Gale Warning 12, NWS Anchorage, AK

597 
FZAK61 PAFC 141252
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
352 AM AKST Sun Jan 14 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.

PKZ399-150200-
352 AM AKST Sun Jan 14 2018
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...
A 983 mb low near 55N 142W Sun night will move to 60N 146W at 987 mb
Mon morning, then move inland Mon afternoon. A front will move into 
the southeastern Gulf Mon afternoon then move into the northern Gulf
Mon night. The associated low will move to 56N 146W at 978 mb Tue 
morning.

$$

PKZ351-150200-
Gulf of Alaska Offshore North of 57N and West of 144W-
352 AM AKST Sun Jan 14 2018

.TODAY...SE wind 10 to 25 kt. Seas 15 to 18 ft.
.TONIGHT...NE wind up to 20 kt becoming NW after midnight. Seas
15 ft. Rain.
.MON...W wind 10 to 20 kt becoming NE up to 15 kt in the afternoon. 
Seas 13 ft.
.MON NIGHT...NE wind 15 to 30 kt. Seas 11 to 15 ft.
.TUE THROUGH WED...SE wind 15 to 30 kt. Seas 8 to 16 ft.
.THU...N wind 15 kt. Seas 8 to 12 ft.

$$

PKZ352-150200-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
352 AM AKST Sun Jan 14 2018

.TODAY...SE wind 15 to 30 kt diminishing to up to 20 kt in the
afternoon. Seas 16 to 19 ft.
.TONIGHT...E wind up to 15 kt becoming W after midnight. Seas 15
ft.
.MON...SW wind 10 kt becoming E in the afternoon. Seas 11 to 14
ft. Rain.
.MON NIGHT...NE wind 15 to 30 kt. Seas 10 to 15 ft.
.TUE...SW wind 15 to 30 kt. Seas 10 to 16 ft.
.WED THROUGH THU...NW wind 10 to 25 kt. Seas 7 to 12 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
639 AM AKST Sat Jan 13 2018

.ANALYSIS AND UPPER LEVELS...

The trough-ridge pattern set up over southern Alaska and the north
Pacific continues to amplify as the trough digs all the way down
to 35N. Then a ridge over the western half of North America
returns a nearly due south to north flow through the Gulf into
Southcentral. Warm air associated with the ridging continues to
move northward into Southcentral. The vertically stacked low
south of Sand Point is providing the energy, and cold air to
produce strong warm fronts that are causing strong winds, and
periodically heavy precipitation.

Temperatures continue to warm over the area, reaching the upper
30s to lower 40s at coastal communities like Kodiak and Homer.
Meanwhile cooler temperatures and northerly winds keep Anchorage
and points north just below freezing; although, that too will
change with the next front. Across Southwest Alaska, northerly
winds continue so the warm up is not occurring there quite as
fast. Colder air with the deep upper level trough remains over the
Bering, and widespread stratus clouds are periodically producing
rain showers as temperatures largely hold in the 30s.

Gale force winds moved into the north Gulf coast with the latest
front overnight, but another stronger front is quickly pushing
northward across the southern Gulf this morning. The low south of
Sand point is spreading gusty northerly winds and rain showers
across the eastern Aleutians and Alaska Peninsula.

&&

.MODEL DISCUSSION...

The models are finally coming into better agreement on the
evolution of the pair of lows tracking from the north Pacific into
the eastern Bering. A secondary low has recently formed along the
triple point to the east of the occluding one south of Sand
Point. The secondary low will absorb the first one, thus becoming
the primary. It tracks northwestward across the southern Alaska
Peninsula into the eastern Bering by this afternoon and evening.
From there it will track to near Nunivak Island Sunday afternoon,
then into the northern Bering. While there still is some timing
differences between models, they're in much better agreement.
Thus, forecast confidence has significantly improved regarding
that system.

Unfortunately the next system has large differences between the
models which leads to large differences in the forecast depending
on which one is chosen. What is in agreement, is a low developing
even further south and east in the Gulf than all previous ones.
The low is forecast to track north and west across the central
Gulf and into the north Gulf Coast, likely to Prince William
Sound. The models are very different as to when the center of the
low reaches the Sound, with differences as much as 24 hours. Thus,
there is high uncertainty, but enough of the models are
suggesting sometime Sunday night into Monday morning. The track as
it stands right now is favorable for snow to fall in Anchorage
early Monday morning, but a lot of detail still needs to be worked
out. Stay tuned.

&&

.AVIATION...
PANC...VFR conditions will persist. Winds will remain out of the
north with some variability especially early this morning. A
front moving up the Inlet late this afternoon and evening will
bring some shower activity to the airport. Warm temperatures
should keep the predominant precipitation type as rain. The
precipitation may mix with or change over to snow if it gets to a
heavy-enough intensity, so brief periods of MVFR conditions are
possible with any stronger showers. Once the front passes, the
winds will flip to the southeasterly direction and remain gusty.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
This very active weather pattern for the Gulf continues as one
gale force front is currently dissipating in Prince William Sound
while a much stronger, storm-hurricane force front is quickly on
it's heels. This front will bring another round of strong winds
and seas in excess of 30 ft over much of the Gulf by this
afternoon. It could possibly even bring brief rounds of high
winds (75 mph or higher) to Kodiak Island or Southern Kachemak Bay
as it intensifies to hurricane force along the North Gulf Coast
this afternoon. At this point the risk of high winds looks to be
very brief and as a result, a warning was not issued, but these
areas should still expect a significant ramp up in winds by early
this afternoon. Confidence remains very good that this front will
bring storm force winds as far east as Prince William Sound this
evening, as well as widespread heavy rain and snow to the Eastern
Kenai (including Turnagain Pass) through today. One major
difference regarding this front from the one that pushed through
yesterday, will be much warmer air, bringing snow levels as high
as 1500-2000 above sea level by this afternoon before falling to
around 500 ft overnight. This system is expected to bring
heightened avalanche danger, including to the Turnagain Pass area,
so recreators are encouraged to check their nearest avalanche
advisory center for the latest information. For the lee side of
the Chugach, precipitation will light (if any) as a result of
strong cross barrier flow, and instead will see temperatures
rising well into the 30s with strong gap winds through Turnagain
Arm and out of the Matanuska Valley for much of this weekend.

There will be no rest for the weary even into late this weekend
as the models are beginning to come to a consensus with the track
of an inverted trough from the Eastern-Central Gulf late Sunday-
Monday. As a result confidence is increasing that widespread
accumulating snowfall will develop from Prince William Sound
northward into the Copper River Basin beginning Sunday evening
before spreading westward into Anchorage and the Matanuska Valley
late Sunday- Monday.

&&

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

A fast moving and strong low will move into Bristol Bay today.
This will bring strong gale force winds with some storm force
gusts near the Alaska/Aleutian Ranges. Enough warm air will
quickly turn any snow to rain across Bristol Bay, but it should
remain snow across the Kuskokwim Delta. Snow will favor the coast,
and with a strong pressure gradient, there may be some brief
reductions as low as a a half mile in snow and blowing snow.
Behind the front, temperatures will rise well above average
tonight through Sunday with many inland locales rising above 40
degrees.

The low will then lift north toward the Bering Strait through
Sunday night. Rain and snow showers behind the low will continue
with the bulk of this precipitation along the coast. Temperatures
will slowly drop back closer to normal as weak cold air advection
filters in from the Bering behind the surface low.

&&

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

A strong gale force low will move into Bristol Bay today, with the
core of strongest winds remaining east of Cold Bay. The low will
then slowly weaken and move north along the southwest coast Sunday
evening. Colder air and north-northwest winds will then encompass
the remainder of the Bering Sea.

&&

.LONG TERM FORECAST (Days 3 through 7)...
This forecast period commences with a low near Saint Lawrence
Island and Norton Sound. This setup will sustain southerly winds
across southwestern Alaska and enable weak warm advection. Monday
will see widespread areas of above freezing temperatures across
Southwest and Southcentral Alaska. By Tuesday, the models are out
of sync with the next low entering the Gulf of Alaska. In a
nutshell, the ECMWF is progging the surface low near Kenai and the
GFS is placing the low 300 NM SE at the same time which would
have wildly different implications for the Southcentral AK. As
time elapses, the the GFS pushes that same low north which would
delay the onset of the QPF in PWS which makes hedging the best
tactic. Later in the long-term pattern, all of the models seem to
converge on two major sensible weather concepts. One, the
thickness values plummet bringing brutally cold air south of the
Alaska Range. Two, the seas near the Western Aleutians will become
very dynamic as another round of cyclogenesis is anticipated.
Given the vagaries of the models, hedged between the WPC guidance
and the previous grid package which resulted in small changes to
the long-term package.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Hurricane: 120 130 131.
         Storm: 119 125 132 136 137 138 139 141 351 352.
         Gale: 127 140 150 160 165 180.

&&

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