Storm Warning 102, NWS Anchorage, AK

681 
FZAK61 PAFC 222317
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
317 PM AKDT Sat Oct 22 2022

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.

PKZ399-231345-
317 PM AKDT Sat Oct 22 2022
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 988 mb low near 55N 153W tracks across the southern Gulf on Sun
before moving into SE Alaska Sun night. A 1007 mb low over the 
Alaska Peninsula Mon morning moves to 57N 140W at 1004 mb Mon 
afternoon.

$$

PKZ351-231345-
Gulf of Alaska Offshore North of 57N and West of 144W-
317 PM AKDT Sat Oct 22 2022

...GALE WARNING TONIGHT...

.TONIGHT...NE wind 25 to 40 kt. Seas 8 to 13 ft. Rain.
.SUN...NW wind 20 to 30 kt. Seas 8 to 13 ft. Rain.
.SUN NIGHT...W wind 20 to 30 kt. Seas 9 to 13 ft.
.MON...NW wind 10 to 25 kt. Seas 7 to 10 ft.
.MON NIGHT...NW wind 10 to 25 kt. Seas 7 to 10 ft.
.TUE...SW wind 15 to 30 kt. Seas 6 to 11 ft.
.WED THROUGH THU...NW wind 30 to 45 kt. Seas 13 to 20 ft.

$$

PKZ352-231345-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
317 PM AKDT Sat Oct 22 2022

...GALE WARNING THROUGH SUNDAY...

.TONIGHT...SW wind 25 to 40 kt becoming NW after midnight. Seas 10
to 17 ft. Rain.
.SUN...NW wind 25 to 40 kt becoming 30 kt in the afternoon. Seas
11 to 18 ft. Rain.
.SUN NIGHT...W wind 30 kt. Seas 11 to 15 ft. Rain.
.MON...W wind 20 to 30 kt. Seas 10 to 14 ft.
.MON NIGHT...W wind 15 to 25 kt. Seas 9 to 13 ft.
.TUE...W wind 25 to 40 kt. Seas 9 to 17 ft.
.WED THROUGH THU...NW wind 30 to 45 kt. Seas 16 to 25 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
447 PM AKDT Fri Oct 21 2022

.ANALYSIS AND UPPER LEVELS...

The jet stream continues to stretch near the Aleutians and south
towards the Pacific Northwest. This will keep the storm track near
the Aleutians and into the southern Gulf over the next couple of
days.

Satellite shows a low pressure system southeast of Cordova this is
producing light snow across the Copper River Basin with snow
accumulations up to 2 inches observed. This is also producing a
few showers across eastern Prince William Sound towards Cordova
and Valdez. Fog and stratus observed this morning across northern
Cook Inlet to west Anchorage and the MATSU valleys will slowly
lift and burn off by this afternoon.

Across the southwest a weak shortwave is moving across Bristol Bay
producing a few showers.

Meanwhile a surface with supporting upper level shortwave is
spinning south of the western and central Aleutians bringing
clouds and light rain to parts of the Aleutians today.

Over the Bering, westerly flow continues along with colder
temperatures aloft flowing over the relatively warm water surface
of the Bering. This is resulting in lots of cumulus clouds due to
the unstable atmospheric profile this is creating. Some of these
clouds will grow tall enough to produce showers.

&&

.MODEL DISCUSSION...

Model guidance remains in good agreement with the synoptic scale
features out through Day 3 (Monday). There are some minor
differences on the placement of two low pressure systems moving
across the Bering Sunday and Monday. The impacts of the second low
on Monday into Tuesday are expected to be minimal regardless of
the track as any potential storm surge/ high surf will coincide
with the New Moon so tides will be lower.

&&

.AVIATION...

PANC...VFR conditions expected through tonight, however fog and
stratus may redevelop again towards tomorrow morning with IFR or
lower conditions possible. Light winds are expected to persist
throughout the TAF package.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
3/Tonight through Monday night)...

The last vestiges of snow will come to an end across eastern
portions of the Copper River Basin tonight as a shortwave trough
departs the region into Canada. This will leave the rest of
Southcentral dry through the next few days. Cold air advection
behind the trough will maintain gusty conditions through the gaps
and passes through the evening hours from Seward to Whittier as
air drains into Western Prince William Sound. Gusts ranging from
20 to 30 knots will gradually taper off tonight through early
Saturday morning. Accelerated winds are also spilling out of the
Western Alaska Range into Cook Inlet and the Shelikof Strait. Gust
of 20 to 25 knots will stretch across the Barren Islands with a
core of westerly gales spanning zone 351. These winds too will
gradually diminish through early Saturday as the pressure gradient
eventually relaxes.

The next upper low moves into the western Gulf late Saturday.
Gales are forecast to expand in coverage across the southern and
central Gulf while the low takes a more southerly track through
the region. While the strongest winds will likely remain well
offshore of coastal areas, Kodiak Island could see some northerly
gale force gusts Saturday night. More notable, the isallobaric
wind component of the low is expected to promote northwest to
westerly storm force winds over southern portions of zone 352
early Sunday morning. Corresponding seas may approach 20 feet as a
result.

Otherwise, drier and clearer conditions across Southcentral will
result in cooler nights. Overnight lows for areas inland of the
coast will be in the teens to upper 20's through early next week.
A threat for fog will again develop during the morning hours on
Saturday from the Kenai Peninsula up into the Mat-Su.

&&

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

Expect onshore flow to persist this forecast period. A low from
the North Pacific is moving toward the Alaska Peninsula and
Bristol Bay and will reach the area Saturday morning. This low's
trajectory will keep most of the moisture south of Levelock and
the low is will be south of Kodiak by Saturday evening. Expect a
lull in activity and then a second fast moving low will push
across the Bering. The leading edge of the precipitation shield
will be at Nunivak and Cape Newenham by Sunday evening. The
dynamics are not impressive with this second low but it will bring
light showers into Monday.

&&

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

A large upper level low continues persists over eastern Russia
and the Bering this afternoon. At 500 mb there is an oblong shaped
closed low near Kamchatka and there are multiple shortwaves
propagating around this upper low through zonal flow. On
satellite imagery (CIMSS MIMIC PW) there is a deep fetch of
moisture south of the Aleutians that extends all the way to the
Philippines. Also on satellite imagery (AMSR2) sampled rain rates
are as high as .50 of an inch per hour south of Adak. Dutch Harbor
to the Alaska Peninsula will get heavy rain this weekend.
Additionally, there are a couple of weak surface lows that will
sustain light showers over portions of the Bering. Late Saturday,
a second system will approach the Western Aleutians but the
surface low is only 1004 mb and it doesn't look as organized but
it will bring showers to the chain.

&&

.LONG TERM FORECAST (Days 4 through 7/Tuesday through Friday)...

Transient upper level ridging will extend across Southcentral and
Southwest Alaska on Tuesday. This ridging will be shortly lived as
deep upper level troughing will move over Southcentral and
Southwest Alaska on Wednesday and persist through Friday. The odds
show a moderate to strong tilt in favor of colder than normal
temperatures and a slight to moderate tilt towards above normal
precipitation for the extended period.

During this time, a low pressure system is forecast to move
southeastward from over the Bering Sea, across Southwest Alaska
and into the Gulf of Alaska Tuesday and Wednesday, then exit to
the east on Thursday. The southerly track of this storm with
respect to the Alaskan mainland will help reinforce the cold air
and allow for snow to be the most likely precipitation type across
the area. There is low confidence at this time to the exact
precipitation type for coastal areas at this time. With respect to
those areas, a farther off shore track (farther south) would
increase the probability for snow and a more inland track
(northerly track) would decrease the probability for snow and
increase the probability for rain. The track of this low is also
likely to result in strong winds through the Valdez Narrows on
Wednesday due to strong northeast to southwest pressure gradients.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 131 132 150 155 172 174-178.
FIRE WEATHER...NONE.

&&$$

SYNOPSIS AND MODEL DISCUSSION...RC
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PJS
LONG TERM...ED