Gale Warning 489, NWS Anchorage, AK

306 
FZAK62 PAFC 172338
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
338 PM AKDT Sat Sep 17 2022

Offshore Waters Forecast for the Bering Sea

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.

PKZ499-181315-
338 PM AKDT Sat Sep 17 2022
.SYNOPSIS FOR CENTRAL BERING SEA...

A 970 mb near the Seward Peninsula continues moving north into the
Chukchi Sea through tonight. A 1016 mb low forms at 50N 167W Sat 
night and moves into Bristol Bay at 1008 mb through Mon morning. 

$$

PKZ411-181315-
Bering Sea Offshore West of 180 and East of the International
Dateline-
338 PM AKDT Sat Sep 17 2022

.TONIGHT...W wind 10 to 25 kt. Seas 7 to 11 ft. Isolated 
thunderstorms before midnight.
.SUN...W wind 10 to 20 kt. Seas 7 ft.
.SUN NIGHT...NW wind 10 to 20 kt. Seas 7 ft.
.MON...NW wind 10 to 20 kt. Seas 4 to 7 ft.
.MON NIGHT...W wind up to 15 kt. Seas 3 to 6 ft.
.TUE...S wind 20 to 35 kt. Seas 7 to 12 ft.
.WED THROUGH THU...W wind 15 to 25 kt. Seas 11 to 19 ft.

$$

PKZ412-181315-
Bering Sea Offshore 171W to 180 and North of 56N-
338 PM AKDT Sat Sep 17 2022

.TONIGHT...SW wind 20 to 30 kt becoming 10 to 20 kt after midnight. 
Seas 9 to 16 ft.
.SUN...SW wind 15 kt. Seas 7 to 10 ft.
.SUN NIGHT...SW wind 15 kt. Seas 6 ft.
.MON...W wind 10 to 20 kt. Seas 5 ft.
.MON NIGHT...NW wind 15 kt. Seas 5 ft.
.TUE THROUGH THU...W wind 15 to 30 kt. Seas 4 to 9 ft.

$$

PKZ413-181315-
Bering Sea Offshore 171W to 180 and South of 56N-
338 PM AKDT Sat Sep 17 2022

.TONIGHT...SW wind 10 to 15 kt. Seas 7 to 12 ft.
.SUN...W wind 10 to 15 kt. Seas 7 ft.
.SUN NIGHT...W wind 10 to 15 kt. Seas 6 ft.
.MON...W wind 10 to 20 kt. Seas 6 ft.
.MON NIGHT...NW wind 10 to 20 kt. Seas 6 ft.
.TUE...SW wind 10 to 25 kt. Seas 5 ft.
.WED THROUGH THU...W wind 15 to 25 kt. Seas 9 to 14 ft.

$$

PKZ414-181315-
Bering Sea Offshore East of 171W-
338 PM AKDT Sat Sep 17 2022

.TONIGHT...SW wind 20 to 30 kt becoming 15 to 20 kt after midnight. 
Seas 9 to 14 ft.
.SUN...SW wind 10 to 15 kt. Seas 7 ft.
.SUN NIGHT...W wind 10 kt. Seas 5 ft.
.MON...SW wind 15 kt. Seas 5 ft.
.MON NIGHT...SW wind up to 15 kt. Seas 4 ft.
.TUE...W wind 10 kt. Seas 4 ft.
.WED...S wind 15 to 25 kt. Seas 5 ft.
.THU...W wind 20 kt. Seas 4 to 7 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
456 PM AKDT Fri Sep 16 2022

.ANALYSIS AND UPPER LEVELS...

A powerful hurricane force low continues to make its way northward
across the Bering Sea, bringing widespread impacts to across the
Bering Sea, western Alaska coastal waters and onshore into
western Alaska. The low bottomed out at 937mb around 4am this
morning about 275 miles west of St. Paul Island, and is now
beginning to very slowly weaken as it tracks northeastward across
the northern Bering Sea. The strongest winds and highest seas were
observed south and east of the low center across the central
Bering Sea. Bouy 46035 recorded a gust of 66kts/76mph and
significant waveheights of 52 ft during the late morning hours.
Meanwhile, St. Paul Airport observed a wind gust of 64kts/74mph at
124pm this afternoon. The core of strongest winds and waves are
passing north of St. Paul Island and west of Nunivak Island.

While not as strong as in the core, a much larger area of very
strong southwesterly winds is driving across the central to
eastern Bering Sea and toward western Alaska. In addition to wind,
the one big concern for the Kuskokwim Delta region is storm surge
flooding, inundation, and erosion - especially with the high tide
tonight. Concerns for high water levels extend from the Kuskokwim
Bay up the lower Kuskokwim River.

Back behind the low, winds along the Aleutians and southern Bering
Sea have diminished from their peak last night/this morning.
However, winds remain quite gusty along the central to western
Aleutians. An unstable airmass has moved in, leading to remarkably
clear and sunny conditions along the entire Aleutian Island chain.

Looking out ahead of the storm, a frontal system extends from the
northern Bering Sea southeastward across western Alaska, then
southward along the Alaska and Aleutian Ranges. With much of the
upper level forcing continuing northward with the low center,
the frontal system is elongating and weakening as it continues
eastward. As a result, rainfall is quite light and confined to
a fairly small area along and near the frontal boundaries.
Southeasterly gap winds are picking up this afternoon across
Southcentral in response to the approaching front.

&&

.MODEL DISCUSSION...

Overall confidence remains high with the major storm system in the
Bering Sea, with just some fine-tuning of the associated warnings,
advisories, and forecasts. Confidence is also fairly high with
the initial development of an atmospheric river Sunday night, with
rain overspreading much of Southern Alaska. Model spread quickly
develops Monday night/Tuesday and into the extended forecast
period with eastward progression of the atmospheric river, which
pose a threat for heavy rain and flooding next week in
Southcentral.

&&

.AVIATION...
PANC...Shallow southeast flow should be enough to maintain low end
VFR conditions as a frontal system approaches from the west
tonight. However, as the front pushes through early Saturday
(between 12z and 15Z) low level flow will veer around to S to SW,
likely leading to MVFR ceilings. With little change in the flow
during the morning hours, these lower ceilings could hold through
midday. Eventually expect some improvement as upper flow becomes
more westerly and the sun works on eroding some of the lower
level cloud cover.

As for surface winds, expect strengthening gusty southeasterly
Turnagain winds this afternoon and evening ahead of the
approaching front, with some influence from the low in the
northern Bering Sea as well. Winds will diminish a bit early
Saturday as the front moves through. However, synoptic pressure
gradients and more unstable air behind the front will cause
southerly winds coming up Cook Inlet to strengthen Saturday
afternoon.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Tonight through Sunday night)...

Southcentral continues to see increased cloud cover this evening
associated with the passage of a weak warm front. Satellite
imagery shows this cloud cover gradually expanding eastward into
the Copper River Basin and scattered showers are noted on radar
across the Susitna Valley as well as across portions of Prince
William Sound. Very few changes are anticipated in the short term
across Southcentral. Southeasterly Turnagain Arm winds will
eventually increase through the overnight hours, with 15 to 25 mph
winds gusting up to 30 mph possible across south Anchorage, but
more likely on Saturday. As expected, with such a strong low
moving into mainland Alaska, up-inlet flow will likely persist
through much of tomorrow.

One final round of precipitation will be possible early Saturday
morning across Southcentral with the passage of a smaller wave of
low pressure. Thereafter, a much drier air mass will move into
Southcentral, leaving the region dry and clearer from late
Saturday morning into Saturday night. One potential consequence of
the clearer conditions will be stronger radiational cooling
Saturday night. This will allow for at or below freezing
temperatures to develop early Sunday morning across much of the
Copper River Basin with the east side of Anchorage potentially
joining in on the colder weather. The one fly in the ointment for
developing freezing temperatures across Anchorage will be
lingering winds, which may hamper some of this cooling.
Regardless, it would be prudent to make sure any susceptible
plants are covered or brought inside just to be safe.

Sunday also has the potential to be mostly dry although cloud
cover will likely move into Southcentral over the latter half of
the day. Precipitation chances return to the region Sunday night
into early next week as it looks like another atmospheric river
could be directed into Southcentral. Thus, the break from rain
over the weekend will only be temporary.

&&

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

The forecast continues to be on track as expected. The low center
appears to have tracked just very slight east this afternoon than
some models suggested. Gusts between 75 and 85 mph are still
expected along the coast to the west of the mouth of the Kuskokwim
River. Damaging winds could make into Bethel, with sustained
winds of around 40 to 45 kts. Gusts up to 65 kts are possible, but
higher wind speeds aloft could mix to the surface where a gust to
70 mph cannot be ruled out. Winds speeds are expected to peak
sometime around or shortly after midnight and could last for
several hours. Winds should noticeably begin to decrease Saturday
morning and continue to gradually diminish throughout the day.

The Coastal Flood Warning also remains in effect through 4pm
Saturday with surge/tide expected to be 5 to 8 ft above the normal
highest tide line. It remains a possibility that surge will make
it through the mouth of the river and into the Bethel area.
Widespread shower activity is expected along with high winds,
which will decrease visibility. A Flood Advisory has been issued
through Sunday morning. for the potential of minor to moderate
flooding and erosion is likely.

Winds will still be breezy throughout the Bristol Bay and
interior areas with localized stronger winds near the coast and
over some of the higher elevations in the interior. High surf
remains a possibility for the northern Bristol Bay Coast from Cape
Constantine west. Otherwise, these regions should be relatively
calmer, with moderate south to southwesterly winds and rain
showers.

The remnants of Merbok should continue north towards the Bering
Strait Saturday afternoon and the weather should gradually return
closer to normal for Sunday and Monday. A low developing south of
Kodiak Island could bring some southeasterly winds through
Kamishak Gap Sunday night through Monday morning. This system
could bring another round of precipitation across the Bristol Bay
and interior areas Sunday afternoon through Monday.

&&

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

Extratropical storm Merbok is currently located near St Matthew
Island this afternoon. Winds appear to have peaked in St Paul,
however, winds are not expected to really decrease for another few
more hours. The High Wind Warning for the Pribilofs is expected
to end on time at 9PM local. Observed peak winds so far in St Paul
reached 74 mph. Buoy 35 to the west peaked at 78 mph with a peak
recorded wave height of 52 feet. The forecast continues to be on
track with the center very slightly to the east. Overall, the
storm is expected to continue north towards the Bering Strait.
Winds could maintain hurricane force strength as it reaches the
Nunivak Island area, the western Alaska coast, and east St Matthew
tonight, but should be down to storm force by about midnight.
Winds will noticeably decrease by Saturday morning for the
northern Bering, and continue to gradually decrease throughout the
day.

Relatively calmer conditions is expected for Sunday and Monday
although a broad trough will continue to linger over the entire
Bering Sea. Another system will begin to develop just south of the
Alaska Peninsula, bringing more rain through the Peninsula
beginning Sunday and southerly winds to around 20 to 25 kts
following behind and lasting through Monday.

&&

.MARINE (Days 3 through 5: Monday through Wednesday)...

Aleutians / Bering: An elongated area of low pressure across the
Bering moves into Western Alaska by Wednesday. Forecast confidence
is fair with the timing of movement. A front moves from the
Central Bering into the Gulf of Alaska by Wednesday. Generally
light winds over the Bering give way to a new system with gusty
southerly winds increasing to gales over the western Bering
Tuesday, and the Central Bering for Wednesday. Seas building to
20 feet over the Western Bering Wednesday.

Gulf of Alaska: A front enters the Gulf late Monday, and extends
across the Northern Gulf by Wednesday. Gusty Southerly winds ahead
of the front diminish late Monday, then increase as a new North
Pacific low brings widespread gales over the Central Gulf Tuesday.
These gales become a boundary jet along the North Gulf Coast for
Wednesday. Seas to 12 feet over the Northern Gulf and to 16 feet
to the East of Kodiak Island for Wednesday.

&&

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

Unsettled conditions are expected to continue through the
extended period with two more systems impacting Southern Alaska.
The beginning of the long term period begins with a strong upper
level ridge remaining in place across Western North America while
a deep trough remains entrenched over western Alaska. To the west
of this trough, another upper level ridge is present over the
western Bering/Western Aleutians. In between the upper level ridge
and ahead of the upper level trough will be deep, moist, and
southerly flow (AR- Atmospheric River) aimed right into
Southcentral. Multiple upper level shortwaves will move northward
towards Southcentral ahead of this upper level trough. While the
overall pattern is fairly high confidence, the details remain low
to moderate confidence. The reason being the EC and Canadian-NH
remain more progressive with the upper level pattern for Tuesday
and keep the trough more positively tilted to neutral before going
negatively tilted heading into Wednesday. The GFS on the other
hand, makes the upper trough go more negatively tilted earlier on
Tuesday afternoon as well as bringing up much stronger upper level
energy. Though, at this time, this solution appears to be the
outlier. With that said, either way, expect another prolonged
heavy rainfall event across Southcentral with the details
remaining highly uncertain at this time, especially in regards to
amounts. Recommend checking back for updates over the weekend as
the situation continues to evolve and models converge on the
correct solution.

For the remainder of the period, the upper level ridge over the
western Bering/Western Aleutians is expected to be broken down as
another potent storm system moves into the Bering Sea and Southern
Alaska with details (strength, intensity, and track) uncertain at
this point in time. This is important as it would affect where
the main impacts would be felt. Overall, this system will
basically reinforce the whole longwave trough keeping the region
in this very active and wet pattern through the end of next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning: 155, 195.
         Coastal Flood Warning: 155.

MARINE...Gale Warning: 160, 165, 170, 175, 411.
         Storm Warning: 179-181, 413.
         Hurricane Force Wind Warning: 185, 412, 414.

FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...SB
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...VR
MARINE/LONG TERM...MK/MV