Storm Warning 27, NWS Anchorage, AK

829 
FZAK62 PAFC 281228
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
328 AM AKST Fri Feb 28 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.

PKZ499-290230-
328 AM AKST Fri Feb 28 2020
.SYNOPSIS FOR CENTRAL BERING SEA...

A 985 mb low at 48N 177E Fri morning moves to 55N 179E at 979 mb
Sat morning, then moves to 54N 173E at 986 mb Sun morning. Another
north Pacific low at 49N 176W at 974 mb Sat morning moves to 58N 
162W at 972 mb Sun morning. A pair of fronts moves through the central
Aleutians and AKPEN into the Bering Sat through Sun.

$$

PKZ411-290230-
Bering Sea Offshore West of 180 and East of the International
Dateline-
328 AM AKST Fri Feb 28 2020

...STORM WARNING SATURDAY...

.TODAY...E wind 15 to 25 kt becoming NE 25 to 40 kt in the
afternoon. Seas 6 ft building to 7 to 12 ft in the afternoon.
.TONIGHT...NE wind 30 to 45 kt. Seas 11 to 19 ft. Snow showers and
rain showers.
.SAT...N wind 35 to 50 kt. Seas 14 to 22 ft. Snow showers and rain
showers.
.SAT NIGHT...N wind 30 to 45 kt. Seas 14 to 27 ft.
.SUN...N wind 20 to 35 kt. Seas 12 to 20 ft.
.MON...N wind 15 to 25 kt. Seas 8 to 13 ft.
.TUE...N wind up to 15 kt. Seas 3 to 6 ft.

$$

PKZ412-290230-
Bering Sea Offshore 171W to 180 and North of 56N-
328 AM AKST Fri Feb 28 2020

...GALE WARNING TONIGHT AND SATURDAY...
...HEAVY FREEZING SPRAY WARNING TONIGHT AND SATURDAY...

.TODAY...E wind 10 to 20 kt increasing to 20 to 30 kt in the
afternoon. Seas 5 to 8 ft. Freezing spray.
.TONIGHT...E wind 30 to 45 kt. Seas 9 to 17 ft. Heavy freezing
spray near the ice edge. Snow showers and rain showers.
.SAT...SE wind 20 to 35 kt. Seas 9 to 17 ft. Heavy freezing spray
near the ice edge. Snow showers.
.SAT NIGHT...SE wind 25 to 40 kt. Seas 12 to 20 ft.
.SUN...E wind 15 to 30 kt. Seas 10 to 15 ft.
.MON THROUGH TUE...NE wind 10 to 25 kt. Seas 6 to 11 ft.

$$

PKZ413-290230-
Bering Sea Offshore 171W to 180 and South of 56N-
328 AM AKST Fri Feb 28 2020

...GALE WARNING THROUGH SATURDAY...

.TODAY...E wind 15 to 30 kt increasing to 30 to 45 kt in the
afternoon. Seas 4 to 7 ft building to 9 to 14 ft in the afternoon.
Snow and rain.
.TONIGHT...SE wind 30 to 45 kt becoming S 15 to 30 kt after
midnight. Seas 9 to 16 ft.
.SAT...S wind 25 to 40 kt. Seas 8 to 13 ft.
.SAT NIGHT...S wind 25 to 40 kt. Seas 13 to 19 ft.
.SUN...S wind 20 to 35 kt. Seas 10 to 18 ft.
.MON THROUGH TUE...N wind up to 20 kt. Seas 7 to 11 ft.

$$

PKZ414-290230-
Bering Sea Offshore East of 171W-
328 AM AKST Fri Feb 28 2020

...GALE WARNING TONIGHT...
...HEAVY FREEZING SPRAY WARNING TONIGHT...

.TODAY...E wind up to 15 kt increasing to 15 to 30 kt in the
afternoon. Seas in ice free waters 1 to 6 ft.
.TONIGHT...E wind 20 to 35 kt. Seas in ice free waters 3 to 8 ft.
Heavy freezing spray near the ice edge. Snow.
.SAT...S wind 15 to 30 kt. Seas in ice free waters 3 to 8 ft.
Snow.
.SAT NIGHT...S wind 20 to 35 kt. Seas in ice free waters 4 to 9
ft.
.SUN...SW wind 15 to 30 kt. Seas in ice free waters 5 to 10 ft.
.MON THROUGH TUE...N wind 10 to 25 kt. Seas in ice free waters 3
to 8 ft.

$$

035 
FZAK62 PAFC 282342
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
242 PM AKST Fri Feb 28 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.

PKZ499-291430-
242 PM AKST Fri Feb 28 2020
.SYNOPSIS FOR CENTRAL BERING SEA...

A 982 mb low at 53N 179W moves to 54N 179E and phases with a
stronger 970 mb low located at 49N 176W Fri night. This low
deepens to 960 mb and moves to 54N 174W Sat afternoon. The low 
then moves to 58N 166W at 965 mb Sat night and then moves inland 
over Southwest Alaska Sun afternoon.

$$

PKZ411-291430-
Bering Sea Offshore West of 180 and East of the International
Dateline-
242 PM AKST Fri Feb 28 2020

...GALE WARNING THROUGH SATURDAY NIGHT...

.TONIGHT...NE wind 25 to 40 kt. Seas 10 to 18 ft. Snow.
.SAT...NE wind 30 to 45 kt. Seas 13 to 21 ft.
.SAT NIGHT...NE wind 25 to 40 kt. Seas 14 to 22 ft.
.SUN...NE wind 30 kt. Seas 15 to 19 ft.
.SUN NIGHT...NE wind 25 kt. Seas 10 to 16 ft.
.MON THROUGH TUE...N wind up to 20 kt. Seas 5 to 10 ft.
.WED...E wind 10 to 25 kt. Seas 5 to 10 ft.

$$

PKZ412-291430-
Bering Sea Offshore 171W to 180 and North of 56N-
242 PM AKST Fri Feb 28 2020

...STORM WARNING SATURDAY NIGHT...

.TONIGHT...E wind 25 to 40 kt. Seas 8 to 16 ft. Snow and rain
showers.
.SAT...E wind 25 to 40 kt becoming NE 35 to 45 kt in the
afternoon. Seas 12 to 19 ft. Rain and snow.
.SAT NIGHT...NE wind 35 to 50 kt. Seas 14 to 22 ft.
.SUN...N wind 20 to 35 kt. Seas 12 to 20 ft.
.SUN NIGHT...NE wind 25 kt. Seas 8 to 13 ft.
.MON THROUGH TUE...NE wind 10 to 20 kt. Seas 4 to 9 ft.
.WED...E wind 15 kt. Seas 3 to 6 ft.

$$

PKZ413-291430-
Bering Sea Offshore 171W to 180 and South of 56N-
242 PM AKST Fri Feb 28 2020

...GALE WARNING THROUGH SATURDAY NIGHT...

.TONIGHT...SE wind 25 to 40 kt diminishing to 10 to 25 kt after
midnight. Seas 9 to 14 ft. Rain and snow.
.SAT...NE wind 25 to 40 kt. Seas 9 to 14 ft. Rain.
.SAT NIGHT...NW wind 25 to 40 kt. Seas 13 to 21 ft. Rain showers.
.SUN...N wind 15 to 30 kt. Seas 13 to 21 ft.
.SUN NIGHT...NE wind 10 to 25 kt. Seas 10 to 14 ft.
.MON THROUGH TUE...N wind 10 to 25 kt. Seas 7 to 11 ft.
.WED...E wind up to 15 kt. Seas 4 to 9 ft.

$$

PKZ414-291430-
Bering Sea Offshore East of 171W-
242 PM AKST Fri Feb 28 2020

...STORM WARNING SATURDAY NIGHT...
...HEAVY FREEZING SPRAY WARNING TONIGHT...

.TONIGHT...E wind 20 to 35 kt. Seas in ice free waters 4 to 9 ft.
Heavy freezing spray near the ice edge. Rain and snow showers.
.SAT...SE wind 25 to 40 kt. Seas in ice free waters 4 to 9 ft.
Rain and snow.
.SAT NIGHT...SW wind 40 to 55 kt. Seas in ice free waters 12 to
20 ft. Rain showers and snow.
.SUN...W wind 35 to 50 kt. Seas in ice free waters 13 to 21 ft.
.SUN NIGHT...NW wind 10 to 25 kt. Seas in ice free waters 6 to
11 ft.
.MON THROUGH WED...N wind 10 to 25 kt. Seas in ice free waters 3
to 7 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
410 AM AKST Thu Feb 27 2020

.ANALYSIS AND UPPER LEVELS...

An area of high pressure at the surface and aloft continues to
remain centered over eastern Siberia, while extending into western
Alaska. To it's south, a pair of lows in the Gulf continue to
bring precipitation to portions of the Gulf Coast, mainly from
Prince William Sound to Yakutat.

Further west, a pair of lows was influencing the weather. The
first system was riding the Aleutians in an eastward trek, with
the low currently near Nikolski. Another low just north of Shemya.
Both of these systems were bringing some isolated showery type
precipitation to the region.

&&

.MODEL DISCUSSION...

The models remain in good agreement through the weekend in the
overall synoptic pattern, with the biggest difference being
related to a north Pacific low that moves into the western Bering
Sea saturday morning. Here, the GFS continues to be the strongest
solution (like it has been most of the winter), as it portrays a
964 mb low. Conversely, the ECMWF (European) model is almost 10 mb
weaker, with the Canadian in between in strength but shows two
different low centers in that vicinity. The net difference here is
how much coverage of storm force sustained winds there will be.

They (the numerical models) do show good agreement that a
disturbance aloft will pinch off from this system and eject
eastward, with cyclogenesis (the development of a low pressure
system) commencing in the Gulf by Sunday morning, but once again
they disagree on the strength of the system by 10 mb. This
scenario then repeats itself by early next week. So in short, an
active pattern looks to return to southcentral and southwestern
Alaska, westward through the Aleutians and portions of the Bering
Sea.

&&

.AVIATION...

PANC...VFR conditions and light winds will prevail through the
forecast period.

&&

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

High pressure building in from the northwest is clearing out skies
over Southcentral Alaska. A weak low near Middleton Island is
still pushing a few clouds along the north Gulf coast with a line
of showers toward Cordova early this morning. This area of
showers and clouds should diminish today as the low pushes to the
Southeast and away from the area. This should leave mostly clear
and cold conditions across most of Southcentral through Friday
night.

Friday night is when the next system makes its way to Kodiak
Island from the Southwest and then into the remainder of
Southcentral Saturday. This is the system that is expected to
bring widespread snowfall to Southcentral, with the exception of
Kodiak which will warm up rapidly to turn precipitation type to
rain. The development of a triple point low near the Barren
Islands on Saturday will keep the warmer air from pushing farther
northward keeping precipitation all snow for the rest of
Southcentral.

&&

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

In the past 24 hrs, the temperatures at Bethel and Aniak have
plummeted by more than 10 degrees. The models continue to show
northerly flow in the boundary layer thereby ushering arctic air
into the region. The models look bone dry for Southwest for today
and Friday. A new storm is churning up in the north Pacific and
the leading edge of the precipitation shield will be in Bristol
Bay and Toksook Bay Saturday morning.

&&

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

There is an elongated surface low from Unalaska to the Western
Bering that will continue to weaken and become absorbed into the
longwave pattern on Friday. A developing low will come charging
out of the north Pacific toward the Western Aleutians. The models
continue to show slightly different tracks and intensities with
the surface low but there is high confidence that the Western and
Central Aleutians will see high end gale force winds and rough
seas. A Winter Storm Watch is in effect from Friday afternoon
through Saturday afternoon for Shemya and Amchitka. This storm is
projected to impact the entire chain.

&&

.MARINE (Days 3 through 5 Sat through Mon)...

A strong low in the Bering on Saturday will bring widespread gale
force winds across the Bering, Aleutians, and westward to near
Kodiak Island. Storm force winds are expected closer to the low
center, over the western Bering and central/western Aleutians. By
Sunday this system will weaken, with gales confined to the
central/western Aleutians and the western Bering. For the Gulf, on
Sunday and Monday westerly winds will be near gale force.

&&

.LONG TERM FORECAST (Days 4 through 7 Sun through Wed)...

On Sunday there will be a low in the Bering, with a trough
extending northeast into northern Alaska. Southwesterly flow aloft
will be over all of southern Alaska, extending westward through
the eastern and central Aleutians. Through Monday the models are
in fairly good agreement that the Bering low will weaken and
slowly drift south, while the northern Alaska trough drops
southward into southern Alaska. By Tuesday the deterministic
models diverge significantly on where the Bering low goes, and
also on how the upper level pattern develops over Alaska in
general. Therefore for Tuesday and Wednesday ensemble mean
forecasts are preferred, and forecast confidence is somewhat low.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch 191
MARINE...Gale Warning 173 174 175 176 177 178 411 413
         Heavy Freezing Spray warning 129 130 185 414

FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PJS
MARINE/LONG TERM...BL