Gale Warning 372, NWS Anchorage, AK

492 
FZAK61 PAFC 062320
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
320 PM AKDT Tue Aug 6 2019

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.

PKZ399-071245-
320 PM AKDT Tue Aug 6 2019
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...
High pressure remains over the Gulf through Thu afternoon. A
frontal boundary extending from the northwest Gulf coast
southeastward through the Barren Islands will impact the area 
through Thu morning.

$$

PKZ351-071245-
Gulf of Alaska Offshore North of 57N and West of 144W-
320 PM AKDT Tue Aug 6 2019

.TONIGHT...NW wind 15 to 30 kt. Seas 7 to 11 ft.
.WED...NW wind 15 to 30 kt. Seas 5 to 9 ft.
.WED NIGHT...NW wind 10 to 25 kt. Seas 5 to 8 ft.
.THU...N wind 10 to 20 kt. Seas 5 ft.
.THU NIGHT...N wind up to 15 kt. Seas 4 ft.
.FRI THROUGH SUN...SW wind 10 kt. Seas 4 ft.

$$

PKZ352-071245-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
320 PM AKDT Tue Aug 6 2019

.TONIGHT...NW wind 15 to 25 kt. Seas 8 ft.
.WED...NW wind 25 kt becoming 15 to 30 kt in the afternoon. 
Seas 6 to 9 ft.
.WED NIGHT...NW wind 15 to 25 kt. Seas 8 ft.
.THU...NW wind 10 to 20 kt. Seas 6 ft.
.THU NIGHT...N wind 10 to 20 kt. Seas 5 ft.
.FRI THROUGH SUN...W wind 10 kt. Seas 4 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
423 PM AKDT Mon Aug 5 2019

.ANALYSIS AND UPPER LEVELS...

A vertically stacked low in the western Bering and a ridge south
of Kodiak continue to steer a plume of moisture from the central
Aleutians northeast over the Kuskokwim Delta. Although rain is
still falling from Dutch Harbor to Bethel and Aniak, rainfall
rates are significantly less than that of this past weekend. Gusty
southwesterly winds along the eastern Bering and west coast of
Alaska are also winding down, with most locations reporting gusts
around 20 to 25 mph. Cold Bay and Cape Newenham remain the
exceptions this afternoon with persistent gusts of 30 to 40 mph.
Westerly small-craft advisory winds are also occurring across the
Barren Islands due to a strong offshore flow.

A weak shortwave is moving east across the southern half of the
state. This is in response to a general westerly flow between the
ridge to the south and a broad trough over the northern Alaska
Coast. This system is producing clouds over Southcentral Alaska
this afternoon along with isolated showers, mainly over the
Talkeetnas and higher elevations of the Copper River Basin. Areas
of low stratus and patchy fog linger across the northern Gulf
Coast and Prince William Sound.

&&

.MODEL DISCUSSION...

Models remain in good agreement with the evolution of the synoptic
pattern and the development of offshore winds across Southcentral
through the short term. Thus, forecast confidence is above
average.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist.

&&

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

As the large upper level ridge centered over the southwestern
Gulf begins shifting to the southeast tonight and then
retrograding and amplifying over Southwest Alaska Tuesday and
Wednesday, the persistent southwesterly flow over the western Gulf
and through Shelikof Strait and Cook Inlet will turn
progressively more westerly and then northwesterly. Winds near the
Barren Islands will remain at or near gale force through midweek
with terrain orientation favoring the westerly component to the
winds. A lee side trough forming along the northern Gulf coast
Tuesday night and Wednesday will additionally help strengthen the
developing offshore flow.

A short wave trough and associated rather wet frontal system in
interior Alaska will track over the top of the the upper ridge
this evening through tonight. While the Alaska range will block
the bulk of the moisture from this system, clouds and areas of
precipitation will spread across the Susitna Valley and into the
Copper River Basin with the potential for a few isolated wet
thunderstorms over the higher terrain. Shower coverage will be
more scattered on Tuesday then taper off quickly Tuesday night as
offshore gradient increases. The drier, north to northwesterly
offshore flow will persist through Wednesday and Thursday with the
downsloping effects and sunnier skies keeping temperatures on the
warmer side despite the air moving in from a cooler source region.

&&

.FIRE WEATHER...

Northwesterly general winds will increase Tuesday night into
Wednesday with favorable orientation of terrain gaps further
enhancing and steering local winds. North to northeasterly winds
increase through Broad Pass in the northern Susitna Valley with
winds more out of the northwest in the Copper River Basin. Gap
winds through the mountains near the Gulf will likely be the
strongest and the driest as they will be further enhanced by a
lee-side trough stretching from Prince William Sound to the east
into the northern Gulf. Expect north winds from Moose Pass
through Seward and into Resurrection Bay, west winds through
Whitter and into Passage Canal and north to northeast winds
through Thompson Pass and down into the Valdez area. Areas along
the Kenai Peninsula will likely see the lowest RHs with them
dropping into the 30 to 35 percent range both Wednesday and
Thursday in locations influenced by the downsloping winds.

&&

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

An area of high pressure currently centered over the Gulf of
Alaska will move to the northwest allowing for the stream of
moisture over Southwest to taper off by Tuesday afternoon. Showers
are expected to continue along the Kuskokwim Delta coast as
several waves propagate from west to east on the north side of the
ridge. Onshore flow is expected to continue, which will allow for
fog development, especially along the coast. Although
precipitation is expected to diminish, cloud cover will persist
through midweek with low level stratus remaining trapped beneath
the ridge. The main forecast challenge over Southwest for the next
few days will be fog.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...

An area of low pressure centered over the western Bering continues
to bring southerly flow across the Aleutians this evening. Expect
showers and southerly flow to continue over the western Bering as
the low lifts northward through Wednesday. Meanwhile, gusty
southerly winds over the eastern Aleutians and Alaska Peninsula will
eventually taper off overnight tonight as a ridge of high pressure
moves over the eastern Bering for Tuesday. Low level stratus and fog
are expected to persist over the eastern Bering through midweek.
Another low pressure approaches the western Aleutians by Thursday
afternoon.

&&

.MARINE (Days 3 through 5)...

Wednesday night starts off with high pressure centered over the
eastern Aleutians and Bering. Northwesterly and offshore flow will
remain over the Gulf and diminishes as the weekend approaches.
Small craft winds are likely near the Barren Islands Wednesday
through Friday until the high pressure weakens and shifts westward
towards the Bering Sea. After this, general low pressure spreads
across the Gulf by Friday. Over the Bering Sea, southerly flow
will continue throughout the forecast period. This persistent flow
will strengthen on Friday over the western Aleutians and Bering
Sea as a front associated with a Kamchatka low approaches. There
is model uncertainty with the strength of this low as it
progresses eastward, but winds are expected to stay small craft
advisory or lower.

&&

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

The ridge of high pressure will be the key feature to focus on in
the extended forecast. Models are in good agreement that the
flattened ridge that has allowed rain into southwest Alaska early in
the week will become more amplified heading into Wednesday night. As
the high pressure continues to build over southwest Alaska on
Thursday, northerly flow will persist over the southwest mainland
and south central Alaska. This will cause much of southern Alaska to
see a warming and drying trend through the end of the week, which
could even bring an increased chance of convection to south central
Alaska. The central and western Aleutians will be on the west side
of this ridge, allowing persistent southerly flow and continued cool
and damp conditions.

Towards the late weekend, this ridge will begin to weaken and
shift to the southwest, keeping the ridge axis stretched across
south central Alaska. Moving into early next week, the models are
a bit uncertain of the ridge breaking down as low pressure moves
into the western Bering Sea. A complex low will develop by Monday
over the western Bering Sea, but the location of its individual
low centers and fronts will be key to how far east the rain will
move.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 130 131.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...TM
SOUTHCENTRAL ALASKA...JR
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KO
MARINE/LONG TERM...AH