Gale Warning 463, NWS Anchorage, AK

873 
FZAK61 PAFC 302219
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
Issued by National Weather Service Juneau AK
219 PM AKDT Wed Sep 30 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.

PKZ399-011230-
219 PM AKDT Wed Sep 30 2020
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 975 mb low offshore of Chignik crosses the Alaska Peninsula into
Bristol Bay Wed evening and weakens as it reaches Nunivak Island
Thu. A new low deepens to 968 mb as it approaches Kodiak Island 
from the S Thu night and reaches Dillingham Fri. 

$$

PKZ351-011230-
Gulf of Alaska Offshore North of 57N and West of 144W-
219 PM AKDT Wed Sep 30 2020

...STORM WARNING THURSDAY NIGHT...

.TONIGHT...S wind 20 to 35 kt. Seas 17 to 21 ft.
.THU...SE wind 20 to 30 kt becoming E 25 to 40 kt in the
afternoon. Seas 13 to 16 ft.
.THU NIGHT...E wind 40 to 55 kt. Seas 15 to 23 ft. Rain.
.FRI...S wind 30 to 45 kt. Seas 20 to 30 ft.
.FRI NIGHT...S wind 15 to 30 kt. Seas 17 to 23 ft.
.SAT...S wind 20 to 30 kt. Seas 12 to 17 ft.
.SUN...SW wind 30 to 45 kt. Seas 17 to 29 ft.
.MON...SW wind 20 to 30 kt. Seas 12 to 20 ft.

$$

PKZ352-011230-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
219 PM AKDT Wed Sep 30 2020

...STORM WARNING THURSDAY AND THURSDAY NIGHT...

.TONIGHT...S wind 25 to 40 kt. Seas 16 to 22 ft.
.THU...SE wind 25 to 35 kt becoming E 35 to 50 kt in the
afternoon. Seas 13 to 20 ft. Rain.
.THU NIGHT...SE wind 35 to 50 kt. Seas 17 to 30 ft.
.FRI...S wind 30 to 45 kt. Seas 21 to 32 ft.
.FRI NIGHT...S wind 15 to 30 kt. Seas 15 to 23 ft.
.SAT...S wind 20 to 35 kt. Seas 14 to 17 ft.
.SUN...SW wind 30 to 45 kt. Seas 20 to 28 ft.
.MON...SW wind 20 to 30 kt. Seas 11 to 18 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
457 PM AKDT Tue Sep 29 2020

.ANALYSIS AND UPPER LEVELS...

The low south of Kodiak Island is continuing to intensify as it
moves northward today. The moisture tap from this system is
nearly down to 30N and feeds directly into this system. Satellite
imagery shows a triple point a little south of Kodiak Island. The
strongest winds with this system will be along the warm front
portion of this storm as it crosses Kodiak Island and vicinity
this evening. This is also a set up where a barrier jet will
develop along the southern part of the Kenai Peninsula and that is
the feature that is expected to enhance the winds to hurricane-
force over parts of the marine area near Kodiak this evening
ahead of this front.

Northerly flow is over the Bering Sea with the approaching low
heading for Bristol Bay overnight. A brief break in between
systems has brought a few hours of sunshine to parts of southwest
Alaska today, but this will be short-lived with the new low
approaching.

&&

.MODEL DISCUSSION...
Models are in very good agreement with the strength and track of
the low cutting to the southwest of Kodiak and into Bristol Bay
tonight. The next low in the parade should move through Thursday
night into Friday on a similar, but slightly more northerly track.
Models are in agreement on the main features, but the actual
track and strength are different enough that there may be some
adjustments on the Kodiak and Alaska Peninsula forecasts over the
next few days. Yet another low will move into the Gulf this
weekend, but models are indicating this one will eventually make
it into Prince William Sound. Timing and strength are similar on
the GFS and ECMWF models so there is reasonable confidence in this
solution at this point.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist through Wednesday
afternoon. Gusty Southeast winds are likely to develop Wednesday
evening.

&&

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

Two separate storms from the North Pacific will keep most of
Southcentral and the Gulf of Alaska under hazardous weather
conditions through the next few days. The first complex storm low
is still parked more than 400 miles south of Kodiak Island, but
the frontal zone from the low is lifting heavy moisture and
extensive areas of rain across the Gulf, with more rainfall
spreading over Kodiak Island, Kenai and Prince William Sound this
evening through Wednesday afternoon. Storm and hurricane force
winds will be strongly felt south of Kenai Peninsula and much of
the western Gulf this evening, while gale force winds will pass
right through Cook Inlet tonight and Wednesday along the axis of
the frontal boundary. As soon as the stronger feature of the
frontal boundary passes westward of Shelikof Strait and Cook
Inlet, winds and wave heights will gradually subside Wednesday
morning through Wednesday afternoon. Rainfall, however, will
continue to spread over the coastal region and farther inland as
cloud remnants trek north-northwestward the next couple days.

The next developing storm from the North Pacific will re-introduce
hazardous weather conditions back into the forecast for much of
western Gulf starting Thursday night. This expected system will
generate inclement weather including heavy rainfall, strong winds
and hazardous waves. Although not a quite a lot of rainfall is
expected over inland, but strong gusty winds are a concern near
Gaps and Passes should this next storm shift more northward before
curving northwestward on Friday afternoon. Overall, anticipate a
very wet pattern and hazardous conditions over the Gulf, with only
minimal showers north of Anchorage and over the Copper River Basin
the next several days.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Thursday Night)...

A pair of strong lows following nearly identical paths (one
following the other) will be impacting Southwest Alaska through
the short term. Both lows are expected to be of similar strength,
as the centers of both track northwestward out of the North
Pacific, cross the Alaska Peninsula near Chignik, then track up
the coast of Southwest Alaska.

The first low is already well developed over the North Pacific
south of the Gulf. Its leading front is already approaching the
coast and will be the more impactful aspect of the storm, causing
winds to hurricane force in the waters along the Pacific side of
the Alaska Peninsula this afternoon through the first half of
tonight. As the front lifts northwestward across Southwest Alaska,
the predominately northeasterly flow should reduce (but not
entirely eliminate) the downsloping to the lee of the Aleutian
Range. Thus, most of Southwest Alaska can expect wetting rains
from the front. The strongest winds will be in the typical areas,
primarily through Kamishak Gap and into Lake Iliamna. The front
will rapidly weaken with time Wednesday morning as it pivots to
track more towards the west, so little rain is expected to survive
the downsloping from the Kuskokwim Mountains to reach the
Kuskokwim Delta midday Wednesday.

Another concern of note will be potential for low water along
coastal Bristol Bay tonight. While fortunately the strongest
northeasterly winds of 55 to 65 mph will not correspond well with
the low tide (the tide will be coming in as the strongest winds
are occurring), it may make for water levels dropping several feet
below mean low tide this evening. In addition, the incoming tide
and strong offshore flow will make for very choppy seas in Bristol
Bay tonight.

The center of the first low will cross the Alaska Peninsula
Wednesday evening in a much weakened state, with gusty winds
through Kamishak Gap and into inland Bristol Bay and continuing
upslope rain along the Kuskokwim Mountains being the primary
lingering effects by Thursday. The second low will rapidly
approach the AKPEN Thursday evening, with another round of strong
easterly winds, heavy rain along the coast, particularly along the
south side of the Alaska Peninsula, and favored east facing
slopes of the Kuskokwim Mountains expected. There will be more on
this second low in upcoming discussions. Temperature-wise, both
lows will reinforce the warm air over the area, making for well
above average temperatures, especially with overnight lows.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today
through Thursday Night)...

A strong low moving out of the North Pacific will track up the
coast over the eastern Bering through Thursday, weakening as it
goes. The low will work to bring seasonably cool air southward out
of Siberia and across the central and western Bering. A large, but
weak area of high pressure over the western Bering this morning
will slowly shift south into the North Pacific by Wednesday, with
the low eventually needing to do all the work of bringing cooler
air south across the central Bering by Thursday. This means a
continuation of the current pattern of widespread cumulus over the
area, some of them producing shower activity, but otherwise
remaining a broken cloud field, allowing many areas to get at
least a little sunshine between the clouds the next several days.
Gales to occasionally storm force northerly winds will impact the
southern Alaska Peninsula and eastern Aleutians starting tonight
and slowly diminishing through the day on Wednesday.

&&

.MARINE (Days 3 through 5/Friday through Sunday)...

Bering/Aleutians

A storm system will move northwestward across the AKPEN into the
eastern Bering Sea on Friday. Winds will remain under gale force
over the open water. There is a chance of gale force winds along
Cape Constantine and Cape Newenham due to the localized funneling
of winds. Confidence is low in the exact forecast of these winds
as there are significant differences in solutions with regards to
the placement and strength of the low center. The general trend is
this storm system will move into the northeastern Bering Sea and
weaken while remaining stationary through Sunday.

Gulf of Alaska

A storm system will move northwestward through the western Gulf
and cross the AKPEN into the Bering on Friday. Widespread gale
force south-southeasterly winds associated with this storm system are
expected in the Gulf on Friday. These winds will ease to below
gale force Friday night and on Saturday. However, a second storm
system will move into the southern Gulf on Sunday. Confidence is
very low in the forecast for Sunday as there are significant
discrepancies between solutions on the placement and intensity of
the low center.

&&

.LONG TERM FORECAST (Days 3 through 7/Friday through Tuesday)...

The pattern remains highly amplified as a deep negatively-tilted
upper trough extends across the Bering/Aleutians and the AKPEN
while an upper ridge extends across the west coast of Canada. A
strong storm system will move northwestward from the Gulf of
Alaska into the eastern Bering/Aleutians. This low will
potentially bring 2-3" of rain to Kodiak and the southern Kenai
Peninsula. Widespread gale force winds are expected in the western
Gulf on Friday as this system moves over Kodiak and the AKPEN.
This storm system will move into the northeastern Bering Sea and
weaken into a trough through Sunday. A second storm system will
move into the southern Gulf of Alaska on Sunday, though forecast
confidence with respect to this second system is low as there are
significant differences between solutions in regards to the
placement and intensity of this low. The overall trend is this low
will move into the northern Gulf/southern Alaska mainland and
weaken into a trough while remaining nearly stationary, however
there is a high degree of uncertainty where this will occur due to
the significant model differences. A third storm system will move
into the western Bering/Aleutians Tuesday afternoon, though
confidence is very low as there are significant discrepancies in
solutions with respect to the placement and intensity of this low.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Hurricane force wind warning 131 132 138 150.
Storm warning 119 120 130 136 137 139 155 160 165 170 171 172 351 352.
Gale warning 127 140 180 414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...CB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...ED

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
312 AM AKDT Wed Sep 30 2020

AKZ101-010500-
Anchorage-
Including the cities of Anchorage, Eagle River, Indian,
and Eklutna
312 AM AKDT Wed Sep 30 2020

...STRONG WINDS ACROSS TURNAGAIN ARM AND THE ANCHORAGE BOWL THIS
EVENING THROUGH THURSDAY NIGHT...

A series of storm force lows and fronts head north and bring
bouts of strong winds across the Anchorage Bowl and Turnagain Arm.
The first of these two storms will produce strong easterly winds
with gusts in the 60 to 70 mph range along Turnagain Arm and
higher elevations this evening. Lower elevations will experience
southeast winds of 20 to 45 mph. Winds with this first system
will peak overnight tonight, but will remain fairly gusty through
Thursday. The second storm moving north Thursday night into Friday
will bring another round of strong winds across Turnagain Arm and
higher elevations.

Please check www.weather.gov/anchorage for updates.