Gale Warning 415, NWS Anchorage, AK

092 
FZAK62 PAFC 302327
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
327 PM AKDT Mon Jul 30 2018

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.

PKZ499-311315-
327 PM AKDT Mon Jul 30 2018
.SYNOPSIS FOR CENTRAL BERING SEA...
A 992 mb low near 56N 174W moves to 60N 173W at 999 mb by Tue 
afternoon, then moves into the northern Bering. A front approaches 
the western Bering early Tue morning...then dissipates as it moves 
into the central Bering Wed morning. Another strong front moves into 
the western Aleutians Wed. Its associated 994 mb low moves to 55N 
170E Wed afternoon.

$$

PKZ411-311315-
Bering Sea Offshore West of 180 and East of the International
Dateline-
327 PM AKDT Mon Jul 30 2018

.TONIGHT...NW wind 10 to 20 kt. Seas 8 ft. Patchy fog.
.TUE...S wind 10 to 20 kt. Seas 7 ft. Patchy fog.
.TUE NIGHT...S wind 10 to 20 kt. Seas 6 ft.
.WED...S wind 10 to 25 kt. Seas 4 to 8 ft.
.WED NIGHT...SW wind 15 to 30 kt. Seas 5 to 10 ft.
.THU THROUGH SAT...SW wind 10 to 25 kt. Seas 8 to 13 ft.

$$

PKZ412-311315-
Bering Sea Offshore 171W to 180 and North of 56N-
327 PM AKDT Mon Jul 30 2018

.TONIGHT...NW to E wind 10 to 25 kt. Seas 6 to 11 ft. Areas of fog. 
VSBY 1 NM or less.
.TUE...W wind 10 to 20 kt. Seas 6 to 9 ft. Areas of fog. VSBY 1 NM
or less.
.TUE NIGHT...SW wind 10 to 20 kt. Seas 4 to 7 ft. Patchy fog.
.WED...S wind 10 to 20 kt. Seas 4 to 7 ft.
.WED NIGHT...SW wind 10 to 25 kt. Seas 4 to 8 ft.
.THU THROUGH SAT...SW wind 10 to 25 kt. Seas 6 to 11 ft.

$$

PKZ413-311315-
Bering Sea Offshore 171W to 180 and South of 56N-
327 PM AKDT Mon Jul 30 2018

.TONIGHT...W wind 10 to 20 kt. Seas 7 ft. Patchy fog. VSBY 1 NM or
less.
.TUE...SW wind 20 kt. Seas 6 ft. Patchy fog. VSBY 1 NM or less.
.TUE NIGHT...S wind 25 kt. Seas 6 ft. Patchy fog.
.WED...SW wind 15 to 25 kt. Seas 6 ft.
.WED NIGHT...SW wind 20 to 30 kt. Seas 7 to 12 ft.
.THU THROUGH SAT...SW wind 20 to 30 kt. Seas 7 to 11 ft.

$$

PKZ414-311315-
Bering Sea Offshore East of 171W-
327 PM AKDT Mon Jul 30 2018

.TONIGHT...S wind 20 to 30 kt. Seas 9 to 13 ft. Areas of fog.
Rain. VSBY 1 NM or less.
.TUE...S wind 25 kt. Seas 8 to 11 ft. Areas of fog. VSBY 1 NM or
less.
.TUE NIGHT...SW wind 20 kt. Seas 8 ft. Patchy fog.
.WED...S wind 20 kt. Seas 7 ft.
.WED NIGHT...SW wind 15 to 30 kt. Seas 5 to 8 ft.
.THU THROUGH SAT...W wind 15 to 30 kt. Seas 5 to 10 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
438 PM AKDT Sun Jul 29 2018

.ANALYSIS AND UPPER LEVELS...
The low over the Bering has now become vertically stacked and is
currently centered northeast of Adak. Behind this low, a weak
shortwave is approaching the western Aleutians. To the east, a
ridge of high pressure is still in place over much of the Gulf.

Visible satellite imagery shows plentiful cloud cover over the
Bering and extending across the southern Mainland. Surface
observations indicate light scattered showers falling across the
Southwest coast and the northern AKPEN. Light showers are also
moving in over Prince William Sound this afternoon in response to
continued southerly flow over the Gulf and into Southcentral.

&&

.MODEL DISCUSSION...
Models remain in great agreement through Wed morning. The Bering
low continues to move north while the upper level ridge to the
east weakens and redevelops in the North Pacific. The main
forecast challenge this afternoon has been fog in an around
coastal areas and the timing of scattered showers.

&&

.AVIATION...
VFR conditions are expected to continue at PANC with the present
mid to high level stratus keeping the chances of lower stratus
MVFR to IFR stratus forming overnight slight. Southeasterly
Turnagain Arm winds are expected to bend north to PANC later
this afternoon and evening, though the core of the Turnagain Arm
jet will remain south of the terminal.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: Monday and
Tuesday)...
The primary weather pattern the next couple days will be a
general westward retreat of the clouds and moisture into Southwest
Alaska for the day Monday as the very persistent ridge over the
eastern Gulf noses into Southcentral. This should help keep the
Copper River Basin in particular under sunny skies, with a mix of
sun and clouds expected further west into the Mat-Su Valleys and
Anchorage for the day. Unfortunately for coastal communities, the
ridge will favor the continuation of fog and low stratus conditions
along the Gulf Coast. A weakening disturbance may bring some
light shower activity to Kodiak during the day as well. The gusty
winds through Turnagain Arm and along the Copper River ongoing
this afternoon will diminish overnight and become relatively calm
the next couple days.

Tuesday will start out similarly with the ridge persisting across
the Copper River Basin, allowing widespread 80s to develop through
that region during the afternoon. For Anchorage, the Mat-Su
Valleys, and the Kenai Peninsula, the lurking cool, cloudy,
unsettled weather over Southwest Alaska will begin to slowly
return eastward, especially during the afternoon hours. That
should limit afternoon high temperatures to the low to mid 70s
for most areas. Precipitation in the form of lines of showers
return for the evening hours into Tuesday night as a stronger
upper level shortwave moves in across the area. This will be the
start of a much wetter pattern for late week. More on that below.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
A strong pressure gradient between a 987mb low in the southern
Bering and a ridge in the Gulf of Alaska will continue to produce
gusty southerly winds over western Alaska through Monday night.
This low will weaken and fill in tomorrow as it begins a northward
progression into the central Bering. The weakening gradient will
allow southerly winds along the coast to diminish by early Tuesday
morning. Winds will then transition from southerly to westerly as
the low tracks into the northern Bering by Tuesday. The westerly
fetch will channel plenty of moisture toward southwest Alaska
through early next week. As a result, widespread clouds with
periods of showers will continue through Wednesday, both enhanced
by a series of shortwave troughs ejecting from the parent low
moving west to east across the Bering and over the southwest
mainland.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
A strong low north of Atka will begin a slow push to the north,
weakening and filling in over the northern Bering by early next
week. The tight pressure gradient between it and a ridge
downstream will continue to produce gale-force winds and rough
seas through tomorrow afternoon in an area from Unalaska to Port
Heiden to south of the Pribilofs. Tuesday, a weak ridge will build
across the central and eastern Aleutians. Upstream, a low
entering the western Bering will swing a front across the western
Aleutians. This will advance across the southern Bering and
Aleutian chain through Wednesday as the ridge retreats to the
south and east. Another developing low will push toward the
western Bering on Wednesday as ridge again builds over the central
Aleutians.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Beginning Wednesday night, the region will be under a west to
east zonal pattern with an upper level low situated over the
Norton Sound while a large upper ridge begins to build north
toward the Aleutian chain. As the ridge amplifies and builds
north into the Bering Sea Thursday, the upper low will slide
southeast across the southwest mainland and into Southcentral,
sending a stout front and widespread precipitation with it. Rain
should spread across Southwest and Southcentral Alaska through
the day on Thursday and into Friday. The low will slide into the
Gulf of Alaska and reform Friday, bringing heavy rain to the Gulf
Coast.

The upper ridge over the Bering will continue to build north and
somewhat east, setting up northerly flow over the western half of
the state, drawing down cooler air from the arctic with it. This
will also allow further disturbances over the arctic to slide
southeast across central and eastern mainland Alaska, though there
is some model disagreement as to how far east the ridge builds,
which will determine how far west precipitation will spread, with
Southcentral being on the dividing line for next weekend.

Out west, a strong upper jet riding over the top of the ridge
will tap into some subtropical moisture spreading heavy rain up
into the western Aleutians and Bering and eventually further east
as the ridge flattens. Winds will also increase over the area by
the end of next week leading to a rather stormy period for those
with marine interests.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning 170.

&&

SYNOPSIS AND MODEL DISCUSSION...KO/JR
SOUTHCENTRAL ALASKA...JPW
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TM
LONG TERM...KVP