Gale Warning 635, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 PM AKST Sat Nov 11 2023

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

An upper-level low continues to drift further into the Gulf of
Alaska this evening with an upper-level ridge tracking into the
region behind it. The aforementioned ridge will build over the
area tonight into Sunday and should bring temporary clearing to
much of the area. This will result in overnight lows dropping for
tonight. Areas across the Copper River Basin will see single
digits, with inland areas for the remaining portions of
Southcentral sitting in the teens, and coastal locations on the
western portion of the Kenai Peninsula, Kodiak Island, and Prince
William Sound areas ranging in the low 20s to 30s.

Attention quickly turns to the next weather maker that moves into
Southcentral from west-to-east Sunday evening through Monday
evening. The nature of this system is different than the previous
ones that brought snow to the area, and is expected to move
through the region fairly quickly and not linger like the others.
However, high snowfall rates are likely with this system as a lot
of moisture is being brought into Southcentral. The question still
remains on what exactly the winds through Turnagain Arm will do.
The current thinking is that winds will increase through the arm
Monday morning, but should stay out of Anchorage proper. However,
if these winds do come into Anchorage proper, then blowing snow is
possible across the Anchorage area. A convergence zone is likely
to form as a result of these winds, and will likely bring higher
amounts in west Anchorage and on the Anchorage and Eagle River
Hillsides, including Hiland Road. Be sure to check back with the
forecast as we continue to monitor this system and refine the
details.

-Sprinkles

&&

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

Unsettled conditions are forecast across the Aleutians and the
Bering the next couple of days. Height rises on the backside of a
Gulf of Alaska trough are contributing to an enhanced pressure
gradient positioned over the Alaska Peninsula in the short term.
Northerly gales with gusts to 55 knots out of bays and passes will
remain possible through the evening hours from Chignik to Akhiok.
A ridge of high pressure over the Bering continues eastward
tonight, which will allow elevated winds over the Alaska Peninsula
to come to an end by or before midnight. Further west, a
Kamchatka low is pushing the next big frontal system into the
Western Aleutians this evening. Ongoing southerly gales ahead of
the front will transition to westerly behind the front later on
Sunday.

The front brings unsettled weather into Southwest Alaska
beginning tomorrow. Strong warm air advection associated with the
front moves inland of the Kuskokwim Coast through the morning
hours on Sunday. With the warmer temperatures a transition from
snow to freezing rain, to all rain is forecast. Light freezing
rain will be possible for locations from Bethel to Dillingham and
on into New Stuyahok. Ice accumulations of a trace to a few
hundredths of an inch may be possible, but should be limited or
tempered by a rather quick warm-up to above freezing. A winter
weather advisory is in effect for the Lower Kuskokwim Valley.
Here, freezing rain with ice accumulations of a trace up to a
tenth of an inch is forecast from Aniak, southward, with light
snow accumulations of 1 to 2 inches. Meanwhile, 4 to 8 inches of
snow is forecast from Sleetmute to Sparrevohn and points
eastward. Snow amounts in excess of 8 inches will be possible at
higher elevations.

The Kamchatka low brings a cold air mass back into Southwest
Sunday night, with temperatures dropping to below freezing just as
quickly as they warmed earlier in the day. This will see any
remaining rain/freezing rain transition back to all snow.

BL

&&

.LONG TERM FORECAST (Days 4 through 7)...

A very progressive weather pattern will continue into and through
the extended range forecast period with multiple strong
shortwaves riding over a strong but broad ridge over the Northern
Pacific. Measures of predictability are good through Friday of
next week and very reasonable clustering of ensemble solutions.
The broad longwave ridge moves across the Southern Mainland
through Thursday. A well developed shortwave trough approaches
Bristol Bay for Wednesday and moves across the Gulf of Alaska
through Thursday. Gale force winds and locally heavy precipitation
will occur from Western Alaska and the Alaska Peninsula. Will
continue to monitor the potential for high surf, coastal flooding
and strong winds from Nunivak Island southward to Bristol Bay.
Gales will continue around Kodiak Island and over the Southern end
of the Kenai Peninsula through Wednesday. Areas of heavy snow for
the Alaska Range and parts of the Kuskokwim Valley. Widespread
precipitation is expected from the Eastern Kenai Peninsula across
the Southcentral Coast to the Canadian border through Thursday.
Expect below normal temperatures to make a return to mainland
Alaska including Southcentral beginning Friday of next week.

CC

&&

.AVIATION...

PANC...

VFR ceilings and visibility and a prevailing light northerly wind
are expected through Sunday morning. There is a chance for some
shallow or patchy fog to develop overnight if skies remain mostly
clear. The next system rolls in Sunday afternoon with ceilings
and visibility becoming MVFR by Sunday afternoon/evening and IFR
Sunday night. This next storm will bring another round of heavy
snow Sunday night through Monday. During periods of heaviest snow,
12z to 18z Monday morning, snowfall rates of an inch per hour are
likely. Rain or freezing rain is NOT expected with this next
system. Winds will increase from the east Monday morning with a
brief period of 25 mph gusts potentially producing blowing snow.

CC/PP

&&