Gale Warning 283, NWS Anchorage, AK

989 
FZAK61 PAFC 062241
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
241 PM AKDT Sat Apr 6 2019

Offshore waters forecast for the Gulf of Alaska West of 144W

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.

PKZ399-071245-
241 PM AKDT Sat Apr 6 2019
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A front over the northern Gulf will weaken Sun night. A 981 mb 
Pacific low will move to 56N 150W Sun morning then it will move
near 58N 150W at 990 mb Mon morning. The low will then move over
the Alaska Peninsula and dissipate Mon afternoon.

$$

PKZ351-071245-
Gulf of Alaska Offshore North of 57N and West of 144W-
241 PM AKDT Sat Apr 6 2019

.TONIGHT...E wind 30 kt. Seas 14 ft.
.SUN...E wind 25 kt diminishing to 10 to 20 kt in the afternoon.
Seas 11 ft.
.SUN NIGHT...SE wind 10 to 20 kt. Seas 6 to 10 ft.
.MON...S wind 10 to 20 kt. Seas 6 to 10 ft.
.MON NIGHT...S wind 10 to 20 kt. Seas 5 to 10 ft.
.TUE THROUGH THU...S wind up to 20 kt. Seas 5 to 10 ft.

$$

PKZ352-071245-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
241 PM AKDT Sat Apr 6 2019

.TONIGHT...E wind 10 to 25 kt. Seas 11 to 15 ft.
.SUN...NE wind 10 to 20 kt. Seas 9 ft.
.SUN NIGHT...SW wind up to 15 kt increasing to 10 to 25 kt after
midnight. Seas 6 to 9 ft.
.MON...SW wind 10 to 25 kt. Seas 7 to 11 ft.
.MON NIGHT...SE wind up to 15 kt. Seas 5 to 10 ft.
.TUE THROUGH THU...SW wind 10 to 25 kt. Seas 6 to 11 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
412 PM AKDT Fri Apr 5 2019

.ANALYSIS AND UPPER LEVELS...

The overall synoptic pattern remains fairly mild today. A ridge
is extending from the northern interior, along the northern
Bering into the western Bering. On the western edge of the ridge,
a longwave trough stretches from Siberia to the western
Aleutians. A shortwave stems from a vertically stacked low over
interior Alaska and is positioned over the Lower Kuskokwim Valley.
A westerly oriented shortwave is encompassing much of the Gulf of
Alaska and Southcentral Alaska.

At the surface, northerly flow is occurring over Southcentral
bringing cooler air into the region. A weak front in the northern
Gulf is pushing ahead of a low in the Pacific. This is creating
weak easterly flow and bringing in moisture to the northern Gulf.
Rain and snow showers are observed on both the Middleton Island
and Kenai radars.

Conditions over the Bering are fairly dry and calm with visible
satellite imagery depicting widespread stratus over the western
Bering. A surface shortwave over the southwestern mainland is
bringing some showers to the AKPEN and Bristol Bay areas.

&&

.MODEL DISCUSSION...
Models are in good agreement through Sunday. By Sunday, the
concern will focus on how the low in the Gulf develops, whether
it keeps the front offshore in the Gulf, or whether it pushes
into Prince William Sound and brings the barrier jet along with
it.

By midweek, the GFS and ECMWF each show a strong low moving into
the Bering Sea near Dutch Harbor/Unalaska. However, the ECMWF
takes a more northerly track. This will affect the Bristol Bay
region and should be monitored for the potential for high surf.

&&

.AVIATION...
PANC...VFR conditions will persist through tomorrow with one
caveat. There is a chance for marginal conditions for a short
period in the late night/easily morning hours as a disturbance
brings in a quick shot of light snow. Winds will remain light.

&&

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

The first of a series of upper-level shortwaves will track
westward across the Gulf tonight making its way to Kodiak Island
by late Saturday. Precipitation associated with this system will
begin to overspread coastal Southcentral tonight and linger
through Saturday. Due to the mainly westward progression of the
trough, the bulk of the precipitation is expected to remain along
the coast. Areas of light snow are possible from the Kenai
Peninsula north across the Cook Inlet and southern Mat-Su Valleys
overnight as temperatures will drop to near freezing prior to the
onset of the precipitation. Any accumulations will be very light
(half an inch or less) due, in part, to the precipitation
initially falling through a dry airmass currently in place.
Moreover, any accumulating snow will most likely be confined to
grassy surfaces as surface temperatures remain rather warm. As
temperatures rise tomorrow, a quick changeover to rain is expected
for all but the higher elevations. More rain and mountain snow
move in late Sunday into Monday as the main upper-level low in
the Gulf lifts north over Southcentral.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3/Friday
night through Monday)...

Look for another quiet day for southwest Alaska. Northeast flow
continues, keeping weather cool and dry with just a few clouds.
This will remain the case until tomorrow night. We are still
expecting an area of light snow and cloud cover to work its way
over the Alaska Range and into the interior of southwest. It will
slowly work its way to the coast on Sunday with some scattered
snow showers and fall apart as it progresses west. Overall, it
appears generally quiet weather for the region.

&&

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

A front is stretched directly over the Aleutian Islands. This is
the same front that was in the area yesterday and will continue to
decay in place into tomorrow with light rain showers and
low-level cloud cover. We are still expecting northerly flow to
setup tonight clearing clouds out of the region. This will also
cool temperatures a bit and allow freezing spray to work back into
northern parts of our forecast area.

&&

.MARINE (Days 3 through 5)...
(Monday through Wednesday)

...Coastal Waters of Southwest Alaska and the Bering Sea...

The main story in the medium range portion of the marine forecast
will be a pair of storms moving into the Bering from the north
Pacific, with the second system becoming fairly strong. On
Tuesday, the numerical models are in fairly good timing agreement
showing a low crossing the Aleutians near Adak in the ~980 mb
range, bringing seas to 8 to 13 feet near the low center, and
generally lower elsewhere. This system then dissolves Wednesday
morning across the northern Bering, as a rapidly intensifying low
moves in on its heels.

Although there's some model disagreement with speed, strength, and
track, the overall theme is for a storm somewhere near 950 mb to
pass between Adak and Atka Wednesday evening, bringing widespread
gales and some sustained storm force winds with it. At this time,
we expect storms most likely near the western through central
Aleutians and adjoining coastal waters, with gales elsewhere.
Seas will build into the 25 to 35 feet range south of the chain
and 10 to 20 feet on the north side.

Forecast Confidence: High pattern confidence, but details in wind
speeds still need to be ironed out.

...Gulf of Alaska...

A series of fronts will cross the Gulf during the mid-week, both
in a southwest to northeast fashion. The first of which will be
accompanied by an area of low pressure and and attendant front
entering the southwestern Gulf Monday afternoon. Winds will top
out at storm force with seas generally less than 10 feet. These
features then move into the northeastern and Panhandle region
Tuesday afternoon, with a transient area of high pressure building
across the area in its wake. A front of similar strength then
crosses the region on Tuesday and Wednesday.

Forecast Confidence: Average

&&

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

A fairly active pattern looks to take shape for much of the work
week with a series of fronts and areas of low pressure crossing
the region. Each storm system and associated front will bring
rounds of precipitation and some gusty coastal winds. The
strongest winds and heaviest precipitation will be found across
the west-central Aleutians eastward toward the AKPEN on
Wednesday as a strong area of low pressure moves into this area
before lifting into the eastern Bering. Numerical guidance
continues to struggle with the strength of the system on
Wednesday which affects the overall pattern from that point
onward. From this point, divergence increases in the numerical
solutions which results in lower forecast confidence.

Forecast Confidence: Average

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...RA / EZ
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BB
MARINE/LONG TERM...PD