Gale Warning 309, NWS Anchorage, AK

890 
FZAK61 PAFC 091133
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
333 AM AKDT Thu Apr 9 2020

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.

PKZ399-100245-
333 AM AKDT Thu Apr 9 2020
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...
High pressure builds across the Gulf through Fri afternoon. A front 
enters the southwest Gulf Fri afternoon and persists through Sat.

$$

PKZ351-100245-
Gulf of Alaska Offshore North of 57N and West of 144W-
333 AM AKDT Thu Apr 9 2020

.TODAY...NW wind 20 to 30 kt diminishing to 10 to 20 kt 
in the afternoon. Seas 8 to 12 ft.
.TONIGHT...N wind 10 to 15 kt. Seas 6 ft.
.FRI...E wind 10 to 15 kt. Seas 5 ft.
.FRI NIGHT...E wind 10 to 25 kt. Seas 4 to 7 ft.
.SAT...SE wind 15 to 30 kt. Seas 6 to 11 ft.
.SUN THROUGH MON...SE wind 10 to 20 kt. Seas 5 to 10 ft.

$$

PKZ352-100245-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
333 AM AKDT Thu Apr 9 2020

.TODAY...NW wind 10 to 20 kt. Seas 6 to 11 ft.
.TONIGHT...N to E wind 10 to 15 kt. Seas 4 to 8 ft.
.FRI...E wind 10 to 25 kt. Seas 4 to 8 ft.
.FRI NIGHT...E wind 15 to 30 kt. Seas 6 to 11 ft.
.SAT...SE wind 15 to 30 kt. Seas 8 to 13 ft.
.SUN THROUGH MON...SE wind 15 kt. Seas 5 to 9 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
1118 AM AKDT Wed Apr 8 2020

.ANALYSIS AND UPPER LEVELS...

The mature, vertically stacked low that helped to verify the
Winter Storm Warning in Kodiak overnight has moved into the
northern Gulf this morning. Conditions have improved for Kodiak as
the low has lifted northward, allowing for winds and snow to
start diminishing. The barrier jet that brought storm force winds
along the North Gulf Coast is beginning to weaken this morning as
a few snow showers continue to linger across the coastal locations
this morning.

An upper level ridge continuing to build into Southwest Alaska
has helped to keep the region relatively dry and clear overnight
through the morning hours today stretching all the way across to
the central Aleutians. Behind this surface high pressure, a front
associated with a weakening low is crossing over the western
Aleutians is moving towards Adak, bringing stronger winds and
showers as is progresses eastward.

&&

.MODEL DISCUSSION...

Models continue to be in good agreement with the overall synoptic
pattern, leading to higher forecast confidence in the short term.

&&

.AVIATION...
PANC...VFR conditions and northerly winds will persist. Expect
strong wind gusts to taper off by late morning.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Friday night)...

A vertically stacked low over the northern Gulf will exit to the
northeast Gulf this afternoon. Snow in the Prince William Sound
area will taper off this morning, as it spreads north and east
across the Copper River Basin. A secondary weak upper level trough
will cause light snow showers to linger in the Copper River Basin
through tonight with little or no accumulation. Meanwhile, weak
cold air advection behind the low combined with tight pressure
gradients between the exiting low and high pressure building in
from the Bering Sea will maintain windy conditions across the
Gulf through tonight before diminishing tomorrow. Similarly,
strong gap winds along the north Gulf coast and Prince William
Sound will peak this morning, then very slowly diminish this
afternoon through tomorrow.

High pressure will build overhead and lead to quiet conditions
across Southcentral and the Gulf Thursday through Friday. With
mostly clear skies both day and night, there will be a large
diurnal range in temperatures of roughly 35 degrees or more.
Thus, the freeze/thaw cycle will be in full force each day.
Expect an overall warming trend as the ridge builds in and the
arctic air mass in place moderates.

&&

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

Fair skies are expected today under weak high pressure. Temperatures
will remain approximately 10 degrees below average, climbing to
near 20 over the Kuskokwim Delta and 30 over the Bristol Bay
region. Clouds will increase Thursday as a warm front tracks over
Southwest Alaska. Most areas will remain free of precipitation,
however a quick 1 to 2 inches of snow cannot be ruled out across
the Kuskokwim Delta, north of the front. Mostly sunny skies and
slightly above-average temperatures are expected Friday as high
pressure builds in across the region in the wake of the front.

&&

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

Widespread snow showers are likely across the Pribilofs through
early Thursday along a warm front. Partial clearing is expected
thereafter, west of high pressure. Fair skies will persist across
the central and eastern Aleutians under the aforementioned high,
with showers developing Friday afternoon ahead of a warm
front. Active weather will continue across the western
Bering/Aleutians as a series of fronts move over the region.

&&

.MARINE (Days 3 through 5)...(Friday through Sunday)

Bering Sea/Aleutians…

A large area of low pressure will dominate much of the Bering Sea
and Aleutians on Friday, with its central pressure near 1000 mb
located over the western portions of the sea. Showery type
precipitation is a good bet. An attendant surface front will
bisect the east central Bering and Aleutians, but this front looks
to remain below gale force. This front moves rapidly north on
Saturday, away from the region. A north Pacific storm, in the
neighborhood of 970 mb, lifts north towards Shemya on Saturday
while remaining south of the island chain. Its associated surface
front does progress into the western and central Aleutians though,
with sustained gales possible.

Gulf of Alaska…

High pressure in control of the northern and eastern Gulf on Friday
moves eastward by Friday night, allowing a front to enter the
southwestern Gulf. This front reaches the northern and eastern Gulf
on Saturday, as a weak area of low pressure moves to a position
southeast of Kodiak Island. The front then moves ashore by Sunday
afternoon, with the weak low moving into the northern Gulf.
Northwesterly offshore flow then develops near the Barren Islands
and Kodiak Island.

&&

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

For the long term, there remains consistency for an upper level
ridge to remain present over the mainland of Alaska. While a
warming trend to near average remains evident every day through
Day 7, a somewhat unsettled pattern develops over the weekend.
Therefore, confidence is average through Sunday. After Sunday, the
models begin to diverge substantially leading to low confidence
for Monday and Tuesday.

Over the Bering and the Aleutians, both the GFS and ECMWF show a
similar upper level pattern with an upper trough over the North
Pacific corresponding to a strong low at the surface to the south
of the western Aleutians. The GFS keeps an extension of a weaker
upper level ridge across the Bering from the main ridge over the
mainland. This will help to keep the aforementioned system south
and push the trough underneath the ridge keeping it over the North
Pacific south of the Aleutian Chain. The ECMWF, however, weakens
the ridge over the Bering and allows the surface front with the
closed low to push into the western Bering early Sunday morning.
There is average confidence with the low in the North Pacific with
low confidence in the details of how this system progresses.
Further east, there is average confidence that another weak system
over the North Pacific will move northward toward Bristol Bay
Saturday keeping the weather unsettled across the eastern Bering

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gales 119 121 125 127-32 139 175 176 413.
         Storm 120 351 352.
         Heavy Freezing Spray 180.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...ALH
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...PD/MV