Storm Warning 46, NWS Anchorage, AK

667 
FZAK62 PAFC 271210
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
310 AM AKST Wed Feb 27 2019

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.

PKZ499-280315-
310 AM AKST Wed Feb 27 2019
.SYNOPSIS FOR CENTRAL BERING SEA...

A 985 mb low at 58N 177W dissipates in the Gulf of Anadyr on Wed 
night. A 990 mb low near 47N 179W moves into Northern Kamchatka at
972 mb for Thu night. Its front pushes over the Aleutians and
Bering to the Southern Alaska Peninsula by Fri morning. 

$$

PKZ411-280315-
Bering Sea Offshore West of 180 and East of the International
Dateline-
310 AM AKST Wed Feb 27 2019

...GALE WARNING THURSDAY...

.TODAY...NW wind 10 to 15 kt. Seas 7 to 10 ft.
.TONIGHT...NW wind 15 to 30 kt. Seas 7 to 11 ft.
.THU...W wind 20 to 35 kt. Seas 9 to 14 ft. Freezing spray.
.THU NIGHT...W wind 15 to 30 kt. Seas 9 to 14 ft.
.FRI...SW wind 20 to 35 kt. Seas 7 to 11 ft.
.SAT THROUGH SUN...S wind 30 to 45 kt. Seas 15 to 23 ft.

$$

PKZ412-280315-
Bering Sea Offshore 171W to 180 and North of 56N-
310 AM AKST Wed Feb 27 2019

...STORM WARNING TONIGHT AND THURSDAY...

.TODAY...W wind 25 to 40 kt becoming NE 20 to 35 kt in the
afternoon. Seas 12 to 20 ft. Rain and snow.
.TONIGHT...E wind 35 to 50 kt. Seas 13 to 28 ft. Rain and snow.
.THU...SW wind 35 to 50 kt. Seas 18 to 30 ft.
.THU NIGHT...SW wind 10 to 25 kt. Seas 11 to 19 ft.
.FRI...SW wind 10 to 20 kt. Seas 7 to 11 ft.
.SAT THROUGH SUN...S wind 25 to 40 kt. Seas 12 to 20 ft.

$$

PKZ413-280315-
Bering Sea Offshore 171W to 180 and South of 56N-
310 AM AKST Wed Feb 27 2019

...STORM WARNING TONIGHT...

.TODAY...NW wind 20 to 35 kt becoming E 30 to 45 kt in the
afternoon. Seas 11 to 19 ft. Rain and snow.
.TONIGHT...E wind 35 to 50 kt becoming W after midnight. Seas 14
to 27 ft. Rain and snow.
.THU...W wind 30 to 45 kt diminishing to 15 to 30 kt in the
afternoon. Seas 13 to 21 ft.
.THU NIGHT...SW wind 10 to 20 kt. Seas 9 to 14 ft.
.FRI...SW wind 10 to 25 kt. Seas 6 to 10 ft.
.SAT THROUGH SUN...S wind 30 to 45 kt. Seas 10 to 18 ft.

$$

PKZ414-280315-
Bering Sea Offshore East of 171W-
310 AM AKST Wed Feb 27 2019

...STORM WARNING TONIGHT...

.TODAY...S wind 35 to 45 kt. Seas 14 to 22 ft. Rain.
.TONIGHT...SE wind 35 to 50 kt. Seas 16 to 26 ft.
.THU...S wind 30 to 45 kt becoming SW 20 to 35 kt in the
afternoon. Seas 14 to 22 ft. Rain.
.THU NIGHT...W wind up to 20 kt. Seas 9 to 15 ft.
.FRI...SW wind up to 15 kt. Seas 5 to 10 ft.
.SAT...S wind 15 to 30 kt. Seas 4 to 8 ft.
.SUN...SE wind 20 to 35 kt. Seas 9 to 14 ft.

$$

467 
FZAK62 PAFC 280041
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
341 PM AKST Wed Feb 27 2019

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.

PKZ499-281400-
341 PM AKST Wed Feb 27 2019
.SYNOPSIS FOR CENTRAL BERING SEA...

A 978 mb low at 51N 177W Wed afternoon moves into the northern
Bering at 973 mb by Thu afternoon. A new front approaches the
western Aleutians Fri afternoon. 

$$

PKZ411-281400-
Bering Sea Offshore West of 180 and East of the International
Dateline-
341 PM AKST Wed Feb 27 2019

...GALE WARNING THROUGH THURSDAY...

.TONIGHT...NW wind 15 to 30 kt increasing to 25 to 40 kt after
midnight. Seas 7 to 11 ft. Freezing spray.
.THU...W wind 25 to 40 kt. Seas 9 to 14 ft. Freezing spray.
.THU NIGHT...W wind 15 to 30 kt. Seas 9 to 14 ft. Freezing spray.
.FRI...SW wind 10 to 25 kt. Seas 9 to 12 ft.
.FRI NIGHT...S wind 30 to 45 kt. Seas 8 to 13 ft.
.SAT...SE wind 35 to 50 kt. Seas 14 to 22 ft.
.SUN...S wind 30 kt. Seas 16 to 25 ft.
.MON...SW wind 15 to 30 kt. Seas 13 to 17 ft.

$$

PKZ412-281400-
Bering Sea Offshore 171W to 180 and North of 56N-
341 PM AKST Wed Feb 27 2019

...STORM WARNING THROUGH THURSDAY...

.TONIGHT...E wind 35 to 50 kt, except N wind 35 to 45 kt W of 177W. 
Seas 16 to 25 ft. Rain and snow.
.THU...SE wind 40 to 55 kt E of 177W. NW wind 40 to 55 kt W of 177W.
Seas 19 to 30 ft.
.THU NIGHT...SW wind 20 to 35 kt becoming S 15 to 25 kt after
midnight. Seas 13 to 21 ft.
.FRI...SW wind 10 to 25 kt. Seas 9 to 12 ft.
.FRI NIGHT...S wind 10 to 20 kt. Seas 8 to 11 ft.
.SAT THROUGH SUN...S wind 30 to 45 kt. Seas 12 to 20 ft.
.MON...S wind 15 to 25 kt. Seas 12 to 17 ft.

$$

PKZ413-281400-
Bering Sea Offshore 171W to 180 and South of 56N-
341 PM AKST Wed Feb 27 2019

...STORM WARNING THROUGH THURSDAY...

.TONIGHT...E of 176W, SE wind 35 to 50 kt becoming SW after 
midnight. W of 176W, N wind 35 to 50 kt becoming W after midnight. 
Seas 14 to 27 ft. Rain and snow.
.THU...W wind 35 to 50 kt diminishing to 15 to 30 kt in the
afternoon. Seas 14 to 22 ft.
.THU NIGHT...SW wind 10 to 20 kt. Seas 10 to 16 ft.
.FRI...SW wind 15 kt. Seas 7 to 10 ft.
.FRI NIGHT...S wind 15 to 30 kt. Seas 8 ft.
.SAT...SE wind 35 to 50 kt. Seas 12 to 20 ft.
.SUN THROUGH MON...SW wind 20 to 35 kt. Seas 10 to 18 ft.

$$

PKZ414-281400-
Bering Sea Offshore East of 171W-
341 PM AKST Wed Feb 27 2019

...STORM WARNING TONIGHT...

.TONIGHT...SE wind 35 to 50 kt. Seas 15 to 25 ft.
.THU...S wind 30 to 45 kt diminishing to 20 to 35 kt in the
afternoon. Seas 14 to 22 ft.
.THU NIGHT...SW wind 10 to 20 kt. Seas 9 to 15 ft.
.FRI...SE wind up to 10 kt. Seas 6 to 11 ft.
.FRI NIGHT...W wind up to 15 kt. Seas 4 to 7 ft.
.SAT...S wind 15 to 30 kt. Seas 4 to 8 ft.
.SUN THROUGH MON...S wind 20 to 35 kt. Seas 8 to 16 ft.

$$

562 
FZAK62 PAFC 281233
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
333 AM AKST Thu Feb 28 2019

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.

PKZ499-010145-
333 AM AKST Thu Feb 28 2019
.SYNOPSIS FOR CENTRAL BERING SEA...

A 971 mb low at 56N 176W moves to 64N 177E at 972 mb Thu night. 
Its front moves into Southwest Alaska through Sat morning. A 969 mb 
low near 47N 164E Fri afternoon moves to 50N 166E at 960 mb by Sat 
morning. Its front moves over the Western Aleutians Sat morning.

$$

PKZ411-010145-
Bering Sea Offshore West of 180 and East of the International
Dateline-
333 AM AKST Thu Feb 28 2019

...GALE WARNING TODAY...

.TODAY...W wind 25 to 40 kt. Seas 9 to 14 ft. Freezing spray.
.TONIGHT...W wind 15 to 25 kt. Seas 9 to 13 ft. Freezing spray.
.FRI...SW wind 10 to 25 kt becoming 20 kt in the afternoon. Seas
10 ft. Freezing spray.
.FRI NIGHT...S wind 25 to 40 kt. Seas 8 to 12 ft.
.SAT THROUGH SUN...S wind 35 to 50 kt. Seas 14 to 27 ft.
.MON...SW wind 10 to 25 kt. Seas 9 to 16 ft.

$$

PKZ412-010145-
Bering Sea Offshore 171W to 180 and North of 56N-
333 AM AKST Thu Feb 28 2019

...STORM WARNING TODAY...

.TODAY...SW wind 35 to 50 kt. Seas 17 to 28 ft.
.TONIGHT...SW wind 15 to 30 kt. Seas 13 to 19 ft subsiding to 10
to 13 ft after midnight.
.FRI...SW wind 10 to 20 kt. Seas 10 ft.
.FRI NIGHT...S wind 10 to 20 kt. Seas 8 ft.
.SAT THROUGH SUN...S wind 30 to 45 kt. Seas 16 to 24 ft.
.MON...W wind up to 20 kt. Seas 9 to 14 ft.

$$

PKZ413-010145-
Bering Sea Offshore 171W to 180 and South of 56N-
333 AM AKST Thu Feb 28 2019

...GALE WARNING TODAY...

.TODAY...W wind 30 to 45 kt diminishing to 10 to 25 kt in the
afternoon. Seas 13 to 21 ft.
.TONIGHT...SW wind 10 to 20 kt. Seas 10 to 14 ft.
.FRI...SW wind 15 kt. Seas 9 ft.
.FRI NIGHT...S wind 15 to 30 kt. Seas 6 to 9 ft.
.SAT THROUGH SUN...S wind 35 to 50 kt. Seas 13 to 21 ft.
.MON...W wind 10 to 20 kt. Seas 8 to 11 ft.

$$

PKZ414-010145-
Bering Sea Offshore East of 171W-
333 AM AKST Thu Feb 28 2019

...GALE WARNING TODAY...

.TODAY...S wind 30 to 45 kt becoming SW 15 to 30 kt in the
afternoon. Seas 14 to 22 ft. Rain and snow.
.TONIGHT...W wind up to 15 kt. Seas 9 to 14 ft.
.FRI...SW wind up to 10 kt. Seas 8 ft.
.FRI NIGHT...SW wind 10 kt. Seas 4 to 7 ft.
.SAT THROUGH SUN...SE wind 25 to 40 kt. Seas 8 to 16 ft.
.MON...S wind 15 to 30 kt. Seas 10 to 13 ft.

$$

525 
FZAK62 PAFC 010043
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
343 PM AKST Thu Feb 28 2019

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.

PKZ499-011330-
343 PM AKST Thu Feb 28 2019
.SYNOPSIS FOR CENTRAL BERING SEA...

A front continues across the central Bering towards the Alaska 
Peninsula through Fri morning. A front approaches the western 
Aleutians by Fri afternoon. The associated low moves to 53N 169E
at 957 mb by Sat afternoon. 

$$

PKZ411-011330-
Bering Sea Offshore West of 180 and East of the International
Dateline-
343 PM AKST Thu Feb 28 2019

...GALE WARNING FRIDAY NIGHT...

.TONIGHT...W wind 15 to 25 kt. Seas 9 to 13 ft. Freezing spray.
.FRI...SW wind 10 to 25 kt. Seas 10 ft. Freezing spray in the morning.
.FRI NIGHT...S wind 10 to 20 kt becoming SE 25 to 40 kt after
midnight. Seas 7 to 12 ft.
.SAT...SE wind 35 to 50 kt. Seas 13 to 21 ft.
.SAT NIGHT...S wind 30 to 45 kt. Seas 20 to 28 ft.
.SUN...S wind 30 to 45 kt. Seas 17 to 30 ft.
.MON THROUGH TUE...S wind 10 to 25 kt. Seas 9 to 16 ft.

$$

PKZ412-011330-
Bering Sea Offshore 171W to 180 and North of 56N-
343 PM AKST Thu Feb 28 2019

.TONIGHT...SW becoming S wind 15 to 30 kt. Seas 11 to 19 ft.
.FRI...SW wind 10 to 20 kt. Seas 10 ft.
.FRI NIGHT...S wind 10 to 20 kt. Seas 7 to 10 ft.
.SAT...SE wind 30 to 45 kt. Seas 9 to 14 ft.
.SAT NIGHT...SE wind 30 to 45 kt. Seas 15 to 23 ft.
.SUN...S wind 30 to 45 kt. Seas 17 to 26 ft.
.MON THROUGH TUE...SW wind 10 to 25 kt. Seas 9 to 14 ft.

$$

PKZ413-011330-
Bering Sea Offshore 171W to 180 and South of 56N-
343 PM AKST Thu Feb 28 2019

.TONIGHT...SW wind 10 to 20 kt. Seas 9 to 14 ft.
.FRI...SW wind 15 kt. Seas 9 ft.
.FRI NIGHT...S wind 15 to 30 kt. Seas 8 ft.
.SAT...SE wind 35 to 50 kt. Seas 11 to 19 ft.
.SAT NIGHT...S wind 30 to 45 kt. Seas 16 to 24 ft.
.SUN...SW wind 25 to 40 kt. Seas 13 to 21 ft.
.MON...W wind 10 to 20 kt. Seas 8 to 11 ft.
.TUE...SW wind 15 to 25 kt. Seas 10 ft.

$$

PKZ414-011330-
Bering Sea Offshore East of 171W-
343 PM AKST Thu Feb 28 2019

.TONIGHT...W wind up to 15 kt. Seas 9 to 14 ft.
.FRI...SW wind up to 10 kt. Seas 5 to 9 ft.
.FRI NIGHT...SW wind 10 kt. Seas 6 ft.
.SAT...S wind 10 to 25 kt. Seas 4 to 7 ft.
.SAT NIGHT...SE wind 25 to 40 kt. Seas 8 to 13 ft.
.SUN THROUGH MON...S wind 25 to 40 kt. Seas 10 to 18 ft.
.TUE...SW wind 15 to 25 kt. Seas 9 to 13 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
434 AM AKST Tue Feb 26 2019

.ANALYSIS AND UPPER LEVELS...

There is a potent surface low near the coast of NE Russia south of
Anadyr with an elongated occlusion bisecting the north and east
Bering and pushing eastwards. There is a plume of moisture along
this occlusion and the radars at Nome/PAEC and Bethel/PABC are
picking up returns. As of 1319z or 4:19 AM AST the radar at King
Salmon/PAKC was dry as a bone. The pressure gradient is still
really tight with this system and the latest ASCAT/Advanced
Scatterometer pass has detected both storm and gale fore winds in
the Bering with this feature. The remainder of the frontal
boundary extends more than 1500 nautical miles south of the chain
into the North Pacific. There is a developing low southwest of
Adak. There is a dome of high pressure at the surface over the
Central Pacific and the upper level ridge is bisecting eastern
Alaska and the Gulf Of Alaska. With those clear skies in place
yesterday, the temperatures began to plummet once the sun set.
Numerous locations are in single digit or in below zero territory
this morning.

&&

.MODEL DISCUSSION...

With the prolonged residence of the longwave trough over the NW
Pacific and the Bering, the initialization parameter of choice has
been the ASCAT/Advanced Scatterometer wind field. Both the GFS
and NAM initialized well when comparing the placement of the
surface low near the NE coast of Russia and placement of the
anticyclone over the Gulf Of Alaska. The global models are in good
agreement with the major synoptic features through Thursday
morning which includes the domes of high pressure over the Gulf of
Alaska and Central Pacific, the new low impacting the Aleutians
and the remnants of Wutip in the East Pacific. The only potential
pitfall in the forecast package remains the fog prognostics over
southcentral. The models attempt to grapple with the microscale
features over Southcentral, but in reality there is a fair amount
of "nowcasting" that occurs with fog and low stratus.

&&

.AVIATION...
PANC...As of 1253z or 3:53 AM AST the sky conditions at PANC were
FEW002 and the VSBY was unrestricted. Once again, the Baldy
Webcam has detected an area of fog/low stratus near Knik Arm.
Additionally, the AVHRR/Advanced Very High Resolution Radiometer
(which is a satellite instrument) has detected fog and low status
over Cook Inlet west of Fire Island. The potential for fog or low
stratus moving over PANC is actively being monitored. For the 12z
TAF package, hedged with VCFG and a TEMPO for fog developing near
the aerodrome and the potential for low cigs or intermittent low
cigs this morning. If fog moves over PANC, conventional wisdom is
that conditions would improve early afternoon as the temperature
begins to climb. Other than fog or low stratus potential, expect
light winds and VFR conditions.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
(Tonight through Wednesday night)

The upper ridge entrenched over the Gulf and Southcentral is the
dominate synoptic feature. To a lesser degree, but still
noteworthy, is an inverted surface tough lingering near the North
Gulf Coast. In regards to the upper ridge, it shifts east some
over the next day or so. As it does so, flow in the low to mid
levels becomes southerly and will help push stratus up Cook
Inlet. So we are expected increasing low clouds to spread as far
as north as the Anchorage Bowl tonight and perhaps the extreme
southern Susitna Valley. The late February sun will likely help
break up the cloud deck over land areas during the day, but
cooling at night may allow low clouds to redevelop during the
overnight hours. Some fog will likely accompany the stratus
field.

The main contribution of the coastal surface trough will be to
enhance outflow conditions over the North Gulf and eastern Kenai
Peninsula tonight and Wednesday. So look for gusty outflow
conditions in favored locals (Copper River Delta, Thompson Pass,
Whittier, etc.).

&&

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

A persistent pattern will remain in place, with a strong omega
block ridge centered to the east of the region, and a series of
troughs moving from the western Bering into central portions of
it. In between these two features is a surface front that is
currently stalled along the Kuskokwim Delta south towards the
AKPEN. A few weak waves passing through will provide some burst
in ascent aloft. This combined with modest surface convergence
along the front will continue to foster showery type
precipitation near it. Further inland, drier conditions
will continue as these locations will experience more subsidence
(sinking air) and drying from the ridge of high pressure to the
east.

The stalled front will try to make progress further inland as an
upstream storm tries to "kick" it eastward. However, the high
pressure to its east will spell a quick death for it as
frontolysis (the dissipation of a front) ensues. Then, a pair of
lows moving through the Bering looks to send a couple of fronts
towards the coast through Friday, with re-newed precipitation
potential.

&&

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

As our current storm force low departs the region for eastern
Siberia, more of the same is on the way, as a pair of surface lows
race north from the Pacific. The first of which will enter the
west central portion of the chain later this evening, reaching a
position west of Saint Matthew Island by late Wednesday morning.
As it does so, a surface front will surge eastward towards the
coast before stalling. Widespread precipitation will accompany
both of these features, with sustained gale force winds
accompanying it, with the low dropping into the ~986-990 mb
range.

The second system, which will be the stronger of the two, will
cross the chain near Adak (like its predecessor) during the mid to
late afternoon hours on wednesday, passing through around 980mb.
This storm looks to have some tropical origins with its moisture
source, which will interact with a strong disturbance in the base
of a trough exiting the Sea of Okhotsk. This mid-level storm will
then get absorbed into the Bering trough, bringing the tropical
moisture northward. Typically when this occurs, strong low level
theta advection getting positioned under a cold Bering trough
tends to lead to strong surface cyclogenesis (low pressure
development), as indicated by the GFS and ECMWF models, which show
the storm bottoming out just under 970mb in the northwestern
Bering. As it does so, another surface front will move towards the
coast.

Given the increased potential instability with this storm, and
from a pattern recognition standpoint, we substantially increased
the winds to storm force. There's fairly high confidence as
virtually all models showed similar synoptic patterns at the
surface and in the mid levels, with the weaker NAM (9 mb weaker)
being discounted. This also was coordinated with the Fairbanks
office (AFG) after a good in house discussion. That said,
additional forecast refinements are likely over the next day or
so.

&&

&&

.MARINE (Days 3 through 5)...

We begin Wednesday with a strong pressure gradient in the Bering
Sea east of 175W. There remains a good amount of uncertainty
as we progress into Wednesday night and Thursday with the strength
and location of the low centers. This translates to some wind
direction and intensity uncertainty. At this point expect gale to
storm force wind over much of the Bering east of 175W much of
Wednesday and Thursday. Following this storm is a break in the
action as the next strong storm is not expected to impact the
western Aleutians and Bering Sea until late Friday. There is a
significant difference in model solutions for this storm, though
there is agreement that we will likely see gales, and possibly
storm force winds, over the western Bering Sea and western
Aleutians late Friday.

Persistent high pressure over mainland Alaska into the Gulf of
Alaska equates to generally benign conditions, sub gales Wednesday
through Friday.

&&

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

The strong upper high will continue to be the dominant feature
over mainland Alaska into the Gulf of Alaska while the Bering Sea
and Aleutians remain very active. Models and ensembles are in
good general agreement with this overall pattern.

Beginning Wednesday, the ridge will persist over eastern Alaska
as the broad deep upper trough is entrenched over the Bering Sea
Thursday through Saturday. A strong surface low treks north
through the central Bering Sea Wednesday leaving a broad weak
trough of low pressure across the Bering Thursday and Friday. This
is followed by a weak ridge poking into the eastern Bering Sea
late Friday into Saturday while yet another strong low moves into
the picture over the western Aleutians. Here the models diverge on
the location and intensity of this storm, but do agree on a tight
pressure gradient moving into the central to western Bering Sea.
This prefrontal pressure gradient then moves to the eastern Bering
Sea through the weekend, bringing with it gale to storm force
wind along with warmer low level air.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storm 170 173 174. Gale 172 411 412 413 414 165 175 176
179 180 181 185.

&&

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