Storm Warning 123, NWS Anchorage, AK

968 
FZAK62 PAFC 070038
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
338 PM AKST Mon Nov 6 2017

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.

PKZ499-071345-
338 PM AKST Mon Nov 6 2017
.SYNOPSIS FOR CENTRAL BERING SEA...
A front will move across the Bering and into the Western Mainland by
Tue morning.

$$

PKZ411-071345-
Bering Sea Offshore West of 180 and East of the International
Dateline-
338 PM AKST Mon Nov 6 2017

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...SW wind 20 to 30 kt increasing to 25 to 40 kt after
midnight. Seas 12 to 17 ft. Rain showers.
.TUE...SW wind 25 to 35 kt. Seas 13 to 17 ft. Rain showers and
snow showers.
.TUE NIGHT...SW wind 15 to 30 kt. Seas 10 to 15 ft. 
.WED...W wind 10 to 25 kt. Seas 8 to 13 ft.
.WED NIGHT...SW wind up to 20 kt. Seas 6 to 11 ft.
.THU THROUGH SAT...S wind 15 to 30 kt. Seas 9 to 14 ft.

$$

PKZ412-071345-
Bering Sea Offshore 171W to 180 and North of 56N-
338 PM AKST Mon Nov 6 2017

...GALE WARNING TUESDAY...

.TONIGHT...W wind 25 kt becoming SW after midnight. 
Seas 9 to 15 ft.
.TUE...SW wind 20 to 35 kt. Seas 9 to 17 ft. Rain showers.
.TUE NIGHT...SW wind 20 to 30 kt. Seas 12 to 16 ft.
.WED...SW wind 15 to 30 kt. Seas 10 to 15 ft.
.WED NIGHT...W wind 15 to 25 kt. Seas 9 to 13 ft.
.THU THROUGH SAT...SW wind 10 to 25 kt. Seas 8 to 13 ft.

$$

PKZ413-071345-
Bering Sea Offshore 171W to 180 and South of 56N-
338 PM AKST Mon Nov 6 2017

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...W wind 20 to 35 kt. Seas 7 to 12 ft. Patchy fog.
.TUE...SW wind 20 to 35 kt. Seas 8 to 13 ft.
.TUE NIGHT...SW wind 15 to 25 kt. Seas 9 to 13 ft.
.WED...SW wind 10 to 25 kt. Seas 8 to 11 ft.
.WED NIGHT...W wind up to 20 kt. Seas 8 ft.
.THU THROUGH SAT...S wind up to 20 kt. Seas 4 to 9 ft.

$$

PKZ414-071345-
Bering Sea Offshore East of 171W-
338 PM AKST Mon Nov 6 2017

.TONIGHT...S wind 15 to 30 kt becoming W after midnight. 
Seas 5 to 10 ft. Patchy fog. Rain.
.TUE...W wind 15 to 25 kt. Seas 5 to 9 ft.
.TUE NIGHT...SW wind 15 to 25 kt. Seas 6 to 11 ft.
.WED...SW wind 15 to 25 kt. Seas 8 to 11 ft.
.WED NIGHT...W wind 10 to 25 kt. Seas 9 ft.
.THU THROUGH SAT...W wind 10 to 25 kt. Seas 5 to 10 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
524 PM AKST Sun Nov 5 2017

.ANALYSIS AND UPPER LEVELS...
An amplifying upper level ridge over the eastern Bering Sea and
digging upper level trough over the eastern Interior and
Southcentral Alaska are the main weather features for the most of
the region today. In the far western part of the forecast area the
next upper level low is sitting over eastern Russia with a sharp
trough over Kamchatka. This is bringing a 150 kt jet at 250 mb
into the western Aleutians and western Bering Sea.

The trough over Southcentral Alaska is beginning to develop a cut
off low over Cook Inlet today as was expected. This low will then
head into the Gulf of Alaska tonight and help strengthen a
surface low that is in the western Gulf. This low is also being
strengthened by strong cold air advection coming through the
Alaska Peninsula and feeding into the low. The building high
pressure over the mainland part of the state, combined with this
intensifying Gulf low, will set the stage for some strong winds
along the Gulf coast and breezy north to northwest winds over the
rest of southern mainland Alaska.

&&

.MODEL DISCUSSION...
On the synoptic scale, the models are in good agreement through
most of the week. Details will therefore be the big issue for
determining the forecasts. In the short term this is the challenge
with the outflow winds on the North Gulf coast Monday into
Tuesday and in Valdez in particular. The higher resolution models
such as the NAM and Namnest are showing a setup conducive to mix
the stronger winds aloft down to the surface.
Farther out this week there will be some upper level waves moving
rather rapidly across the region. While the overall pattern will
keep mostly clear skies over much of the mainland, each of these
waves has a chance to bring a brief shot of precipitation as it
moves across. Details on the timing, strength, and available
moisture with each of the waves will be something to keep watching
this week.

&&

.AVIATION...
PANC...As the system that brought the snow moves out of the area,
the northerly winds will increase overnight and persist through
the day Monday. The winds will be strong enough to allow skies to
clear out and therefore VFR conditions are expected to persist as
soon as the winds kick up and push out the lingering low clouds.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Mon and
Tue)...
We will begin the transition from snow into potent offshore flow
to start the work week. Snow amounts panned out well across the
area with generally 3 to 5 inches across Anchorage with lesser
amounts in the Matanuska Valley, Eagle River, and the Anchorage
Hillside. Please see the Public Information Statement for more
details. The energy that helped to provide the lift for the snow
is now clearly evident diving into the Gulf of AK. The upper level
support combined with colder air moving over the still-quite warm
Gulf waters will result in rapid deepening of the surface low. As
a ridge of high pressure starts to tip into the region from the
Bering Sea, it will work in tandem with the low to allow the
pressure gradient to increase. Upper level support will follow
along on Mon helping to further enhance the mixing associated with
these winds. Strong north winds will be felt throughout the area.
On top of this, the typical gusty north to south channels (Seward,
Matanuska Valley, etc) will see even higher winds. Right now, it
looks like enough ingredients come together over the Valdez and
Thompson Pass area for some mountain wave activity. A high wind
warning has been issued to address this. Even though recent
snowfall was quite wet and had a high liquid water content, winds
could be strong enough to cause some blowing snow as the event
starts. The winds should peak late Mon night and then gradually
diminish on Tue. Even though temperatures will cool a couple of
degrees under the offshore flow, there will be widespread sunshine
across much of the area. Snow showers could linger a bit longer
over the Copper River Basin into midday Mon, but little to no
additional accumulation is expected.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The upper level ridge over the eastern Bering will shift east to
the Kuskokwim Delta coast late tonight, then tilt inland over
Southwest Alaska Monday and Monday night. Gusty northerly gap
winds through the Alaska Peninsula will continue tonight through
Monday morning then taper off Monday afternoon through Monday
night as the upper level ridge tilts overhead. An upper level
trough will follow Tuesday and Tuesday night pushing the ridge
east of the Alaska Range and bringing a cooler air mass onshore
and into Southwest Alaska.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A strong gale force front stretching from the western Aleutians
across the western Bering will swing into the central Aleutians
and central Bering tonight through Monday and then weaken as it
continues into the eastern Bering Monday night. The next frontal
system, which will be more of an open wave supported by a good bit
of cold air aloft, will swing across the western Aleutians Monday
evening and then continue east-northeast across the central and
eastern Bering Monday night through Tuesday.

&&

.LONG TERM FORECAST (Days 3 through 7: Wednesday through
Sunday)...

Offshore flow along the northern Gulf Coast will subside Tuesday
night as a transient ridge moves overhead. To the west however, an
approaching upper-level wave and a strengthening surface pressure
gradient will support increasing northwesterly outflow winds
along the Alaska Peninsula into the western Gulf Wednesday and
Thursday. Clouds and the chance for some very isolated snow
showers returns to Southcentral Thursday as a deepening trough
over the mainland sends a series of shortwaves southeast. Thursday
night, the trough will further amplify and a surface low will
develop in the northeastern Gulf. As the upper trough and the
surface low shift southeast, deep northerly flow will re-
establish itself over the Mainland. This setup supports the
potential for another strong outflow wind event along the northern
Gulf Coast towards the end of the week. In addition to the
wind potential towards the end of the week, expect temperatures to
rapidly cool Thursday night through Saturday over much of the
Mainland as an Arctic airmass is pulled southward on the backside
of the deep trough.

Gusty, showery weather will continue through Thursday over the
Bering Sea as the atmosphere continues to destabilize in response
to cold air advection. A ridge will build in Thursday night,
initiating a drying trend through the end of the week over the
Bering Sea.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale 120 126-128 130-132 136-140 150 175 177 178 185
411-413. Storm 351 352.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...MSO/PS
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...RSD