Gale Warning 589, NWS Anchorage, AK

913 
FZAK61 PAFC 051238
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
338 AM AKST Thu Nov 5 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.

PKZ399-060200-
338 AM AKST Thu Nov 5 2020
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

Weak troughing persists in the northeastern Gulf. A 1016 mb low 
develops at 59N 147W Thu night, then moves southeast along the 
coast Fri to the eastern Gulf Fri night.

$$

PKZ351-060200-
Gulf of Alaska Offshore North of 57N and West of 144W-
338 AM AKST Thu Nov 5 2020

.TODAY...NW wind 15 to 30 kt. Seas 8 to 12 ft. Rain.
.TONIGHT...W wind 10 to 25 kt. Seas 6 to 11 ft. Rain.
.FRI...W wind 10 to 25 kt. Seas 7 to 11 ft.
.FRI NIGHT...W wind up to 15 kt. Seas 6 to 9 ft.
.SAT...S wind 15 to 30 kt. Seas 8 to 13 ft.
.SUN...SW wind 20 to 35 kt. Seas 13 to 21 ft.
.MON...W wind 25 to 35 kt. Seas 9 to 17 ft.

$$

PKZ352-060200-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
338 AM AKST Thu Nov 5 2020

.TODAY...W wind 20 to 30 kt. Seas 9 to 15 ft.
.TONIGHT...W wind 20 to 30 kt. Seas 9 to 13 ft. Rain.
.FRI...W wind 15 to 30 kt. Seas 10 to 13 ft.
.FRI NIGHT...W wind 20 kt. Seas 9 to 13 ft.
.SAT...S wind 15 to 30 kt. Seas 9 to 17 ft.
.SUN THROUGH MON...W wind 20 to 35 kt. Seas 10 to 18 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
504 AM AKST Wed Nov 4 2020

.ANALYSIS AND UPPER LEVELS...

In the upper levels...the closed low over Southcentral AK is
beginning to shift northeast and fill. Even so, it is still
supporting cold air over Southcentral. The shortwave trough that
has been barreling south through Southwest AK continues to do so
and is currently located over the AKPen and beginning to couple
with the closed low over Southcentral. Out in the Bering, upper
level ridging continues to move slowly east, with its axis
currently in the Central Bering. Meanwhile, a fairly deep closed
low exists over eastern Russia, with an associated 500 MB trough
is just starting push east off the coast. Even though it's still
in Russia, this system is of note because it will be the next big
weather maker for the West Coast later this week.

On the surface... Weak troughing still exists along the
Southcentral coast with high pressure and cold air inland. With
this setup cold air is continuing to push through gaps and passes,
creating gusty winds along the Southcentral coast. In the Bering,
a surface high and ridge are in place, with the ridge in the
Central Bering. This surface high stacks down from the upper level
high quite nicely. Also just entering the Western Bering is a
large front, which is the surface reflection of the upper low and
trough in Eastern Russia. This front is moving slowly east and as
stated previously, will be a big weather producer for the entire
Bering and West Coast as it goes.

&&

.MODEL DISCUSSION...

Models continue to largely perform well in the short term. While
there are some minor discrepancies as usual, but models are
picking up on the significant weather features well. In the
Bering, models are performing well with the large front moving
through. In Southcentral, they are depicting the setup of the next
off shore wind event well. This leads to high forecast confidence
for our entire forecast area for the next few days.

&&

.AVIATION...
PANC...VFR conditions will persist. Light northerly winds will
continue through most of the day. However, gusts out of the north
will redevelop this evening.

&&

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

Quiet and very cold conditions are found across the Anchorage
Bowl and Mat-Su Valley this morning. Further south, a fast moving
shortwave is bringing a quick round of snow to the AKPEN and
southern portions of Kodiak Island. Snow should wrap up there by
later this morning.

Tonight the focus shifts to strong winds for Thompson Pass. A
northerly jet punching in, a cold airmass in the Copper River
Basin, and an increasing pressure gradient along Northern Gulf
Coast (courtesy of a deepening surface low in the eastern Gulf)
set the stage for the wind event tonight into tomorrow morning.
Gusts to 75 mph are expected at the pass, with gusts to around 50
mph into the town of Valdez. Wind chills at Thompson Pass will
approach 35 below zero. In addition to Thompson Pass, gusty winds
are expected for Passage Canal and Resurrection Bay tonight into
tomorrow morning.

As these winds subside on Thursday, attention will shift to a
frontal system moving in from Southwest Alaska. Cloud cover will
increase across all of Southcentral early on Thursday with chances
for snow ramping up quickly late in the day for the Anchorage
Bowl, Kenai Peninsula and Mat-Su Valley. The peak of this event
looks to be from Thursday evening into Friday morning, with a few
inches of accumulation possible across a good portion of the area.

On Friday afternoon/evening this front mostly washes out. A few
lingering flurries or occasional snow showers are expected, but
with little to no additional accumulation.

&&

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

The shortwave trough moving south across the Southwest coast
yesterday reaches the North Pacific today. A few snow showers may
linger along the southern AKPEN today as the wave passes, with
relatively drier conditions elsewhere through tonight. A frontal
system approaches the Southwest Coast early Thursday morning.
Flow will be predominantly southwesterly Thursday and Friday,
bringing warmer air into the region and increasing temperatures.
This will allow precipitation to be mostly light to moderate
rainfall along the coasts. Temperatures will likely remain
below freezing further inland, keeping precipitation for the
Kuskokwim Valley and higher elevations as snow. With a persistent
southwesterly flow, coastal flooding becomes a concern,
especially from Kuskokwim Bay to Hooper Bay. A flood watch has
been issued through Friday morning for these two areas as surges
are expected to be anywhere from 3-5 ft above the Highest
Astronomical Tide (grassline). If this storm stays on the current
track, an upgraded product may be issued.

&&

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

A strong frontal system approaches the Western Aleutians this
morning and tracks easterly across the Bering Sea over the next
couple days, weakening as it approaches the Southwest coast.
Widespread gales band of storm force winds with hurricane force
gusts will move across the Bering through tonight. Gales will
persist until tomorrow, bombarding the Southwest and Aleutian
coasts. Behind the front, flow becomes primarily and persistently
westerly, resulting in high seas across the Bering and increasing
the possibility for greater storm surges along the Southwest coasts.

&&

.MARINE (Days 3 through 5)...

Saturday will be the most active weather day of this period as a
developing low will move into the western Gulf of Alaska with
some storm force winds likely with it. There is a bit of
uncertainty as to the track of this low as it could end up farther
west in Bristol Bay, but that would still bring Gales over most
of the Gulf region.

A Gale-force low should move through the Bering sea from the
southwest Saturday through Sunday. However, there is a bit of
uncertainty with this low and it is uncertain whether it will be
quickly followed by a stronger low on Monday, or end up being a
little slower in moving into the Bering Sea.

&&

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

The long term pattern is a bit uncertain through the weekend with
a low moving from south of the Aleutians to the Western Gulf of
Alaska on Sunday. There is a chance this low will take a more
westerly track into Bristol Bay which would mean warmer weather
for Southcentral Alaska, but the most likely solution looks to be
for the development of a triple point low which becomes the main
low by the time it approaches Kodiak on Sunday. This more likely
solution will bring an increased chance of snow for Southcentral
Alaska.

The Bering Sea will have a low move from the southwest corner of
the Bering to the northern part of it Sunday through Tuesday.
However, there is a high degree of uncertainty with this storm.
This is due to a secondary low that will trail the main low and
the interaction of these lows on Monday and Tuesday will dictate
how this system will work out. One of the the biggest impacts
will be the temperatures in Southwest mainland Alaska as the track
will bring a good push of southwest flow over the region and warm
up the temperatures there. This could bring in a mix of
precipitation types with snow, rain and freezing rain all possible
in the Kuskokwim Delta.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 131.
         COASTAL FLOOD WATCH 155.
MARINE...STORMS: 150, 170, 172-179, 185, 411-414.
         GALES: 119, 127, 128, 130-132, 138, 155, 160, 165,
                171, 180, 181
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BJB
SOUTHCENTRAL ALASKA...BG
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KM
MARINE/LONG TERM...EZ