Gale Warning 400, NWS Anchorage, AK

330 
FZAK61 PAFC 021148
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
348 AM AKDT Sat Sep 2 2017

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.

PKZ399-030115-
348 AM AKDT Sat Sep 2 2017
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...
A strong front will approach the Gulf from the south this evening,
then move to the north Gulf coast late Sun. 

$$

PKZ351-030115-
Gulf of Alaska Offshore North of 57N and West of 144W-
348 AM AKDT Sat Sep 2 2017

...STORM WARNING SUNDAY...

.TODAY...S wind 10 to 20 kt. Seas 6 ft.
.TONIGHT...SE wind 15 to 30 kt. Seas 4 to 7 ft building to 8 to
13 ft after midnight.
.SUN...E wind 30 to 40 kt becoming SE 35 to 50 kt in the
afternoon. Seas 11 to 21 ft. Rain.
.SUN NIGHT...SE wind 25 to 40 kt. Seas 14 to 19 ft.
.MON THROUGH TUE...SE wind 10 to 25 kt. Seas 9 to 14 ft.
.WED...S wind 20 kt. Seas 7 ft.

$$

PKZ352-030115-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
348 AM AKDT Sat Sep 2 2017

...STORM WARNING SUNDAY...

.TODAY...S wind 15 to 25 kt. Seas 5 to 8 ft.
.TONIGHT...SE wind 25 to 40 kt. Seas 8 to 13 ft.
.SUN...SE wind 35 to 50 kt. Seas 13 to 21 ft. Rain.
.SUN NIGHT...SE wind 20 to 30 kt. Seas 13 to 18 ft.
.MON...SE wind 15 to 30 kt. Seas 9 to 17 ft.
.TUE THROUGH WED...S wind up to 20 kt. Seas 7 to 12 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
501 AM AKDT Fri Sep 1 2017

.ANALYSIS AND UPPER LEVELS...
An upper level low persists centered west of Norton Sound with a
trough extending across the Kuskokwim and greater Bristol Bay area
to a secondary upper low centered over Shelikof Strait and the
Barren Islands. While scattered showers rotate around portions of
the upper lows, the more organized and widespread area of
precipitation is associated with the front/trough stretching
across the Kenai Peninsula and northern Gulf coast. A developing
north Pacific surface low south of the central Aleutians is
tracking east in phase with an upper trough extending into the
Bering from a vertically stacked low off of the Kamchatka
Peninsula.

&&

.MODEL DISCUSSION...
Although trending it slightly further south, models have come into
better agreement regarding the position and depth of the strong
low spinning up south of the Alaska Peninsula this weekend. The NAM
was the model of choice for the eastern domain while a NAM/GFS
blend was preferred for the west.

&&

.AVIATION...
PANC...Despite some lingering southeasterly flow, spill over
moisture making it over the Chugach Mountains will continue to
bring scattered showers and periods of MVFR ceilings this
morning. By midday as the upper trough lifts north and the flow
turns more southerly, shower coverage will increase somewhat
before tapering off overnight tonight through Saturday morning as
southeasterly flow increases again over the area, strengthening
downsloping.

&&

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

A cold upper low moving north across Southcentral today will bring
widespread showers. The cold air with this system will
sufficiently destabilize the atmosphere to produce a few
thunderstorms over the Susitna Valley and Copper River Basin.
Thunderstorms primarily will be concentrated near the Talkeetna
Mountains. Except for coastal locations, showers will become more
isolated tonight. Ridging building along the North Gulf
Coast/southern Copper River Basin, will produce brisk south winds
across the Basin this afternoon through evening.

On Saturday, a developing low and leading frontal trough
approaching the AK Pen will bring increasing winds and steady
rains to the western Gulf/Kodiak island by afternoon. By Saturday
night, rains will spread north to the Gulf coast/Kenai Peninsula
with areas in the lee of the Chugach Mountains predominately
downsloped. Winds will also increase to gale strength over the
Western Gulf/Kodiak Island with increased gap flows across the
mainland.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The persistent upper level trough that brought rain to much of
the area east of Bethel this week has now shifted east of most
areas, which will allow for a brief period of quiet weather today.
Clear skies overnight along with cold air moving in from the next
trough approaching from the north has brought the coldest
temperatures of the season to the area with most areas falling
into the 30's with a few areas along the Kuskokwim River flirting
with the freezing mark. These cold temperatures are not expected
to reoccur tonight as cloud cover and slightly warmer temperatures
will move through that area with the next upper low. This system
will bring another round of rain to most areas this afternoon into
Saturday. The most widespread and heaviest rainfall will however
hold off until Saturday as the upper trough begins to merge with a
much deeper system approaching from the Bering. Model agreement
has improved significantly in the last 24 hours, so there is now
good confidence that it will keep rainy weather over much of the
region this weekend. Eastern Bristol Bay will remain mostly dry
from this system as downsloping develops along with strong
easterly winds.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The next weather maker will continue moving through Western-
Central Bering today, with the most significant impact being rain
throughout the Aleutian/Pribilof Islands. This system will deepen
significantly this evening as it dips into the North Pacific, bringing
widespread gale force winds from Dutch Harbor eastward on
Saturday, which will then increase to storm force as it approaches
the AK pen on Sunday with widespread rain throughout the weekend.
The models are coming into a consensus with a more southerly low
track of this system, so it now appears that impacts from this
system will largely remain south of the Pribilof Islands.

&&

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

This forecast period the longwave pattern features broad troughing
with a closed low near St. Lawrence Island and a second closed low
south of the AK Peninsula. As time marches forward, the energy to
the north will be absorbed into the main center of cyclonic
circulation. All of the operational runs ping into a tight
pressure gradient as the low bombs out, with widespread
diffluence and moisture advection into southwest and south central
AK. There are some timing issues with the QPF placement and track
of the surface low, but generally expecting wet and unsettled
weather from this cyclone this forecast period.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 150 155 172.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...JR
SOUTHCENTRAL ALASKA...RMC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DEK
LONG TERM...PJS