Gale Warning 308, NWS Anchorage, AK

854 
FZAK62 PAFC 082256
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
256 PM AKDT Wed Apr 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.

PKZ499-091245-
256 PM AKDT Wed Apr 8 2020
.SYNOPSIS FOR CENTRAL BERING SEA...

A 1001 mb low near 50N 169E moves to 53N 176E at 996 mb Thu
afternoon, then moves to 57N 175E at 1004 mb Fri afternoon.  A
front approaches the Pacific side of the Alaska Peninsula Fri.

$$

PKZ411-091245-
Bering Sea Offshore West of 180 and East of the International
Dateline-
256 PM AKDT Wed Apr 8 2020

.TONIGHT...S wind 10 to 20 kt. Seas 7 ft.
.THU...E wind 10 to 20 kt. Seas 6 ft. Rain.
.THU NIGHT...E wind 10 to 25 kt. Seas 6 to 10 ft. Snow.
.FRI...SW wind up to 20 kt. Seas 6 to 10 ft.
.FRI NIGHT...SW wind up to 15 kt. Seas 5 to 9 ft.
.SAT...S wind up to 15 kt. Seas 4 to 9 ft.
.SUN THROUGH MON...NE wind 10 to 20 kt. Seas 4 to 9 ft.

$$

PKZ412-091245-
Bering Sea Offshore 171W to 180 and North of 56N-
256 PM AKDT Wed Apr 8 2020

.TONIGHT...S wind 15 to 25 kt. Seas 4 to 9 ft. Snow with rain.
.THU...S wind 10 to 25 kt. Seas 6 to 10 ft. Rain.
.THU NIGHT...SE wind 15 to 30 kt. Seas 8 to 13 ft. Rain showers
and snow showers.
.FRI...S wind 15 to 30 kt. Seas 10 to 13 ft.
.FRI NIGHT...S wind 10 to 25 kt. Seas 6 to 11 ft.
.SAT THROUGH MON...E wind up to 15 kt. Seas 4 to 7 ft.

$$

PKZ413-091245-
Bering Sea Offshore 171W to 180 and South of 56N-
256 PM AKDT Wed Apr 8 2020

.TONIGHT...S wind 10 to 25 kt. Seas 7 to 10 ft. Rain.
.THU...SE wind 15 to 30 kt. Seas 7 to 10 ft. Rain.
.THU NIGHT...S wind 20 to 30 kt. Seas 10 to 13 ft.
.FRI...S wind 15 to 30 kt. Seas 7 to 12 ft.
.FRI NIGHT...S wind 10 to 20 kt. Seas 5 to 9 ft.
.SAT...SE wind 10 kt. Seas 5 ft.
.SUN THROUGH MON...E wind 10 to 20 kt. Seas 6 ft.

$$

PKZ414-091245-
Bering Sea Offshore East of 171W-
256 PM AKDT Wed Apr 8 2020

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

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
435 PM AKDT Tue Apr 7 2020

.ANALYSIS AND UPPER LEVELS...
The pattern is actually relatively quiet today with just 2
critical pieces to focus on. Before we get to the active weather,
mostly clear skies across Southcentral allowed temperatures to
drop all the way down -24F in the Copper River Basin this morning.
High pressure has continued to keep things quiet for much of
Southcentral today. So the first piece of the upcoming pattern is
a cold, closed low over the Eastern Bering. This feature is
actually drawing down some rather cold 850 mb (5,000') with
temperatures of about -19C. It is being supported by an upper
level jet streak at 300 mb (30,000') of 110kt from the northwest.
There are some heavier snow showers clipping parts of the YK-
Delta and the Alaska Peninsula associated with this feature.

Component #2 is a swath of moisture riding up through the North
Pacific on a trajectory just east of Kodiak Island. This moisture
is riding up on a fairly strong 120 kt 300mb jet moving from SW to
NE. There will actually be some significant jet interaction
(coupling) between these various parts of the jet today. This
strengthening upper level support will only serve to deepen a
developing surface low just east of Kodiak. This continues to be
the main story in weather for the next couple of days. A Winter
Storm Warning is in effect through tonight for Kodiak Island.

&&

.MODEL DISCUSSION...Overall across AK, models continue to handle
the synoptic pattern well. However, the key storm near Kodiak
Island continues to give the models fits. They have consolidated
around a solution where the surface low tracks just east of the
island. However, exactly where the low forms, whether or not it
takes on two centers, and where the heaviest QPF falls remain in
question. This is likely caused due to the interaction of a
compact low over the Eastern Bering, a coupling upper level jet,
and moisture coming from the data-void region of the N Pacific.
The global models (GFS and EC) continue to stick to their guns
keeping a consolidated low tracking the furthest to the east of
the island. However, the higher res models (to include the NAM and
the GEM-Regional) have trended further west with the low center
and depict the center in a more elongated fashion. The net effect
of the higher res solutions would be more warm air making it to
the eastern half of Kodiak Island and thus, limiting snow
accumulations. We have continued to stick towards the colder
solutions as they have been more consistent run to run. However,
the forecast for exact amounts at any given location, especially
near the coast, remain uncertain. Models have come into better
agreement ferrying the moisture with this storm further to the
east along the N Gulf Coast on Wed. So while Cordova could still
see some snow, it looks like Whittier through Valdez will be
mostly dry.

&&

.AVIATION...
PANC...VFR conditions and northerly winds will persist.

&&

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

A significant winter storm situated about 100 miles off the
southeast coast of Kodiak Island this evening will continue to
produce widespread precipitation and and strong easterly winds
over the western and northern portions of the Gulf through
Wednesday. The brunt of this storm will impact Kodiak Island with
heavy, wet snow and northerly wind gusts to 45 mph through early
Wednesday. Temperatures along the eastern shores of Kodiak Island
will continue to hover a couple degrees above the freezing mark
through this evening, allowing for the potential for a rain/snow
mix. However, as the low pulls away tonight, temperatures will
cool and any liquid precipitation will quickly change back over to
snow before ending by sunrise. A Winter Storm Warning remains in
effect for the island with 5 to 10 inches of snow, with locally
higher amounts, possible.

As the low lifts to the northeast, it will strengthen as its
front pushes toward the Southcentral coast. This will help
develop a barrier jet and increase easterly winds to storm-force
along the coast through the first part of Wednesday. Snow will
also accompany the front and push over Prince William Sound
tonight, bringing periods of snow for Cordova, Valdez, and
Thompson Pass. As the low and front move to the Southcentral
coast, northerly outflow winds will increase in response to the
tightening pressure gradient. Because of this, blowing snow is
possible for Thompson Pass, and perhaps even Cordova, although the
warmer temperatures along the coast will act to limit any
transportable snow. For the most part, snow amounts for these
locations will remain quite light due to a strong offshore flow
ahead of the storm keeping drier air in place near the surface.

Northerly outflow winds will again increase from west to east
across Southcentral beginning Wednesday in the wake of the low as
it tracks near Yakutat. Any lingering snow near Cordova will come
to an end late Wednesday as the surface low and accompanying
upper- level shortwave lift toward the Yukon. Conditions are then
expected to quiet down across Southcentral and the Gulf as high
pressure builds back in Wednesday night through Friday. An arctic
air mass will remain in place over the state, so temperatures
will continue to run a little below normal through the end of the
week, particularly for nighttime lows.

&&

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

Generally quiet weather is expected across Southwest Alaska
through Friday. The snow showers that occurred over some parts of
the area today are now weakening, with the most persistent ones
expected mainly through the Kuskokwim Mountains. High pressure
will build over the area on Wednesday, allowing for a bit more
sunshine through, especially inland and the further east you go.
Nudged high temperatures up a few degrees during the day Wednesday
to account for more expected sunshine. Late Wednesday night into
Thursday, a warm front will move north across the Bering, but the
main effects with it will be focused over the Kuskokwim Delta late
Wednesday night into Thursday. This could bring a couple inches
of snow to mostly coastal areas, with south to southwest winds
following behind the front. For now, however, the front appears
weak enough that impacts from this feature look to be minimal, but
any increases in strength could change that. Behind the front,
high pressure builds right back in, allowing sunshine to return
with temperatures warming back to near normal on Friday.

&&

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

A front moving across the western Aleutians currently will move
northeastward with time, reaching the northern Bering Wednesday
night. This will allow somewhat warmer temperatures to return to
the Aleutians. High pressure over the central Aleutians will shift
east across the Alaska Peninsula by Thursday. The parent low to
the aforementioned front moves into the western and central
Aleutians on Thursday. The low will eventually turn northward and
move across the western Bering through Friday. This will allow
southerly warmer wind flow to return to much of the eastern
Bering. A large North Pacific low will slowly make its way into
the Alaska Peninsula late on Friday, plunging the area back into
unsettled weather.

&&

.MARINE (Days 3 through 5)...(Friday through Sunday)

Bering Sea/Aleutians…

A large area of low pressure will dominate much of the Bering Sea
and Aleutians on Friday, with its central pressure near 1000 mb
located over the western portions of the sea. Showery type
precipitation is a good bet. An attendant surface front will
bisect the east central Bering and Aleutians, but this front looks
to remain below gale force. This front moves rapidly north on
Saturday, away from the region. A north Pacific storm, in the
neighborhood of 970 mb, lifts north towards Shemya on Saturday
while remaining south of the island chain. Its associated surface
front does progress into the western and central Aleutians though,
with sustained gales possible.

Gulf of Alaska…
High pressure remains over the northern and eastern Gulf on
Friday and then moves eastward by Friday night. This allows a
front to enter the southwestern Gulf. This front reaches the
northern and eastern Gulf on Saturday, as a weak area of low
pressure moves to a position southeast of Kodiak Island. The front
then moves ashore by Sunday afternoon, with the weak low moving
into the northern Gulf. Northwesterly offshore flow then develops
near the Barren Islands and Kodiak Island.

&&

.LONG TERM FORECAST (Days 3 through 7...Sat through Tue)...

For the long term, there remains some consistency for an upper
level ridge to persist over the mainland of Alaska. While a
warming trend to near average remains evident every day through
Day 7, a somewhat unsettled pattern develops over the weekend.
Therefore, confidence is average through Sunday. After Sunday, the
models begin to diverge substantially leading to low confidence
for Monday and Tuesday.

Over the Bering and the Aleutians, both the GFS and ECMWF show a
similar upper level pattern with an upper trough over the North
Pacific corresponding to a strong low at the surface to the south
of the western Aleutians. The GFS keeps an extension of a weaker
upper level ridge across the Bering from the main ridge over the
mainland. This will help to keep the aforementioned system south
and push the trough underneath the ridge keeping it over the North
Pacific south of the Aleutian Chain. The ECMWF, however, weakens
the ridge over the Bering and allows the surface front with the
closed low to push into the western Bering early Sunday morning.
There is average confidence with the low in the North Pacific with
low confidence in the details of how this system progresses.
Further east, there is average confidence that another weak system
over the North Pacific will move northward toward Bristol Bay
Saturday keeping the weather unsettled across the eastern Bering

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Warning 171.
MARINE...Gale 125 127 130 132-139 150.
		 Storm 119 120 131.
		 Heavy Freezing Spray 180 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MSO
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JW
MARINE/LONG TERM...MV