Storm Warning 58, NWS Anchorage, AK

151 
FZAK61 PAFC 090013
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
313 PM AKST Thu Mar 8 2018

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.

PKZ399-091400-
313 PM AKST Thu Mar 8 2018
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...
A 967 mb near Kodiak Island moves inland over the Kenai Peninsula
early Friday morning. A secondary low complex with multiple low
centers forms over the western Gulf Friday evening and continues
through Saturday afternoon.

$$

PKZ351-091400-
Gulf of Alaska Offshore North of 57N and West of 144W-
313 PM AKST Thu Mar 8 2018

...STORM WARNING TONIGHT...

.TONIGHT...S wind 35 to 50 kt. Seas 16 to 24 ft. Rain and snow.
.FRI...S wind 20 to 35 kt. Seas 14 to 22 ft. Snow showers.
.FRI NIGHT...S wind 10 to 25 kt. Seas 9 to 16 ft.
.SAT...SE wind 20 kt. Seas 7 to 12 ft.
.SAT NIGHT...SE wind up to 15 kt. Seas 5 to 9 ft.
.SUN THROUGH TUE...NW wind up to 15 kt. Seas 4 to 9 ft.

$$

PKZ352-091400-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
313 PM AKST Thu Mar 8 2018

...STORM WARNING TONIGHT...

.TONIGHT...SW wind 35 to 50 kt. Seas 16 to 26 ft. Snow and rain.
.FRI...SW wind 20 to 35 kt. Seas 14 to 21 ft. Snow showers.
.FRI NIGHT...S wind 10 to 25 kt. Seas 13 to 16 ft.
.SAT...SE wind up to 20 kt. Seas 9 to 14 ft.
.SAT NIGHT...SE wind up to 15 kt. Seas 5 to 10 ft.
.SUN THROUGH TUE...NW wind up to 15 kt. Seas 3 to 8 ft.

$$

721 
FZAK61 PAFC 091249
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
349 AM AKST Fri Mar 9 2018

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.

PKZ399-100130-
349 AM AKST Fri Mar 9 2018
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 963 mb low at 59N 150W moves inland near 60N 152W Fri evening. A
front pushes into Southeastern Alaska for Fri afternoon. A 989 mb
low forms at 57N 152W Sat morning and moves to 58N 154W at 1004 mb
by Sun morning.

$$

PKZ351-100130-
Gulf of Alaska Offshore North of 57N and West of 144W-
349 AM AKST Fri Mar 9 2018

...GALE WARNING TODAY...

.TODAY...SW wind 30 to 40 kt becoming S 20 to 30 kt in the
afternoon. Seas 18 to 24 ft subsiding to 12 to 19 ft in the
afternoon. Snow showers.
.TONIGHT...S wind 10 to 25 kt. Seas 9 to 15 ft.
.SAT...SE wind 20 kt. Seas 7 to 12 ft.
.SAT NIGHT...SE wind up to 15 kt. Seas 5 to 9 ft.
.SUN...NW wind up to 15 kt. Seas 4 to 9 ft.
.MON THROUGH TUE...W wind up to 10 kt. Seas 4 to 7 ft.

$$

PKZ352-100130-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
349 AM AKST Fri Mar 9 2018

...GALE WARNING TODAY...

.TODAY...SW wind 20 to 35 kt diminishing to 15 to 25 kt in the
afternoon. Seas 14 to 22 ft. Snow showers.
.TONIGHT...S wind 15 to 30 kt diminishing to 10 to 20 kt after
midnight. Seas 14 ft.
.SAT...S wind up to 20 kt becoming SE in the afternoon. Seas 8 to
13 ft.
.SAT NIGHT...SE wind up to 15 kt. Seas 5 to 10 ft.
.SUN...W wind up to 10 kt. Seas 3 to 7 ft.
.MON THROUGH TUE...W wind up to 15 kt. Seas 3 to 8 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
417 PM AKST Wed Mar 7 2018

.ANALYSIS AND UPPER LEVELS...
A weakening upper trough is moving slowly east across Southcentral
this morning. This feature is wringing the remaining bite of
moisture out of the clouds in the form of flurries and local
freezing drizzle across the Kenai Peninsula to MAT-SU Valley
corridor. While light snow as falling across the Copper River and
snow showers along the North Gulf Coast.

Out West, an eastward marching front is spreading snow across the
Southwest Mainland and Bristol Bay and rain along the Alaska
Peninsula. Cold advection on the backside of the front shows up
well on satellite imagery with the presence of open cell cumulus
across much of the Bering Sea and western Aleutian Islands.

&&

.MODEL DISCUSSION...
Models still struggle some with the handling of the triple point
which moves to near Kodiak Thursday. All models except for the NAM
keep the low center south of the Kenai Peninsula through Midnight
Thursday night. By Friday morning, the NAM and GFS have the low
center over northern Cook Inlet while the ECMWF keeps the center
near Seward. While overall confidence is low, confidence is
increasing on significant snowfall is likely over the eastern
Kenai Peninsula and along Kachemak Bay.

&&

.AVIATION...
PANC...There will likely be a break in MVFR conditions this
evening. Otherwise, expect MVFR ceiling through tonight with local
IFR conditions possible during the morning and afternoon hours
Thursday.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The latest radar from Middleton Island (PAIH) has an elongated
band of showers bisecting the northern Gulf of Alaska spanning
from Chenega to southeast of the Copper River Delta. This band
will bring showers into Cordova but the dynamics supporting this
disturbance will continue to decay overnight.

A new storm is on the horizon. The latest satellite image has a
mature low pressure system moving into southwest AK. It's
virtually a perfect "T-bone structure" with the occlusion
extending towards Nome and the Bering Straight with the warm front
moving towards the AK PEN and Kodiak. The jet core is moving over
the Barren Islands and towards Kenai. As the forecast period
unfolds, the jet core will push south and a new triple point low
will develop south of the AK PEN. Expect an inverted trough to jut
northwards out of the surface low towards Kenai. The GFS rapidly
deepens this low having it drop more than 24 mb in 24 hrs from 15z
Thursday to 15z Friday, effectively bombing it out. The GFS hugs
the surface low close to the southern coast of the Kenai Peninsula
and then the GFS brings jumps the low west, which gets echoed by
the ECMWF. All the while, moisture is getting wrapped into the
Kenai Peninsula. Sensible weather highlights for Kenai include a
hefty amount of snow in the southern portion of Kenai, gusty
winds, blowing snow and avalanche potential. A Winter Weather
Advisory has been issued for portions of the Kenai Peninsula.

Kodiak will see strong west to northwest winds develop with the
strongest winds over Afognak and Shuyak Islands. Temperatures
will be close to or just above freezing.

The Anchorage Metro Area and the Mat-Su valleys will see the
only light snowfall from this storm as the latest runs of the
models indicating downsloping developing over the area.

Whittier and the Eastern Kenai Peninsula will see widespread
accumulations of a foot or more from this system with strong
onshore flow and temperatures generally remaining cold enough for
snow, however at this point warning level amounts are not expected.
Cordova and Valdez can also anticipate a fresh blanket of snow
with this new storm. Currently, model data suggests that the
temperatures will remain cold enough for precipitation to remain
all snow.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

A dynamic weather pattern is moving into Southwest Alaska this
evening as a leading edge warm front moves into the coast. This is
bringing snow with some mixed precipitation and rain to the
immediate Bristol Bay coast. This front moves inland toward the
Alaska Range then stalls tonight. This first shot with the front
will bring moderate snow from King Salmon eastward. But the bigger
story will then become a developing powerful triple point low
which will move over Kodiak Island and towards the southern Kenai
Peninsula. Strong warm air advection aloft will develop an
expansive deformation zone which will spread heavy snow over
eastern Bristol Bay into the lower Kuskokwim Valley. Strong
northwest winds with gusts as high as 35 MPH will accompany the
snow, with the heaviest accumulations around 6-12" with some
local 15" amounts near the Alaska Range. For this reason, a winter
storm warning will be active from 5 PM this evening to 9 PM
Thursday evening. The heaviest snow will occur through Friday
morning before shifting west and becoming more showery.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

A strong and fast moving warm front is crossing the Bering Sea and
will reach the Southwest coast by Thursday morning. Broad cyclonic
flow and strong cold air advection will ensue behind the front,
with storms over the northern Bering Sea and strong gale force
winds elsewhere. High seas of 25-33 feet will move toward the
Aleutian chain by Friday given the long fetch. Expect periodic
heavy snow showers given the very cold air mass aloft and the
strong cyclonic flow.

&&

.LONG TERM FORECAST (Days 3 through 7)...
An upper level low near Kodiak Island Friday evening will drop
southward through Sunday morning as the pattern further
amplifies. Another low will form just to the west of this low and
move northward, becoming the dominant low in the central Gulf by
Sunday afternoon. Further west, a large ridge over the Bering Sea
will slowly flatten through Sunday as a front pushes eastward
across the Bering and Aleutians. As this front reaches the
southwest Alaska coast on Sunday afternoon, the pattern will again
attempt to become more zonal. Exactly how this happens into early
next week is giving the models a bit of a struggle. This includes
how the models handle the Gulf low, which looks to weaken and then
possibly join the westerly flow as the it strengthens over the
state. Due to the model differences, the forecast issued by WPC
begins to tilt more strongly towards the ensemble means as the
week progresses.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Warning 161.
         Winter Weather Advisory 121.
MARINE...Storm 119 125 130 132 185.
         Gale 120 131 136 137 138 139 150 155 165 170-179.
         Heavy Freezing Spray 181 185

&&

SYNOPSIS AND MODEL DISCUSSION...RMC
SOUTHCENTRAL ALASKA...PS
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JA
LONG TERM...BL