Gale Warning 340, NWS Anchorage, AK

078 
FZAK62 PAFC 072346
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
346 PM AKDT Thu May 7 2020

Offshore Waters Forecast for the Bering Sea

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.

PKZ499-081315-
346 PM AKDT Thu May 7 2020
.SYNOPSIS FOR CENTRAL BERING SEA...

A 1003 mb low at 57N 169E will move southwest tonight and
dissipate early Fri morning. A 972 mb low at 47N 164E late tonight
will move to 52N 168E Fri afternoon at 969 mb. This low will then
move to 57N 172E Sat afternoon.

$$

PKZ411-081315-
Bering Sea Offshore West of 180 and East of the International
Dateline-
346 PM AKDT Thu May 7 2020

...GALE WARNING FRIDAY AND FRIDAY NIGHT...

.TONIGHT...S wind 10 to 20 kt. Seas 6 to 9 ft.
.FRI...SE wind 30 to 45 kt. Seas 8 to 13 ft. Rain and snow.
.FRI NIGHT...SE wind 30 to 45 kt. Seas 12 to 20 ft. Rain.
.SAT...S wind 25 to 35 kt. Seas 15 to 22 ft.
.SAT NIGHT...S wind 20 to 35 kt. Seas 16 to 23 ft.
.SUN...S wind 15 to 30 kt. Seas 9 to 17 ft.
.MON THROUGH TUE...E wind up to 15 kt. Seas 6 to 9 ft.

$$

PKZ412-081315-
Bering Sea Offshore 171W to 180 and North of 56N-
346 PM AKDT Thu May 7 2020

...GALE WARNING FRIDAY NIGHT...

.TONIGHT...SE wind up to 15 kt. Seas 8 ft.
.FRI...E wind up to 20 kt increasing to 15 to 30 kt in the
afternoon. Seas 7 ft.
.FRI NIGHT...SE wind 30 to 45 kt. Seas 10 to 18 ft. Rain and snow.
.SAT...SE wind 25 to 40 kt. Seas 13 to 19 ft.
.SAT NIGHT...S wind 20 to 35 kt. Seas 12 to 20 ft.
.SUN...SE wind 10 to 25 kt. Seas 11 to 19 ft.
.MON THROUGH TUE...E wind up to 15 kt. Seas 5 to 8 ft.

$$

PKZ413-081315-
Bering Sea Offshore 171W to 180 and South of 56N-
346 PM AKDT Thu May 7 2020

...GALE WARNING FRIDAY AND FRIDAY NIGHT...

.TONIGHT...W wind 10 kt becoming S after midnight. Seas 8 ft.
.FRI...E wind 15 to 30 kt becoming SE 25 to 40 kt in the
afternoon.
Seas 7 to 12 ft. Rain.
.FRI NIGHT...SE wind 30 to 45 kt. Seas 9 to 17 ft. Rain.
.SAT...S wind 20 to 35 kt. Seas 10 to 18 ft.
.SAT NIGHT...S wind 15 to 30 kt. Seas 12 to 20 ft.
.SUN THROUGH MON...S wind up to 20 kt. Seas 9 to 14 ft.
.TUE...SE wind up to 15 kt. Seas 4 to 8 ft.

$$

PKZ414-081315-
Bering Sea Offshore East of 171W-
346 PM AKDT Thu May 7 2020

.TONIGHT...NE wind 10 to 20 kt. Seas 3 to 6 ft.
.FRI...NE wind 10 to 20 kt. Seas 7 ft.
.FRI NIGHT...SE wind 10 to 25 kt. Seas 6 ft.
.SAT...SE wind 15 to 30 kt. Seas 6 to 11 ft.
.SAT NIGHT...SE wind 15 to 30 kt. Seas 7 to 12 ft.
.SUN THROUGH TUE...SE wind up to 20 kt. Seas 6 to 11 ft.

$$

813 
FZAK62 PAFC 081144
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
344 AM AKDT Fri May 8 2020

Offshore Waters Forecast for the Bering Sea

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.

PKZ499-090145-
344 AM AKDT Fri May 8 2020
.SYNOPSIS FOR CENTRAL BERING SEA...

A 971 mb low near 47N 164E moves to 56N 172E at 963 mb late Fri 
night, then moves to near the Kamchatka Peninsula at 975 mb late
Sat night. An associated front over the Western Aleutians moves
into the Central Bering late Fri night, then dissipates in place
through late Sat night.

$$

PKZ411-090145-
Bering Sea Offshore West of 180 and East of the International
Dateline-
344 AM AKDT Fri May 8 2020

...STORM WARNING TODAY...

.TODAY...SE wind 25 to 40 kt increasing to 35 to 50 kt in the
afternoon. Seas 6 to 11 ft building to 9 to 17 ft in the
afternoon. Rain.
.TONIGHT...SE wind 30 to 45 kt becoming S 25 to 35 kt after
midnight. Seas 14 to 19 ft. Rain.
.SAT...S wind 25 to 40 kt. Seas 15 to 25 ft.
.SAT NIGHT...SW wind 20 to 35 kt. Seas 15 to 23 ft.
.SUN...S wind 15 to 30 kt. Seas 8 to 16 ft.
.MON...SE wind up to 20 kt. Seas 7 to 10 ft.
.TUE...NE wind 20 kt. Seas 6 to 9 ft.

$$

PKZ412-090145-
Bering Sea Offshore 171W to 180 and North of 56N-
344 AM AKDT Fri May 8 2020

...STORM WARNING TONIGHT...

.TODAY...E wind up to 20 kt becoming SE 20 to 35 kt in the
afternoon. Seas 6 to 10 ft.
.TONIGHT...SE wind 35 to 50 kt diminishing to 30 to 40 kt after
midnight. Seas 9 to 17 ft. Rain.
.SAT...S wind 25 to 40 kt. Seas 13 to 20 ft.
.SAT NIGHT...S wind 15 to 30 kt. Seas 14 to 22 ft.
.SUN THROUGH MON...E wind 10 to 25 kt. Seas 9 to 17 ft.
.TUE...E wind 10 to 20 kt. Seas 5 ft.

$$

PKZ413-090145-
Bering Sea Offshore 171W to 180 and South of 56N-
344 AM AKDT Fri May 8 2020

...STORM WARNING TODAY...

.TODAY...E wind 15 to 30 kt becoming SE 35 to 50 kt in the
afternoon. Seas 7 ft building to 8 to 13 ft in the afternoon.
Rain.
.TONIGHT...S wind 30 to 45 kt. Seas 9 to 15 ft. Rain.
.SAT...S wind 20 to 35 kt. Seas 13 to 21 ft.
.SAT NIGHT...S wind 15 to 30 kt. Seas 15 to 23 ft.
.SUN THROUGH MON...S wind up to 20 kt. Seas 8 to 13 ft.
.TUE...E wind 10 to 20 kt. Seas 4 to 8 ft.

$$

PKZ414-090145-
Bering Sea Offshore East of 171W-
344 AM AKDT Fri May 8 2020

...GALE WARNING SATURDAY...

.TODAY...NE wind 10 to 20 kt. Seas 6 ft.
.TONIGHT...SE wind 10 to 25 kt increasing to 20 to 30 kt after
midnight. Seas 5 to 8 ft.
.SAT...SE wind 20 to 35 kt. Seas 8 to 13 ft. Rain.
.SAT NIGHT...SE wind 10 to 25 kt. Seas 8 to 13 ft.
.SUN THROUGH TUE...E wind up to 20 kt. Seas 6 to 11 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
432 PM AKDT Wed May 6 2020

.ANALYSIS AND UPPER LEVELS...

A strong ridge is centered over the North Pacific near 30N/170E
(roughly 1500 miles south of the Aleutian Islands). A fairly
strong sub-tropical jet (~100 to 130 kt) extends over top of this
ridge and then dives southward into northeast Pacific. High
amplitude troughs with embedded closed lows are positioned over
the Western Bering and Northeast Pacific. As would be expected,
this is where the most significant weather is focused. The storm
over the western Bering has occluded and is in a weakening state.
It's associated occluded front is also weakening as it tracks
eastward across the Central Bering Sea and Aleutians. The
northeast low is more impressive, with cyclogenesis ongoing at the
triple point north of the original low center. This is in
response to a short-wave and jet streak moving up the east side of
the low/trough. This will ultimately develop into a major storm
system which will affect the Gulf beginning tonight. In the
meantime, there are a couple features rotating around the north
side of the trough, a weak vertically stacked low over the eastern
Gulf and a short-wave over the Southwestern Gulf. Weather impacts
from these are minimal.

Conditions over the southern mainland of Alaska are quiet, with
mostly clear skies underneath a ridge of high pressure. Satellite
imagery does show some cumulus clouds forming along the mountains
as the surface heats up. The short-waves passing south of the
ridge may provide just enough forcing to produce isolated showers
this afternoon, but most of the region will remain dry.

&&

.MODEL DISCUSSION...

Models are in excellent agreement with handling of large scale
features over the next few days and forecast confidence is
generally high.

&&

.AVIATION...

PANC...VFR conditions will persist. A Turnagain Arm wind will
develop this evening into the overnight hours in response to
tightening pressure gradients out ahead of a front cross the Gulf
of Alaska. While the core of Turnagain Arm winds will remain over
northern Cook Inlet, could see some gusty southeast winds affect
the terminal in response to warmer temperatures (and lower
pressure) over the Mat-Su. On Thursday, the Turnagain Arm wind
will bend solidly southward as it exits Turnagain Arm, with much
lower pressure to the south over the western Gulf. Normally, this
would mean the airport would remain out of the southeast winds.
However, this time of year with more surface heating and
instability, suspect the airport could see periods of southeast
winds.

&&

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

Sunny skies will continue today under high pressure. There remains
a slight chance of isolated thunderstorms across the northeastern
Copper River Basin this afternoon and evening as weak instability
is possible with daytime heating. Clouds will increase across
Southcentral Thursday as a strong front moves into the northern
Gulf. Rain will develop over Prince William Sound in the morning,
before tracking westward Thursday afternoon. Gusty easterly winds
will accompany the precipitation along the eastern Kenai
Peninsula and Kodiak Island. These winds will gradually diminish
into the weekend, though rain will continue. Little to no rain is
expected in Anchorage or the Mat-Su given the cross-barrier flow
pattern over the mountains.

&&

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

Isolated convection continues to percolate this evening and will
get cutoff once the sun sets. Thursday morning, an inverted trough
pushes across the Alaska Peninsula from the southeast bringing gusty
easterly to northeasterly winds to the region (AKPEN to Bristol
Bay). The winds will taper off by Friday morning. A warming trend
will continue through the end of the week with most interior
locations reaching highs in the low 60s.

&&

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

A front currently over the Western Bering continues to move
eastward this afternoon bringing rain and gusty southerly winds to
the Aleutian Chain. The ASCAT (Advanced Scatterometer) pass from
this afternoon detected gale force winds west of Attu Island.
However, this front is expected to weaken and the front will stall
near the Pribilof Islands Thursday. In its wake, a new potent low
will approach the Bering. This low will have a slightly different
track and the expectation is that widespread gales will sweep
most of the Bering. Rough seas and a widespread precipitation
shield will accompany this system.

&&

.MARINE (Days 3 through 5/Saturday through Monday)...

Bering Sea/Aleutians...

A strong low pressure system will be moving northeastward across
the Western Bering/Aleutians on Saturday. There is an increasing
confidence that widespread Gale force south-southwesterly winds
associated with this low will develop late Friday night into early
Saturday morning across the Western Bering/Aleutians. Confidence
also remains high with a second area of Gale force southerly winds
developing in the central Bering/Aleutians on Saturday. As the
low gradually weakens while moving northeastward, there is above
average confidence that these Gale force winds will ease Saturday
night into Sunday morning. A second low pressure system is
expected to approach the western Bering/Aleutians Monday
afternoon, though confidence in the wind forecast remains low as
there is a high degree of uncertainty in the intensity and
placement of this low.

Gulf of Alaska...

Forecast confidence generally remains low Saturday through Monday
due to discrepancies on the placement of synoptic scale features.
However, winds are expected to remain below gale force during the
period.

&&

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

The pattern will remain amplified Sunday through Wednesday as
upper level high pressure continues to extend northwestward from
the Canadian Rockies to the Alaskan North Slope. This pattern will
allow for warmer temperatures and overall dry weather. As the snow
continues to melt and sunlight becomes more abundant and longer in
duration, the potential for convective rain showers focused along
area mountains will increase. The upper ridging will help set the
stage for convection by minimizing the potential for widespread
cloud cover and allowing ample diurnal heating at the surface.

Upper troughing will persist across the Bering/Aleutians and
extend southeastward into the North Pacific. Due to this pattern,
the predominant storm track will be through the Bering and into
the North Pacific. A weakening low pressure system is expected to
move northwestward from the central Bering into Siberia Sunday
into Monday. A second low is expected to move eastward along the
Aleutians Monday afternoon through Wednesday. However, forecast
confidence remains low at this time due to large discrepancies in
the placement and intensity of this low.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC....Flood Warning 155 (Kuskokwim River at Kwethluk)
Flood Advisory 155 (Kuskokwim River Akiachak to Napakiak)
MARINE...Gale Warning 352, 351, 119, 120, 131, 130, 138, 137, 132, 150, 160, 155.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...SEB
SOUTHCENTRAL ALASKA...AP
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PJS
MARINE/LONG TERM...ED