less than
10 kt. Seas 2 ft.
.TUE NIGHT...E wind 15 kt increasing to 25 kt after midnight. Seas
3 ft building to 6 ft after midnight. Snow showers and rain.
.WED...E wind 35 kt. Seas 7 ft.
.WED NIGHT...E wind 30 kt. Seas 6 ft.
.THU...NE wind 20 kt. Seas 4 ft.
.FRI...SW wind 15 kt. Seas 2 ft.
.SAT...N wind 10 kt. Seas 2 ft.

$$

PKZ126-161300-
Port Valdez-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind less than 10 kt. Seas 2 ft. Snow.
.TUE...Variable wind less than 10 kt. Seas 2 ft. Snow.
.TUE NIGHT...Variable wind less than 10 kt. Seas 2 ft. Snow.
.WED AND WED NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.THU...E wind 10 kt. Seas 2 ft.
.FRI...NE wind 15 kt. Seas 2 ft.
.SAT...Variable wind less than 10 kt. Seas 2 ft.

$$

PKZ127-161300-
Valdez Narrows-
323 PM AKST Mon Feb 15 2021

.TONIGHT...NE wind 15 kt. Seas 3 ft. Freezing spray. Snow.
.TUE...NE wind 10 kt in the morning becoming variable less than
10 kt. Seas 2 ft. Snow.
.TUE NIGHT...Variable wind less than 10 kt. Seas 2 ft. Snow.
.WED AND WED NIGHT...NE wind 10 kt. Seas 2 ft.
.THU THROUGH FRI...NE wind 20 kt. Seas 3 ft.
.SAT...NE wind 10 kt. Seas 2 ft.

$$

PKZ128-161300-
Valdez Arm-
323 PM AKST Mon Feb 15 2021

.TONIGHT...NE wind 10 kt. Seas 2 ft. Snow.
.TUE...Variable wind less than 10 kt. Seas 2 ft. Snow.
.TUE NIGHT...Variable wind less than 10 kt. Seas 2 ft. Snow.
.WED AND WED NIGHT...NE wind 10 kt. Seas 2 ft.
.THU THROUGH FRI...NE wind 15 kt. Seas 3 ft.
.SAT...NE wind 10 kt. Seas 2 ft.

$$

PKZ129-161300-
Passage Canal-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind less than 10 kt. Seas 2 ft. Snow.
.TUE...Variable wind less than 10 kt. Seas 2 ft. Snow.
.TUE NIGHT...E wind 10 kt increasing to 15 kt after midnight. Seas
2 ft. Snow.
.WED AND WED NIGHT...E wind 20 kt. Seas 3 ft.
.THU...E wind 10 kt. Seas 2 ft.
.FRI...W wind 10 kt. Seas 2 ft.
.SAT...Variable wind 10 kt. Seas 2 ft.

$$

PKZ130-161300-
West of Barren Islands including Kamishak Bay-
323 PM AKST Mon Feb 15 2021

...SMALL CRAFT ADVISORY TUESDAY NIGHT...

.TONIGHT...NE wind 15 kt. Seas 3 ft.
.TUE...Variable wind 10 kt becoming E 15 kt in the afternoon. 
Seas 3 ft.
.TUE NIGHT...E wind 30 kt. Seas 8 ft. Rain and snow.
.WED...NE wind 30 kt. Seas 7 ft.
.WED NIGHT...NE wind 20 kt. Seas 5 ft.
.THU THROUGH FRI...W wind 35 kt. Seas 10 ft.
.SAT...NW wind 20 kt. Seas 5 ft.

$$

PKZ131-161300-
Barren Islands East-
323 PM AKST Mon Feb 15 2021

...SMALL CRAFT ADVISORY THROUGH TUESDAY NIGHT...

.TONIGHT...SW wind 15 kt. Seas 8 ft.
.TUE...S wind 15 kt. Seas 8 ft.
.TUE NIGHT...SE wind 25 kt. Seas 8 ft. Rain.
.WED...SW wind 15 kt. Seas 9 ft.
.WED NIGHT...Variable wind 10 kt. Seas 7 ft.
.THU THROUGH FRI...W wind 35 kt. Seas 14 ft.
.SAT...NW wind 20 kt. Seas 10 ft.

$$

PKZ132-161300-
Marmot Island to Sitkinak-
323 PM AKST Mon Feb 15 2021

...SMALL CRAFT ADVISORY THROUGH TUESDAY NIGHT...

.TONIGHT...SW wind 20 kt. Seas 10 ft.
.TUE...SW wind 15 kt becoming SE 25 kt in the afternoon. Seas 10
ft. Rain.
.TUE NIGHT...SE wind 25 kt becoming SW 15 kt after midnight. Seas 10
ft.
.WED...S wind 15 kt. Seas 9 ft.
.WED NIGHT...Variable wind 10 kt. Seas 7 ft.
.THU THROUGH FRI...W wind 30 kt. Seas 14 ft.
.SAT...NW wind 25 kt. Seas 11 ft.

$$

PKZ136-161300-
Chiniak Bay-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind less than 10 kt. Seas 2 ft.
.TUE...SW wind 10 kt becoming S 15 kt in the afternoon. Seas 2 ft.
Rain.
.TUE NIGHT...SE wind 20 kt becoming SW 10 kt after midnight. Seas
5 ft subsiding to 2 ft after midnight.
.WED...S wind 10 kt. Seas 1 ft.
.WED NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.THU THROUGH FRI...W wind 25 kt. Seas 4 ft.
.SAT...NW wind 10 kt. Seas 1 ft.

$$

PKZ137-161300-
Marmot Bay-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind less than 10 kt. Seas 2 ft.
.TUE...Variable wind less than 10 kt becoming SE 15 kt in the
afternoon. Seas 3 ft. Rain.
.TUE NIGHT...SE wind 20 kt becoming variable less 10 kt after 
midnight. Seas 7 ft subsiding to 3 ft after midnight. Rain.
.WED...Variable wind less than 10 kt. Seas 3 ft.
.WED NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.THU THROUGH FRI...W wind 25 kt. Seas 6 ft.
.SAT...NW wind 15 kt. Seas 2 ft.

$$

PKZ138-161300-
Shelikof Strait-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind 10 kt. Seas 2 ft.
.TUE...Variable wind 10 kt becoming E 15 kt in the afternoon. 
Seas 3 ft.
.TUE NIGHT...E wind 20 kt becoming variable 15 kt after midnight. 
Seas 5 ft subsiding to 3 ft after midnight. Rain.
.WED...E wind 15 kt. Seas 3 ft.
.WED NIGHT...Variable wind 10 kt. Seas 2 ft.
.THU THROUGH FRI...W wind 25 kt. Seas 6 ft.
.SAT...NW wind 15 kt. Seas 4 ft.

$$

PKZ139-161300-
Cook Inlet Kalgin Island to Point Bede-
323 PM AKST Mon Feb 15 2021

...SMALL CRAFT ADVISORY TUESDAY NIGHT...

.TONIGHT...NE wind 20 kt diminishing to 10 kt after midnight. Seas 5
ft subsiding to 3 ft after midnight. Freezing spray.
.TUE...NE wind 10 kt increasing to 15 kt in the afternoon. 
Seas 3 ft.
.TUE NIGHT...NE wind 20 kt increasing to 30 kt after midnight. Seas 
5 ft building to 8 ft after midnight. Freezing spray. Rain and snow.
.WED...NE wind 30 kt. Seas 6 ft.
.WED NIGHT...N wind 20 kt. Seas 5 ft.
.THU...NW wind 20 kt. Seas 5 ft.
.FRI...NW wind 25 kt. Seas 5 ft.
.SAT...N wind 15 kt. Seas 3 ft.

$$

PKZ140-161300-
Cook Inlet North of Kalgin Island-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind less than 10 kt.
.TUE...Variable wind less than 10 kt becoming NE 10 kt in the
afternoon.
.TUE NIGHT...N wind 15 kt.
.WED...NE wind 15 kt.
.WED NIGHT...N wind 10 kt.
.THU THROUGH SAT...N wind 10 kt.

$$

PKZ141-161300-
Kachemak Bay-
323 PM AKST Mon Feb 15 2021

.TONIGHT...Variable wind less than 10 kt. Seas 2 ft. Rain showers.
.TUE...Variable wind less than 10 kt. Seas 2 ft.
.TUE NIGHT...NE wind 10 kt. Seas 2 ft. Rain and snow.
.WED AND WED NIGHT...NE wind 10 kt. Seas 2 ft.
.THU THROUGH FRI...NW wind 20 kt. Seas 5 ft.
.SAT...NW wind 10 kt. Seas 2 ft.

$$

NWS Anchorage, AK wrote its last area forecast discussion before this small craft advisory went out at Feb 15, 4:17 AM AKST, 11 hours 6 minutes earlier.

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
417 AM AKST Mon Feb 15 2021

.ANALYSIS AND UPPER LEVELS...

A broad, vertically stacked low continues to spin in place over
the central Bering with the low center positioned just east of
Adak. A frontal boundary associated with this low is visible on
satellite imagery and extends along the Southwest coast, over the
Alaska Peninsula, and into the western Gulf. Meanwhile an upper
level ridge over the Alaska-Yukon border has kept conditions clear
and dry over the Copper River Basin and eastern Southcentral.
Farther west, higher clouds have begun to develop over the Susitna
Valley and are gradually spreading toward the southeast and
filling in over Southcentral this morning.

&&

.MODEL DISCUSSION...

Model solutions remain in great synoptic agreement through the
short term. The main forecast challenge continues to be
precipitation amounts across Southcentral as the front extending
across the Gulf lifts inland through Tuesday. Model solutions are
also struggling to resolve the next low arriving over Southcentral
Tuesday into Wednesday. While there is good agreement with an
upper level trough over the Alaska Peninsula progressing eastward
Wednesday morning, at the surface, models disagree on the strength
of a surface low forming in the vicinity of Kodiak Island and the
timing in which the associated front moves inland over
Southcentral.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. A front
lifting inland tonight will reduce conditions to MVFR during the
overnight hours into Tuesday morning with light snow expected.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today
through Wednesday Night)...

A frontal boundary draped over the northern half of Kodiak Island
this morning will slowly lift northward today as an upper-level
shortwave moves from the western Gulf to the northern Gulf. A
steady, light rain this morning over portions of Kodiak Island
will transition to scattered showers as the front and upper-level
wave move north. Farther north, light snow will develop across the
southern Kenai Peninsula later this morning and spread into Prince
William Sound, the Anchorage Bowl, and Mat-Su Valleys tonight.
Light snow showers will persist through Tuesday as the surface
front stalls and weakens along the coast and a series of upper-
level shortwaves lift north across the region. A general 1 to 3
inches is still expected with this system; however, a persistent
moist, southwesterly flow and colder air working in aloft may
favor localized higher amounts in upslope areas such as the
Anchorage Hillside and along the Parks Highway from Willow to
Talkeetna. Snowfall amounts of 6 to 8 inches are not out of the
question for Hatcher Pass, given the favored southwesterly flow.

This system will gradually weaken by late Tuesday as a second,
more potent storm system moves into the western Gulf. A developing
surface low near the Barren Islands and associated front sweeping
into the northern Gulf looks to bring widespread snow to the Kenai
and Chugach Mountains beginning early Wednesday morning.
Precipitation will also likely start as snow for coastal locations
along the eastern Kenai Peninsula and Prince William Sound. There
is still some uncertainty as to how strong and how far north the
front will track. The strength and position of the front will have
influence on whether enough warm air works in and changes snow to
rain along the coast and whether there is a significant increase
in freezing levels to vary snow amounts in the higher elevations.
Gap winds will also increase ahead of the front which may cause
concern for blowing snow in Portage Valley and Turnagain Pass, at
least initially before temperatures increase. As for locations in
the lee of the Kenai and Chugach Mountains, a strong cross-
barrier flow should act to limit precipitation totals due to
downsloping conditions.

&&

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

Broad low pressure exists across much of the Southwest as a
multitude of shortwaves move across the Mainland. As a result,
much of the region will remain under widespread showers over the
next couple of days. Temperatures will be at or above freezing for
Bristol Bay and the AKPEN, and below freezing elsewhere.
Regardless, precipitation will be mostly snow across the
Southwest, will accumulations of 1-2 inches in the lower
elevations and up to 6 inches for the higher elevations. By
Wednesday, the Bering low begins weakening at a faster rate and
moves off to the east. After the low passes and dissipates, the
Southwest should see a some dry and cloudy conditions as well as
some cooler temperatures as flow transitions to northerly by late
Wednesday into Thursday.

&&

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

Broad low pressure extends across the Bering and Southwest through
mid-week as a vertically stacked low remains almost stationary
between Adak and Unalaska through Tuesday night. This systems
loses much of its jet support by late tonight and begins rapidly
weakening by Tuesday afternoon allowing its energy to be absorbed
by a secondary North Pacific low approaching the Gulf late
Wednesday. Thus, the low moves off to the east Wednesday, pulling
colder northerly air behind it and spilling into the Eastern
Aleutians and Southern AKPEN. With this, precipitation will
transition from a rain/rain-snow mix back to mostly snow for these
areas starting Wednesday night. There will be a quick break
Wednesday evening through early Thursday morning until a front
off a Kamchatka low pushes into the Western Bering. This will
bring a round of gale force winds and precipitation to the Western
Aleutians starting early Thursday morning.

&&

.MARINE (Days 3 through 5: Wednesday through Friday)...

Bering Sea: A low exits Bristol Bay for Thu. Model changes are
similar, so confidence is good. Widespread small craft winds and
waves over the central and eastern Bering diminish Thu. Wave
heights to 8 feet expected south of the ice edge. A well
developed low and front enters the Western Aleutians and Bering
and moves to the Central Aleutians and Bering by Fri. Widespread
high end gale force winds along the front through Fri. Wave
heights to 20 feet possible in the Bering, 14 feet on the Pacific
side of the Aleutians.

Gulf of Alaska: A front across the Gulf moves to the north Gulf
Coast for Fri. Model changes are similar, so confidence is good.
Widespread small craft winds and waves with areas of gale force
winds with the front will diminish late Thu, but gales will linger
away from the front over the Barren Islands, Cook Inlet and
Shelikof Strait. Wave heights with the front up to 20 feet
possible through Fri.

&&

.LONG TERM FORECAST (Days 3 through 7: Wednesday through Sunday)...

A low over the eastern Bering will be the primary weather maker
across Southern Alaska to start off the long-term forecast on
Wednesday. The leading front and upper level wave will move north
out of the North Pacific and impact the north Gulf Coast. A round
of potentially heavy snow is expected along the Kenai Peninsula
and Seward Highway through the day. Already by Thursday, model
discrepancies emerge, namely how long the heaviest precipitation
persists along the coast. Some of the models try to bring some of
the moisture into the Cook Inlet region, but that too is
uncertain. Across Southwest Alaska, precipitation early on in the
day will spread northward, resulting in decreasing precipitation
rates by Wednesday night, though some light precipitation will
still be around. A front will move into the Western Aleutians
Thursday morning. The front will spread across all of the Bering
by Friday afternoon. Weak embedded lows may form along the front,
but will not significantly impact the placement of the front.

For Southcentral, the discrepancies on a late-week round of snow
are large enough that very little detail can be determined at this
point. Most of the guidance suggests snow will move in at some
point, but whether that occurs Thursday or Friday in association
with a Gulf low or if it will be entirely driven by upslope
southwesterly flow and upper level support is highly uncertain.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale: 175, 176, 177, 185, 412.
         Heavy Freezing Spray: 185
         Marine Weather Statement: 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KO
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KM
MARINE/LONG TERM...MK/JW

Small Craft Advisories in Alaska, 2021Every small craft advisory in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text.