Gale Warning 233, NWS Anchorage, AK

363 
FZAK62 PAFC 191200
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
400 AM AKDT Thu Mar 19 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.

PKZ499-200100-
400 AM AKDT Thu Mar 19 2020
.SYNOPSIS FOR CENTRAL BERING SEA...

High pressure builds over the eastern Bering and Aleutians through
late Fri night. A weak front moves over the northern Bering and
into Southwest Alaska by late Fri night.

$$

PKZ411-200100-
Bering Sea Offshore West of 180 and East of the International
Dateline-
400 AM AKDT Thu Mar 19 2020

...GALE WARNING TODAY...

.TODAY...SW wind 25 to 35 kt. Seas 16 to 23 ft. Snow.
.TONIGHT...SW wind 20 to 30 kt. Seas 11 to 17 ft.
.FRI...SW wind 20 kt. Seas 8 to 12 ft.
.FRI NIGHT...S wind 15 to 30 kt. Seas 8 ft.
.SAT...S wind 20 to 30 kt. Seas 9 to 14 ft.
.SUN...SE wind 20 to 30 kt. Seas 8 to 12 ft.
.MON...NE wind up to 15 kt. Seas 7 to 10 ft.

$$

PKZ412-200100-
Bering Sea Offshore 171W to 180 and North of 56N-
400 AM AKDT Thu Mar 19 2020

...GALE WARNING THROUGH TONIGHT...

.TODAY...SW wind 30 to 40 kt. Seas 20 to 26 ft.
.TONIGHT...SW wind 35 kt. Seas 14 to 21 ft.
.FRI...SW wind 25 kt. Seas 10 to 15 ft.
.FRI NIGHT...SW wind 10 to 20 kt. Seas 7 to 12 ft.
.SAT...S wind 10 to 25 kt. Seas 5 to 8 ft.
.SUN...SE wind 15 to 25 kt. Seas 6 to 11 ft.
.MON...E wind 10 to 25 kt. Seas 8 to 11 ft.

$$

PKZ413-200100-
Bering Sea Offshore 171W to 180 and South of 56N-
400 AM AKDT Thu Mar 19 2020

...GALE WARNING TODAY...

.TODAY...SW wind 25 to 35 kt. Seas 15 to 23 ft.
.TONIGHT...SW wind 20 to 30 kt. Seas 11 to 17 ft.
.FRI...SW wind 20 kt. Seas 8 to 13 ft.
.FRI NIGHT...SW wind up to 15 kt. Seas 5 to 10 ft.
.SAT...S wind up to 20 kt. Seas 4 to 7 ft.
.SUN THROUGH MON...E wind 10 to 25 kt. Seas 7 to 12 ft.

$$

PKZ414-200100-
Bering Sea Offshore East of 171W-
400 AM AKDT Thu Mar 19 2020

.TODAY...SW wind 20 to 30 kt. Seas 7 to 12 ft.
.TONIGHT...SW wind 20 to 30 kt. Seas 6 to 11 ft.
.FRI...SW wind 25 kt diminishing to 10 to 20 kt in the afternoon.
Seas 3 to 8 ft.
.FRI NIGHT...W wind 10 to 20 kt. Seas 3 to 8 ft.
.SAT...W wind up to 20 kt. Seas 3 to 6 ft.
.SUN THROUGH MON...SE wind 10 to 25 kt. Seas 3 to 8 ft.

$$

320 
FZAK62 PAFC 192256
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
256 PM AKDT Thu Mar 19 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.

PKZ499-201300-
256 PM AKDT Thu Mar 19 2020
.SYNOPSIS FOR CENTRAL BERING SEA...

High pressure build over the eastern Bering through Fri afternoon.
A front associated with a North Pacific low approaches the central
Aleutians Sat afternoon.

$$

PKZ411-201300-
Bering Sea Offshore West of 180 and East of the International
Dateline-
256 PM AKDT Thu Mar 19 2020

.TONIGHT...SW wind 15 to 30 kt. Seas 11 to 17 ft.
.FRI...SW wind 10 to 20 kt. Seas 9 to 12 ft.
.FRI NIGHT...SW wind 20 kt becoming 10 to 25 kt after midnight.
Seas 8 ft.
.SAT...S wind 15 to 30 kt. Seas 6 to 11 ft.
.SAT NIGHT...S wind 20 to 30 kt. Seas 8 to 13 ft.
.SUN...SE wind 15 to 25 kt. Seas 7 to 12 ft.
.MON...NE wind up to 15 kt. Seas 7 to 10 ft.
.TUE...SE wind up to 20 kt. Seas 6 ft.

$$

PKZ412-201300-
Bering Sea Offshore 171W to 180 and North of 56N-
256 PM AKDT Thu Mar 19 2020

.TONIGHT...SW wind 20 to 30 kt. Seas 14 to 20 ft.
.FRI...SW wind 15 to 25 kt. Seas 12 ft.
.FRI NIGHT...W wind 20 kt. Seas 9 ft.
.SAT...SW wind up to 20 kt. Seas 7 ft.
.SAT NIGHT...S wind 10 to 25 kt. Seas 5 to 8 ft.
.SUN...S wind 15 to 25 kt. Seas 5 to 10 ft.
.MON THROUGH TUE...E wind 10 to 25 kt. Seas 5 to 10 ft.

$$

PKZ413-201300-
Bering Sea Offshore 171W to 180 and South of 56N-
256 PM AKDT Thu Mar 19 2020

.TONIGHT...S wind 15 to 30 kt. Seas 10 to 17 ft. Snow.
.FRI...SW wind 10 to 25 kt. Seas 9 to 12 ft.
.FRI NIGHT...W wind 15 kt. Seas 8 ft.
.SAT...SW wind up to 20 kt. Seas 4 to 7 ft.
.SAT NIGHT...SE wind up to 20 kt. Seas 5 ft.
.SUN THROUGH MON...E wind 15 to 30 kt. Seas 7 to 12 ft.
.TUE...S wind up to 15 kt. Seas 6 ft.

$$

PKZ414-201300-
Bering Sea Offshore East of 171W-
256 PM AKDT Thu Mar 19 2020

.TONIGHT...SW wind 15 to 25 kt. Seas 7 to 12 ft.
.FRI...S wind 10 to 25 kt. Seas 5 to 10 ft. Rain.
.FRI NIGHT...W wind 10 to 20 kt. Seas 4 to 9 ft. Rain.
.SAT...NW wind up to 20 kt. Seas 3 to 7 ft.
.SAT NIGHT...SW wind up to 15 kt. Seas 3 to 5 ft.
.SUN THROUGH MON...SE wind 10 to 25 kt. Seas 3 to 8 ft.
.TUE...W wind 10 kt. Seas 3 to 6 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
512 AM AKDT Wed Mar 18 2020

.ANALYSIS AND UPPER LEVELS...

A strengthening upper level low over the western Gulf south of
Seward this morning will dig southeastward this morning as upper
level ridging quickly builds in over Southwest Alaska behind the
low. This will continue diminishing the snowfall that occurred
over Southcentral last night. Another upper level trough and
associated vertically stacked low is centered northwest of Attu,
causing strong winds across the central Aleutians.

Many areas where the upper level ridging is in place or building
are seeing mainly clear skies from Bethel east across the rest of
Southwest Alaska. The cloud cover and snowfall continue to shift
east, as skies are trying to clear along the Alaska range.
Plentiful lingering moisture behind the overnight snowfall is
keeping areas of low cloud cover lingering, especially along the
Kuskokwim Mountains, western Alaska Range, and through the Cook
Inlet region as well.

&&

.MODEL DISCUSSION...

Model agreement over the next several days is very good, lending
to high forecast confidence on the timing and intensity of the
upcoming snowfall event Thursday and Thursday night. Forecast
challenges will primarily focus on the temperatures the next few
days. Much of the model guidance appears to be too warm, and is
not taking into account the nearly 2 feet of snowpack that remains
over much of Southcentral. While the more than 12 hours of
daylight is certainly having an effect, and kept yesterday's
snowfall totals lower during the day, the deep snowpack is largely
counteracting that effect. Despite good model agreement on
Thursday's precipitation, it will be interesting to watch if the
model agreement that cold air will already be well in place before
the snowfall begins in Southcentral actually happens, as frequently
the cold air lags behind the snow.

&&

.AVIATION...
PANC...MVFR conditions, with very temporary IFR conditions will
persist over the next few hours, as lingering moisture from the
snowfall overnight and clearing skies potentially leads to patchy
fog and lower ceilings. Later on this morning, skies should be
more successful at clearing, especially with daytime heating.
Patchy fog may possibly develop again tonight. Otherwise VFR
conditions are expected. Light winds will persist into Thursday.
Snow returns with lower visibility and ceiling after 00Z Thursday
afternoon.

&&

.CLIMATE...

As of this writing, Anchorage is now at 82.8 inches of snow for
the snow season 2019-2020. This makes this winter the snowiest
since snow season 2012-2013. This is now the 20th snowiest snow
season on record, if no more snow were to accumulate, and the 13th
snowiest through March 17th. For the month of March, 16.2 inches
have fallen, which is the 11th snowiest March on record. This is
the 4th consecutive month of above normal snowfall. Thus far, 16
of the 17 days in March have been below normal temperature-wise,
with the one day, the first, being exactly normal. If the month
ends below normal, it will be the 3rd consecutive month of below
normal temperatures.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2/Today
through Thursday night)...

A storm system over the northern Gulf early this morning will
exit eastward this morning as a high amplitude upper level ridge
builds in from the west. Strong subsidence on the leading edge of
the ridge along with offshore flow will lead to quick end to any
remaining precipitation across Southcentral along with decreasing
clouds for most areas. Low level northwesterly flow will likely
hold clouds in longer for the northern Cook Inlet region (including
Anchorage and portions of the Mat-Su) as clouds bank up against
the west side of the Chugach and Kenai Mountains.

Cold air advection behind the low will lead to strong winds across
the western Gulf and Kodiak Island early on, with diminishing
winds as high pressure builds in through the day. Meanwhile,
gap winds along the north Gulf coast and western Prince William
Sound (including Seward/Resurrection Bay and Whittier/Passage
Canal) will rapidly increase this morning, followed by the Valdez
area and Copper River Delta this afternoon. While the cold air
advection is weak, favorable ingredients for the winds include
tight pressure gradients, uniform northerly flow through the
atmospheric column, and strong downward motion - helping to mix
stronger winds down to the surface. These winds will be fairly
short-lived, diminishing tonight from west to east as the ridge
moves overhead. Light winds inland could lead to some patchy fog
away from the Gulf, particularly areas surrounding Cook Inlet.

Upper level flow will remain progressive, with the ridge exiting
eastward Thursday and another trough moving in from the Bering
Sea. This trough will move quickly northeastward across
Southcentral Thursday afternoon through Thursday night, bringing
a very quick shot of precipitation. Temperatures will start out
fairly warm as precipitation first arrives, so there will likely
be a mix of rain and snow. However, colder air will rapidly move
in and should quickly change it to all snow. The trough will be
moving so fast that there won't be time for much snow accumulation.

&&

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

Clouds and scattered snow showers persist along the higher
terrain of the Kilbuck Mountains and the Alaska Range this
morning, aided by an upslope, northwesterly flow behind the
exiting trough. Elsewhere, a building ridge is allowing for a
trend toward clear and dry conditions today with the exception of
some patchy fog along the immediate coast and the Kuskokwim Delta
through mid-morning as winds diminish.

The ridge will quickly get pushed toward the east today, however,
as another frontal system advances toward the coast from the
Bering. Southerly winds will be on the increase from the AKPEN to
Kuskokwim Bay this evening with a mix of rain and snow by tonight.
The front quickly occludes as it pushes onshore tonight and
begins to fall apart as it reaches the Alaska Range by late
tomorrow. Warmer air out ahead of the front will provide for a mix
of rain and snow initially, but as the front advances east colder
air works in aloft, any mixed precipitation should change quickly
back to all snow. A couple of inches of snow is possible from the
Kuskokwim Delta south to the northern Bristol Bay coast. Farther
inland, along the middle and upper Kuskokwim Valley where colder
air will persist longer, 3 to 6 inches of snow are possible by
Thursday night.

Snow showers will persist through the end of the week, especially
for the northern half of Southwest Alaska as a series of
shortwaves allows a moist, westerly flow to continue. Farther
south, weak ridging will allow areas around Bristol Bay the AKPEN
to remain relatively dry through Friday. The exception will be
along the Alaska Range where upslope flow will produce a few
lingering clouds and snow showers.

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

A strong front will continue to produce widespread rainfall
across the central and eastern Bering today. Its associated low
will continue to lift north toward the Russian coast with gales
and storm-force gusts impacting the western Aleutians and Bering.
As this system lifts north, a weak ridge will set up over much of
the chain with light winds and minimal shower activity. A
shortwave then tracks across the Bering and Aleutian Chain
Thursday afternoon into Friday with a mix of rain and snow for
portions of the Chain and the southern Bering. Another ridge then
builds behind this system late Friday into Saturday yielding less
wind and only isolated showers.

&&

.MARINE (Days 3 through 5 Fri through Sun)...

Due to a triple point low in the northern Gulf Friday, expect
gale force winds to occur through channels including Shelikof
Strait, the Barren Islands and through gaps and passes on the
Pacific side of the Alaska Peninsula through Saturday morning.
Following this, there are indications that another triple point
low will spin up. If this plays out, expect similar winds in the
aforementioned channels through Sunday.

A gale force front over the Bering will continue to push
northeastward before it exits the Bering Friday. There is
moderate confidence that another front will enter the western
Bering Friday night. Forecast challenges include timing and
strength of the front. If the faster and stronger solution holds,
gale force winds will be possible in the western Bering through
Sunday.

&&

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

On Friday, an upper level ridge looks to move across the Bering
and into southern Alaska. Similar to last week, warm temperatures
and moist conditions will advect into the Aleutians and the Bering
Sea following the backside of the ridge through Saturday. Behind
this, an upper level trough splits this upper level ridge with
another upstream. This looks to bring westerly flow to the
Southwest which will propagate precipitation into the region
through Sunday. This active weather pattern will continue through
the middle of the week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storm Warning: 177, 412, 413.
Gale Warning: 130, 131, 165, 170, 172-176, 178-185, 411, 414.

&&

SYNOPSIS AND MODEL DISCUSSION...JPW
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TM
MARINE/LONG TERM...CK