Small Craft Advisory 821, NWS Anchorage, AK

Issued

Sep 21, 2023, 2:41 PM AKDT (22:41 UTC)

Expired

Sep 22, 2023, 3:30 AM AKDT

In force

13 hr

Issued by

NWS Anchorage, AK

664 
FZAK52 PAFC 212241
CWFALU

Coastal Waters Forecast
National Weather Service Anchorage Alaska
241 PM AKDT Thu Sep 21 2023

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.

PKZ199-221130-
241 PM AKDT Thu Sep 21 2023
.SYNOPSIS FOR SOUTHWEST ALASKA+BRISTOL BAY+THE ALASKA
PENINSULA WATERS AND THE ALEUTIAN ISLANDS...

A 979 mb low 380 nm North of Attu moves to 40 nm North of St 
Matthew Island at 995 mb for Sat afternoon. Its strong front moves
into Western Alaska and across the Alaska Peninsula by Sat 
afternoon. A 1002 mb Sea of Okhotsk low and front moves into the 
Western Bering through Sat afternoon.

$$

PKZ750-221130-
Sitkinak to Castle Cape out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...NW wind 25 kt diminishing to 15 kt after midnight. Seas
6 ft.
.FRI...W wind 15 kt. Seas 3 ft.
.FRI NIGHT...Variable wind 10 kt. Seas 2 ft.
.SAT AND SAT NIGHT...Variable wind 10 kt. Seas 4 ft.
.SUN...Variable wind 10 kt. Seas 2 ft.
.MON...NW wind 15 kt. Seas 3 ft.
.TUE...NW wind 20 kt. Seas 4 ft.

$$

PKZ751-221130-
Sitkinak to Castle Cape from 15 to 100 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...NW wind 25 kt becoming W 15 kt after midnight. Seas 9
ft.
.FRI...Variable wind 10 kt. Seas 5 ft.
.FRI NIGHT...Variable wind 10 kt. Seas 4 ft.
.SAT...Variable wind 10 kt. Seas 4 ft.
.SAT NIGHT...NW wind 15 kt. Seas 4 ft.
.SUN...Variable wind 10 kt. Seas 4 ft.
.MON...NW wind 15 kt. Seas 9 ft.
.TUE...NW wind 20 kt. Seas 9 ft.

$$

PKZ752-221130-
Castle Cape to Cape Tolstoi out to 15 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...NW wind 15 kt in the evening becoming variable 10 kt.
Seas 3 ft. Rain.
.FRI...Variable wind 10 kt. Seas 2 ft. Rain.
.FRI NIGHT...Variable wind 10 kt. Seas 2 ft.
.SAT AND SAT NIGHT...W wind 15 kt. Seas 3 ft.
.SUN...W wind 15 kt. Seas 2 ft.
.MON...Variable wind 10 kt. Seas 1 foot.
.TUE...W wind 15 kt. Seas 4 ft.

$$

PKZ753-221130-
Castle Cape to Cape Tolstoi from 15 to 100 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...W wind 20 kt. Seas 7 ft. Rain.
.FRI...Variable wind 10 kt becoming W 20 kt in the afternoon. Seas
6 ft. Rain.
.FRI NIGHT...W wind 20 kt. Seas 7 ft.
.SAT...NW wind 15 kt. Seas 7 ft.
.SAT NIGHT...W wind 20 kt. Seas 6 ft.
.SUN THROUGH MON...W wind 15 kt. Seas 6 ft.
.TUE...W wind 20 kt. Seas 8 ft.

$$

PKZ754-221130-
Cape Tolstoi to Cape Sarichef out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY FRIDAY...

.TONIGHT...SW wind 15 kt. Seas 4 ft. Rain.
.FRI...W wind 25 kt. Seas 6 ft. Rain.
.FRI NIGHT...NW wind 20 kt. Seas 5 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 5 ft.
.SUN...W wind 20 kt. Seas 5 ft.
.MON THROUGH TUE...W wind 15 kt. Seas 4 ft.

$$

PKZ755-221130-
Cape Tolstoi to Cape Sarichef from 15 to 100 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY FRIDAY AND FRIDAY NIGHT...

.TONIGHT...SW wind 20 kt. Seas 6 ft. Rain.
.FRI...W wind 30 kt. Seas 10 ft.
.FRI NIGHT...W wind 20 kt. Seas 8 ft.
.SAT...NW wind 20 kt. Seas 7 ft.
.SAT NIGHT...W wind 25 kt. Seas 7 ft.
.SUN...W wind 20 kt. Seas 8 ft.
.MON...W wind 15 kt. Seas 5 ft.
.TUE...W wind 20 kt. Seas 7 ft.

$$

PKZ756-221130-
Port Heiden to Nelson Lagoon out to 15 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...W wind 15 kt in the evening becoming variable 10 kt.
Seas 5 ft. Rain.
.FRI...Variable wind 10 kt. Seas 2 ft. Rain.
.FRI NIGHT...NE wind 15 kt. Seas 4 ft.
.SAT...W wind 20 kt. Seas 4 ft.
.SAT NIGHT...SW wind 15 kt. Seas 5 ft.
.SUN THROUGH MON...W wind 15 kt. Seas 5 ft.
.TUE...W wind 20 kt. Seas 3 ft.

$$

PKZ757-221130-
Port Heiden to Nelson Lagoon from 15 to 60 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...W wind 15 kt. Seas 5 ft.
.FRI...Variable wind 10 kt. Seas 4 ft.
.FRI NIGHT...Variable wind 10 kt. Seas 5 ft.
.SAT AND SAT NIGHT...SW wind 15 kt. Seas 6 ft.
.SUN THROUGH MON...W wind 15 kt. Seas 6 ft.
.TUE...W wind 20 kt. Seas 5 ft.

$$

PKZ758-221130-
Nelson Lagoon to Cape Sarichef out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY FRIDAY...

.TONIGHT...S wind 20 kt. Seas 5 ft. Rain.
.FRI...W wind 25 kt. Seas 8 ft. Rain.
.FRI NIGHT...W wind 20 kt. Seas 6 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 8 ft.
.SUN...W wind 20 kt. Seas 7 ft.
.MON...W wind 15 kt. Seas 5 ft.
.TUE...W wind 20 kt. Seas 6 ft.

$$

PKZ759-221130-
Nelson Lagoon to Cape Sarichef from 15 to 70 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY FRIDAY...

.TONIGHT...S wind 20 kt. Seas 6 ft. Rain.
.FRI...W wind 25 kt. Seas 9 ft. Rain.
.FRI NIGHT...W wind 20 kt. Seas 7 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 9 ft.
.SUN...W wind 20 kt. Seas 8 ft.
.MON...W wind 15 kt. Seas 5 ft.
.TUE...W wind 20 kt. Seas 5 ft.

$$

PKZ770-221130-
Cape Sarichef to Nikolski Bering Side out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...S wind 30 kt. Seas 9 ft. Rain.
.FRI...W wind 25 kt. Seas 8 ft.
.FRI NIGHT...W wind 20 kt. Seas 6 ft.
.SAT AND SAT NIGHT...W wind 25 kt. Seas 8 ft.
.SUN...SW wind 20 kt. Seas 8 ft.
.MON THROUGH TUE...W wind 15 kt. Seas 5 ft.

$$

PKZ772-221130-
Cape Sarichef to Nikolski Bering Side from 15 to 85 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...S wind 30 kt. Seas 10 ft. Rain.
.FRI...W wind 25 kt. Seas 9 ft.
.FRI NIGHT...W wind 20 kt. Seas 7 ft.
.SAT AND SAT NIGHT...W wind 25 kt. Seas 10 ft.
.SUN...SW wind 20 kt. Seas 9 ft.
.MON...Variable wind 10 kt. Seas 6 ft.
.TUE...W wind 15 kt. Seas 6 ft.

$$

PKZ771-221130-
Unalaska Bay-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...S wind 20 kt becoming W 30 kt after midnight. Seas 3 ft
building to 5 ft after midnight. Rain.
.FRI...W wind 30 kt diminishing to 20 kt in the afternoon. Seas
4 ft.
.FRI NIGHT...W wind 10 kt. Seas 2 ft.
.SAT AND SAT NIGHT...W wind 15 kt. Seas 2 ft.
.SUN...SW wind 15 kt. Seas 2 ft.
.MON THROUGH TUE...W wind 10 kt. Seas 2 ft.

$$

PKZ773-221130-
Cape Sarichef to Nikolski Pacific Side out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...SW wind 30 kt. Seas 8 ft. Rain.
.FRI...W wind 30 kt diminishing to 20 kt in the afternoon. Seas
8 ft.
.FRI NIGHT...W wind 15 kt. Seas 5 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 6 ft.
.SUN...SW wind 20 kt. Seas 6 ft.
.MON...W wind 15 kt. Seas 4 ft.
.TUE...W wind 20 kt. Seas 5 ft.

$$

PKZ774-221130-
Cape Sarichef to Nikolski Pacific Side from 15 to 85 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...SW wind 30 kt. Seas 10 ft. Rain.
.FRI...W wind 30 kt diminishing to 20 kt in the afternoon. Seas
10 ft.
.FRI NIGHT...W wind 15 kt. Seas 7 ft.
.SAT AND SAT NIGHT...W wind 25 kt. Seas 7 ft.
.SUN...SW wind 20 kt. Seas 7 ft.
.MON...W wind 15 kt. Seas 6 ft.
.TUE...W wind 20 kt. Seas 7 ft.

$$

PKZ775-221130-
Nikolski to Seguam Bering Side out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...W wind 30 kt. Seas 9 ft.
.FRI...W wind 20 kt. Seas 8 ft.
.FRI NIGHT...W wind 15 kt. Seas 7 ft.
.SAT AND SAT NIGHT...W wind 25 kt. Seas 8 ft.
.SUN...SW wind 20 kt. Seas 8 ft.
.MON...Variable wind 10 kt. Seas 5 ft.
.TUE...W wind 15 kt. Seas 6 ft.

$$

PKZ776-221130-
Nikolski to Seguam Bering Side from 15 to 85 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...W wind 30 kt. Seas 10 ft.
.FRI...W wind 25 kt. Seas 9 ft.
.FRI NIGHT...W wind 20 kt. Seas 8 ft.
.SAT AND SAT NIGHT...W wind 25 kt. Seas 9 ft.
.SUN...SW wind 20 kt. Seas 8 ft.
.MON...Variable wind 10 kt. Seas 5 ft.
.TUE...W wind 15 kt. Seas 6 ft.

$$

PKZ777-221130-
Nikolski to Seguam Pacfic Side out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...W wind 30 kt. Seas 10 ft.
.FRI...W wind 20 kt. Seas 8 ft.
.FRI NIGHT...W wind 15 kt. Seas 6 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 7 ft.
.SUN...SW wind 20 kt. Seas 7 ft.
.MON THROUGH TUE...W wind 15 kt. Seas 6 ft.

$$

PKZ778-221130-
Nikolski to Seguam Pacific Side from 15 to 75 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...W wind 30 kt. Seas 11 ft.
.FRI...W wind 20 kt. Seas 9 ft.
.FRI NIGHT...W wind 15 kt. Seas 6 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 8 ft.
.SUN...SW wind 20 kt. Seas 7 ft.
.MON THROUGH TUE...W wind 15 kt. Seas 7 ft.

$$

PKZ780-221130-
Seguam to Adak Bering Side out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...W wind 25 kt. Seas 7 ft.
.FRI...SW wind 20 kt. Seas 6 ft.
.FRI NIGHT...SW wind 20 kt. Seas 7 ft.
.SAT...W wind 25 kt. Seas 8 ft.
.SAT NIGHT...W wind 20 kt. Seas 7 ft.
.SUN...SW wind 15 kt. Seas 5 ft.
.MON THROUGH TUE...SW wind 15 kt. Seas 5 ft.

$$

PKZ781-221130-
Seguam to Adak Bering Side from 15 to 85 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...W wind 30 kt. Seas 9 ft.
.FRI...SW wind 20 kt. Seas 9 ft.
.FRI NIGHT...W wind 15 kt becoming SW 25 kt after midnight. Seas
9 ft.
.SAT AND SAT NIGHT...W wind 25 kt. Seas 10 ft.
.SUN...SW wind 20 kt. Seas 7 ft.
.MON THROUGH TUE...SW wind 15 kt. Seas 5 ft.

$$

PKZ782-221130-
Seguam to Adak Pacific Side out to 15 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY TONIGHT...

.TONIGHT...W wind 25 kt. Seas 9 ft.
.FRI...SW wind 20 kt. Seas 7 ft.
.FRI NIGHT...W wind 15 kt. Seas 5 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 7 ft.
.SUN...SW wind 15 kt. Seas 5 ft.
.MON THROUGH TUE...SW wind 15 kt. Seas 6 ft.

$$

PKZ783-221130-
Seguam to Adak Pacific Side from 15 to 75 NM-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...W wind 25 kt. Seas 10 ft.
.FRI...SW wind 20 kt. Seas 8 ft.
.FRI NIGHT...W wind 15 kt. Seas 5 ft.
.SAT AND SAT NIGHT...W wind 20 kt. Seas 7 ft.
.SUN...SW wind 20 kt. Seas 6 ft.
.MON THROUGH TUE...W wind 15 kt. Seas 7 ft.

$$

PKZ784-221130-
Adak to Kiska Bering Side-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...SW wind 30 kt. Seas 11 ft.
.FRI...SW wind 20 kt. Seas 10 ft.
.FRI NIGHT...SW wind 25 kt. Seas 9 ft.
.SAT...W wind 25 kt. Seas 10 ft.
.SAT NIGHT...SW wind 20 kt. Seas 8 ft.
.SUN...SW wind 20 kt. Seas 6 ft.
.MON...W wind 15 kt. Seas 5 ft.
.TUE...SW wind 20 kt. Seas 5 ft.

$$

PKZ785-221130-
Adak to Kiska Pacific Side-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY...

.TONIGHT...W wind 25 kt. Seas 9 ft.
.FRI...SW wind 20 kt. Seas 8 ft.
.FRI NIGHT...W wind 20 kt. Seas 6 ft.
.SAT AND SAT NIGHT...SW wind 20 kt. Seas 7 ft.
.SUN...SW wind 20 kt. Seas 7 ft.
.MON THROUGH TUE...SW wind 15 kt. Seas 6 ft.

$$

PKZ786-221130-
Kiska to Attu Bering Side-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...SW wind 30 kt. Seas 15 ft.
.FRI...SW wind 25 kt. Seas 12 ft.
.FRI NIGHT...W wind 30 kt. Seas 11 ft.
.SAT...W wind 25 kt. Seas 9 ft.
.SAT NIGHT...SW wind 20 kt. Seas 7 ft.
.SUN THROUGH TUE...SW wind 20 kt. Seas 6 ft.

$$

PKZ787-221130-
Kiska to Attu Pacific Side-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...SW wind 30 kt. Seas 14 ft.
.FRI...SW wind 25 kt. Seas 9 ft.
.FRI NIGHT...SW wind 25 kt. Seas 9 ft.
.SAT...SW wind 25 kt. Seas 8 ft.
.SAT NIGHT...S wind 20 kt. Seas 6 ft.
.SUN THROUGH TUE...SW wind 20 kt. Seas 7 ft.

$$

PKZ766-221130-
Pribilof Islands Nearshore Waters-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...S wind 30 kt becoming W after midnight. Seas 9 ft.
Rain.
.FRI...W wind 20 kt. Seas 9 ft.
.FRI NIGHT...SW wind 25 kt. Seas 9 ft.
.SAT AND SAT NIGHT...W wind 25 kt. Seas 10 ft.
.SUN...SW wind 20 kt. Seas 8 ft.
.MON...Variable wind 10 kt. Seas 5 ft.
.TUE...W wind 15 kt. Seas 4 ft.

$$

PKZ760-221130-
Bristol Bay greater than 15 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...W wind 15 kt in the evening becoming variable less than
10 kt. Seas 5 ft.
.FRI...Variable wind less than 10 kt. Seas 2 ft.
.FRI NIGHT...Variable wind less than 10 kt. Seas 4 ft.
.SAT...W wind 10 kt. Seas 4 ft.
.SAT NIGHT...SW wind 10 kt. Seas 4 ft.
.SUN...SW wind 10 kt. Seas 4 ft.
.MON...W wind 10 kt. Seas 4 ft.
.TUE...W wind 20 kt. Seas 4 ft.

$$

PKZ761-221130-
Bristol Bay from Port Heiden to Cape Chichagof out to 15 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...W wind 15 kt in the evening becoming variable less than
10 kt. Seas 5 ft.
.FRI...Variable wind less than 10 kt. Seas 2 ft.
.FRI NIGHT...Variable wind less than 10 kt. Seas 3 ft.
.SAT AND SAT NIGHT...SW wind 10 kt. Seas 4 ft.
.SUN...SW wind 15 kt. Seas 4 ft.
.MON...W wind 10 kt. Seas 3 ft.
.TUE...NW wind 20 kt. Seas 3 ft.

$$

PKZ762-221130-
Bristol Bay from Cape Chichagof to Cape Pierce out to 15 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...NW wind 10 kt in the evening becoming variable less
than 10 kt. Seas 3 ft.
.FRI...Variable wind less than 10 kt. Seas 1 foot.
.FRI NIGHT...Variable wind less than 10 kt. Seas 2 ft.
.SAT...W wind 10 kt. Seas 2 ft.
.SAT NIGHT...S wind 10 kt. Seas 2 ft.
.SUN...S wind 10 kt. Seas 2 ft.
.MON...W wind 10 kt. Seas 2 ft.
.TUE...NW wind 15 kt. Seas 2 ft.

$$

PKZ763-221130-
Kuskokwim Delta and Etolin Strait out to 15 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...SE wind 10 kt increasing to 15 kt after midnight. Seas
2 ft.
.FRI...SE wind 15 kt. Seas 3 ft.
.FRI NIGHT...SE wind 15 kt becoming S after midnight. Seas 3 ft.
.SAT AND SAT NIGHT...S wind 15 kt. Seas 4 ft.
.SUN...S wind 10 kt. Seas 3 ft.
.MON...W wind 10 kt. Seas 3 ft.
.TUE...NW wind 15 kt. Seas 2 ft.

$$

PKZ764-221130-
Kuskokwim Delta from 15 to 80 NM-
241 PM AKDT Thu Sep 21 2023

.TONIGHT...S wind 20 kt. Seas 4 ft.
.FRI...SE wind 20 kt. Seas 6 ft. Rain.
.FRI NIGHT...S wind 15 kt. Seas 5 ft.
.SAT AND SAT NIGHT...SW wind 15 kt. Seas 6 ft.
.SUN...SW wind 15 kt. Seas 6 ft.
.MON...W wind 10 kt. Seas 5 ft.
.TUE...NW wind 15 kt. Seas 4 ft.

$$

PKZ765-221130-
North and West of Nunivak Island-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY FRIDAY...

.TONIGHT...SE wind 20 kt. Seas 6 ft. Rain.
.FRI...SE wind 25 kt. Seas 7 ft. Rain.
.FRI NIGHT...S wind 15 kt. Seas 6 ft.
.SAT...S wind 20 kt. Seas 7 ft.
.SAT NIGHT...SW wind 15 kt. Seas 7 ft.
.SUN...SW wind 15 kt. Seas 5 ft.
.MON THROUGH TUE...NW wind 15 kt. Seas 4 ft.

$$

PKZ767-221130-
Saint Matthew Island Waters-
241 PM AKDT Thu Sep 21 2023

...SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT...

.TONIGHT...SE wind 30 kt. Seas 11 ft. Rain.
.FRI...SW wind 25 kt. Seas 10 ft.
.FRI NIGHT...S wind 20 kt E of Saint Matthew Island... SW 30 kt W
of Saint Matthew Island. Seas 12 ft.
.SAT...SW wind 25 kt. Seas 10 ft.
.SAT NIGHT...W wind 20 kt. Seas 8 ft.
.SUN THROUGH TUE...N wind 15 kt. Seas 6 ft.

$$

NWS Anchorage, AK wrote its last area forecast discussion before this small craft advisory went out at Sep 21, 5:13 AM AKDT, 9 hours 28 minutes earlier.

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
513 AM AKDT Thu Sep 21 2023

.ANALYSIS AND UPPER LEVELS...

A deep but mostly stationary Kamchatka low is bringing a strong
front into the Central Aleutians this morning. Southerly small
craft winds, with higher gusts, span the length of the front, with
westerly small craft winds spilling into the western Gulf behind
the front. Precipitable water values are approaching 2 inches
ahead of the front, where the southerly flow has tapped into
deeper subtropical moisture to the south. This is promoting areas
of heavy showers tracking through the Western and Central
Aleutians. The front will push eastward throughout the day before
eventually weakening over the Alaska Peninsula. At the same time,
a ridge of high pressure over the eastern Gulf is becoming
squished between the approaching front and a broad trough to the
east stretching from interior Alaska down into the Gulf of Alaska.
Areas of low stratus and fog mixed with patches of clear skies
are the predominant conditions currently beneath the eastern
Bering ridge of high pressure. Southwest has largely cleared out
this morning with only a few very light isolated showers noted on
radar, and primarily over the higher elevations. Drier conditions
over Southwest are gradually spreading into Southcentral. The
trough over interior Alaska is being helped southward by a passing
shortwave trough digging to the southeast of Kodiak Island.
Ultimately, low pressure over Southcentral should meander into the
Gulf with high pressure to sit over the region through the end of
the week into the weekend.

&&

.MODEL DISCUSSION...
Models are in surprisingly good agreement with the pattern over
the next 48 hours. High pressure builds into Southcentral through
the end of the week as the previous low drops southward into the
Gulf of Alaska. A strong Aleutian front weakens over the Gulf of
Alaska as much of its associated energy is carried southward into
the North Pacific by a passing shortwave trough. The biggest
question mark entails a second passing trough that is forecast to
skirt south of the Central Aleutians Friday afternoon. The
Canadian models is deeper with the surface low and further north,
closer to Adak. Meanwhile, the GFS, NAM, and EC are in better
agreement with keeping the surface low more elongated and further
south of the Aleutians.

&&

.AVIATION...
PANC...Showers from overnight are forecast to gradually taper off
through the late morning hours. IFR ceilings will become
predominantly MVFR by midday, with developing VFR conditions due
to building high pressure later this evening.

&&

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

Rain is winding down across Southcentral this morning as
yesterday's system has weakened as it dips down into the western
Gulf and begins to merge with another system dropping south from
west-central Alaska towards the Bristol Bay and AKPen region.
This next system will allow for some scattered showers and general
unsettled weather to continue into the afternoon for Kodiak
Island and the western portion of Southcentral...including the
Kenai Peninsula, Prince William Sound, and the Anchorage Bowl up
towards the Mat-Su Valley. Models are in similar agreement with
today's system moving over Kodiak Island this afternoon before
pivoting into the central Gulf later this evening. Any lingering
showers will wind down late tonight through Friday morning.
Overall model consensus has high pressure starting to build into
the region Friday and Saturday resulting in drier weather and more
sunshine before the next low pressure system approaches. Friday
and Saturday morning temperatures look to be chilly for inland
areas, especially if minimal cloud cover is present. As such,
wouldn't be surprised to see areas like the Copper Basin dip into
the mid 20s or slightly lower either morning.

&&

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

An active pattern is expected to continue in the near term into
Friday for much of the outlook area, but a switch to more settled
conditions is on the horizon for the upcoming weekend as the
longwave pattern becomes substantially less amplified.

Looking at today across Southwest, much of the region will stay
under the influence of an upper trough and surface low shifting
east into the Gulf of Alaska. Gusty northwest winds on the western
side of this system will continue along and south of much of the
AKPen, enhanced partly by a compact shortwave trough dropping
south from Bristol Bay into the western Gulf. A few snow showers
will continue to follow this same trough across high terrain
around Bristol Bay and the Lower Kuskokwim Valley, but most
population centers will stay warm enough for any passing showers
to drop mainly rain.

From there, attention turns back to the main weather maker out
over the Bering Sea. A low near the north side of Kamchatka
continues to usher an occluding gale force front into the
western/central Bering this morning as a band of steady rainfall
follows along and ahead of the boundary, now moving past the central
Aleutians. This front is panning out about as forecast, but may
move just a touch faster than previous indications as it steadily
weakens and progresses towards the AKPen and eastern Bering
through Friday. In the wake of this front, very cool air aloft (as
cold as -30C at 500 mb) will move into the western Bering near a
negatively-tilted upper trough. This will once again extend a
pocket of elevated instability into the region, and thus,
isolated thunderstorms have been introduced to the far western
Bering Sea from late this afternoon through tonight.

By Saturday, the front will virtually fall apart as it moves into
the coast of Southwest while the parent low curves southeast into
the northern Bering Sea. This will keep widely scattered rain
showers around through Saturday evening across the eastern Bering,
Kuskokwim Delta and Bristol Bay, but an otherwise cool, calm and
quiet fall pattern will continue. Flow will meanwhile become very
zonal across the Bering Sea and Aleutians, and westerly winds at
the surface will likely struggle to meet small craft thresholds
just about everywhere by Saturday night.

&&

.LONG TERM FORECAST (Days 4 through 7; Sunday through
Wednesday)...

Long range guidance continues to cluster on a deep longwave trough
extending from near the pole south over Mainland Alaska, the Gulf
of Alaska and into the Northeastern Pacific and a second but
weaker longwave trough over the Western Aleutians, Western Bering
and Eastern Siberia. Model spread on the 20/12z model suite
remains minimal through the weekend and into Monday before
significant spread enters the suite by Tuesday. By mid week next
week the GFS attempts to build a ride over Western Alaska while
both the ECMWF and Canadian prefer a shortwave eroding a broad
upper level ride extending north out of the Northern Pacific into
the Aleutians. The ECMWF model indicates a deep trough developing
in the Western Aleutians by late Wednesday and Thursday of next
week. An ensemble approach with a heavier weighting of ECMWF is
preferred this forecast cycle for the extended forecast over any
of the deterministic models.

&&

SYNOPSIS AND MODEL DISCUSSION...BL
SOUTHCENTRAL ALASKA...PP
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AS
LONG TERM...CCC

In the hours before

Preliminary Local Storm Report...Summary
National Weather Service Anchorage AK
1201 PM AKDT Thu Sep 21 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0730 PM     Flood            3 SE Anchorage          61.18N 149.84W
09/20/2023                   Anchorage          AK   NWS Employee

            Lake Otis Parkway between Dowling and
            Providence road between 7:30 and 8:15pm on
            9/20. Both sides of the road (lower sides)
            had 2-6 inches of water and drains could not
            keep up with moderate rainfall. Hydroplaning
            was observed and puddles were deep enough to
            significantly slow the vehicle and reduce
            visibility due to large splashes.

0835 AM     Rain             5SE Anchorage           61.16N 149.80W
09/21/2023  M1.35 inch       Anchorage          AK   NWS Employee

            Rain started early Wednesday morning
            probably around 3 to 5 AM on Sept 20.
            Reported amount is for entire event, and
            rain just stopped for now.

0836 AM     Rain             3E Eagle River          61.31N 149.48W
09/21/2023  M0.80 inch       Anchorage          AK   Public

            Storm total from night of Sep 19 through
            morning of Sep 21. Approx 1100ft elevation.

&&

Small Craft Advisories in Alaska, 2023Every small craft advisory in 2023

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