Gale Warning 104, NWS Anchorage, AK

669 
FZAK61 PAFC 060006
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
306 PM AKST Mon Feb 5 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.

PKZ399-061500-
306 PM AKST Mon Feb 5 2018
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 1000 mb low at 55N 152W moves along the front from the Western 
Gulf and arches along the North Gulf Coast to 57N 137W at 1017 mb 
by Wed afternoon. The trailing front sweeps into Southwestern 
Alaska through Wed afternoon. High pressure builds into the
Western Gulf for Wed afternoon.

$$

PKZ351-061500-
Gulf of Alaska Offshore North of 57N and West of 144W-
306 PM AKST Mon Feb 5 2018

.TONIGHT...SE wind 15 to 30 kt. Seas 8 to 11 ft. Rain.
.TUE...W wind 10 to 25 kt. Seas 10 ft.
.TUE NIGHT...W wind 15 to 30 kt. Seas 9 ft.
.WED...NW wind 10 to 20 kt. Seas 7 ft.
.WED NIGHT...NW wind up to 15 kt. Seas 5 ft.
.THU...S wind up to 10 kt. Seas 3 to 7 ft.
.FRI THROUGH SAT...S wind 15 to 25 kt. Seas 8 to 13 ft.

$$

PKZ352-061500-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
306 PM AKST Mon Feb 5 2018

.TONIGHT...SW wind 15 to 30 kt. Seas 11 ft.
.TUE...W wind 10 to 25 kt. Seas 9 ft.
.TUE NIGHT...W wind 10 to 20 kt. Seas 8 ft.
.WED...NW wind up to 15 kt. Seas 7 ft.
.WED NIGHT...NW wind up to 15 kt. Seas 5 ft.
.THU...SE wind 10 to 25 kt. Seas 4 to 8 ft.
.FRI THROUGH SAT...SW wind 10 to 25 kt. Seas 9 to 14 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
414 PM AKST Sun Feb 4 2018

.ANALYSIS AND UPPER LEVELS...
The large upper ridge over the mainland bought another fairly
clear and cold night across the interior southwest Alaska and
Southcentral. Morning lows ranged from the -30s F over the lower
Kuskokwim Valley, minus single digits to minus teens over the
Anchorage Bowl/Mat Valley, to around -40F of the Copper River
Basin. A fairly diffuse frontal band extending from the eastern
Bering Sea to across the central Gulf of Alaska brought clouds and
warmer temperatures to coastal Southwest Alaska and a little
light snow over Kodiak Island. Fairly tight pressure and thermal
gradients continued gusty outflow winds over the eastern Kenai
Peninsula, Thompson Pass/Keystone Canyon, Valdez Narrows into the
afternoon hours today.

&&

.MODEL DISCUSSION...
The general synoptic pattern is fairly similar between the models
with all showing a pattern change to cloudier and warmer weather
this week. The NAM/ECMWF are overall preferred in the with the
position of surface low moving into the northern Gulf. The GFS
appears to be a little too strong and too far west. For the
western domain, models have minor differences in the low position
as it heads north and skirts the southwest coast, but the general
sensible weather ends up being about the same.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist. There is the
possibility of some patchy fog developing along Knik Arm Monday
morning. If this does happen, it would likely bring IFR ceiling
and visibilities. Although confidence is not high this will occur,
it bears consideration.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Southern Alaska remains under the influence of the dominant
arctic high which has been in place for the last week and a half.
One more really cold night is in store as the pressure gradient
weakens and skies remain clear. On Monday, a warm front will lift
north through the Gulf and reach the North Coast by the afternoon,
spreading rain to Kodiak and all snow for the North Coast. Snow
will spread inland, with accumulations of 3-5" for parts of the
Kenai Peninsula. The front will quickly fall apart as it lifts
inland, but light snow will likely spread into Anchorage and the
southern Copper Basin Monday night into early Tuesday. However,
inland amounts north of the Kenai Peninsula look to much lower
with 1-2" or less. The low weakens and moves east Tuesday evening,
bringing snow to an end as surface high pressure re-establishes
itself.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2...Mon and Tue)...
A potent low is taking shape over the North Pacific and will
bring a fairly dramatic shift in the weather to much of SW AK.
Clear skies tonight will allow for another night rapidly cooling
temperatures. But clouds will be on the increase through the day
Monday with the approaching low. East to southeast flow will also
be on the increase, which will help somewhat warmer air to move
into the area. However, temperatures will remain cold enough to
support all snow as precipitation arrives. Snow should start in
the early afternoon for Bristol Bay and then slide into the
Kuskokwim Valley and Delta by midnight. At this time, it looks
like things will be too warm to support much in the way of blowing
snow or even snow accumulations greater than a couple of inches.
However, by the time we get into early Tuesday morning, the low
center itself moves across the Alaska Peninsula and parallels the
coast. It will recycle some colder air and push it into the coast
with some southwest flow. This could lead to some heavier snow
showers and some blowing snow.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2...Mon and
Tue)...
The pattern will remain quite active across the Bering and the
Alaska Peninsula to start the week. The first low southwest of
Adak will continue to decay as it spins over the Western
Aleutians. Meanwhile, the afore mentioned North Pacific low will
take shape and move fairly quickly into the Eastern Bering.
Between these two systems, an elongated deformation axis will
continue to produce steady rain/snow from Dutch Harbor through the
Western Bering. Expect gale-force easterlies to develop tonight
south of the Alaska Peninsula and then spread into the Eastern
Bering Monday morning. With some modest pressure rises behind the
system, gusty southwest winds will develop through the Eastern
Aleutians/AK Peninsula Monday evening into Tue. As this low
drifts northwest and weakens, a new low will bring another round
of rain and small-craft level winds to the Central Aleutians
Tuesday.

&&

.LONG TERM FORECAST (Tuesday evening through Sunday night)...
Our extended forecast begins mid-week with a weak low pressure and
front in the Gulf, bringing snow to the north gulf coast, and
exiting to the east. For interior locations this means clouds and
possibly some very light snow, followed by clear and cold for late
week. Out west, the next active feature of the pattern is a
longwave trough, weakening and broadening over Kamchatka. Both it
and the blocking ridge are decaying from their current state. A
frontal boundary and deep southerly flow will exist across the
Bering Sea.

Into the longer term forecast, guidance quickly devolves into a
jumbled mess. As the two previous anchors in the longwave pattern,
the blocking high and Kamchatka trough, break down, guidance
struggles with a very active east Asian jet, and where exactly to
direct that energy. The big differences in the deterministic
models have to do with how they handle the blocking high pressure.
The ECMWF re-establishes it over the Bering Strait region, keeping
Southcentral AK in a cold outflow pattern, while the GFS wants to
build in a ridge from the sub-tropics getting us into a chinook
pattern. Literally opposites. The extended guidance from WPC will
utilize an ensemble blend for the forecast.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning 127 131 138 150 155 160 165 170 172 180.
 Heavy Freezing Spray 127 160 180.

&&

SYNOPSIS AND MODEL DISCUSSION...RC
SOUTHCENTRAL ALASKA...JA
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MSO
LONG TERM...ML