Winter Weather Advisory 77, NWS Anchorage, AK

361 
WWAK42 PAFC 301329
WSWALU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
429 AM AKST Thu Dec 30 2021

AKZ155-310200-
/O.CON.PAFC.WW.Y.0077.211230T2100Z-211231T1500Z/
Kuskokwim Delta-
Including the cities of Bethel, Hooper Bay, and Nunivak Island
429 AM AKST Thu Dec 30 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO
6 AM AKST FRIDAY...

* WHAT...Blowing snow expected. Total snow accumulations of 4 to 
  6 inches. Northeast winds 20 to 30 mph with gusts as high as 40 
  mph.

* WHERE...Kuskokwim Delta.

* WHEN...From noon Thursday to 6 AM AKST Friday.

* IMPACTS...Plan on difficult travel conditions. Areas of 
  blowing snow will reduce visibilities to as low as one half 
  mile.

* ADDITIONAL DETAILS...A front will begin to push onshore of the
  Kuskokwim Delta Coast midday Thursday bringing snow and gusty
  winds which are expected to reduce visibility as a result of
  blowing snow. The heaviest snow, and accompanying worst
  visibility, will move from south to north across the Delta
  through Thursday night. Late Thursday night, snowfall rates and
  winds will decrease, leading to improved conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling.

&&

$$

http://www.weather.gov/afc

136 
WWAK42 PAFC 310030
WSWALU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
330 PM AKST Thu Dec 30 2021

AKZ155-311500-
/O.CON.PAFC.WW.Y.0077.000000T0000Z-211231T1500Z/
Kuskokwim Delta-
Including the cities of Bethel, Hooper Bay, and Nunivak Island
330 PM AKST Thu Dec 30 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 6 AM AKST
FRIDAY...

* WHAT...Blowing snow. Additional snow accumulations of 4 to 6
  inches. Northeast winds 25 to 35 mph with gusts as high as 45 
  mph.

* WHERE...Kuskokwim Delta.

* WHEN...From noon Thursday to 6 AM AKST Friday.

* IMPACTS...Plan on difficult travel conditions. Areas of 
  blowing snow will reduce visibilities to as low as one half 
  mile.

* ADDITIONAL DETAILS...A front moving through the Kuskokwim Delta
  is resulting in reduced visibility as a result of blowing snow.
  The heaviest snow, and accompanying worst visibility, will move
  from south to north across the Delta through tonight. With winds
  reaching 35 mph, locations along the coast may see visibility 
  as low as one quarter mile at times. Early Friday morning, 
  snowfall rates and winds will decrease, leading to improved 
  conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling.

&&

$$

http://www.weather.gov/afc

356 
WWAK42 PAFC 311436
WSWALU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
536 AM AKST Fri Dec 31 2021

AKZ155-311545-
/O.EXP.PAFC.WW.Y.0077.000000T0000Z-211231T1500Z/
Kuskokwim Delta-
Including the cities of Bethel, Hooper Bay, and Nunivak Island
536 AM AKST Fri Dec 31 2021

...WINTER WEATHER ADVISORY WILL EXPIRE AT 6 AM AKST EARLY THIS
MORNING...

Snow showers will taper off this morning for the Kuskokwim Delta.
Dry and cold conditions will move into the region.

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
448 AM AKST Wed Dec 29 2021

.ANALYSIS AND UPPER LEVELS...

A ~150 kt jet streak extends from the western Aleutians through
the Kuskokwim Delta and across the northern Gulf. The associated
500 mb ridge is slightly less amplified than yesterday, although
the 540 Dm line still remains north of Bethel, allowing warmer
temperatures to persist over much of the southern half of the
state. A deep fetch of southerly moisture originating from near
30N is seen on current water vapor imagery brining widespread
rain across the entire Aleutian Chain. Quiet conditions are seen
across southwest Alaska under the aforementioned ridge axis, with
some patchy fog and low stratus over the Kuskokwim Delta. Much of
the earlier light precipitation across Southcentral has departed
to the east and gradual clearing from west to east is expected
this morning. Lingering snow is still occurring over the Copper
River Basin, behind a surface low centered near Yakutat.

&&

.MODEL DISCUSSION...

Synoptic model agreement remains good in the short term indicated
quiet conditions across Southcentral under a ridge. Agreement is
also very good for the next system, with all showing snow away
from coast beginning late Thursday evening. As such, confidence is
above average.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist through
Thursday morning.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

The warm air that has been in place over Southcentral is giving
way to some cold advection behind an upper level wave that has
moved through the area and is in the eastern Copper River Basin
early this morning. The cold advection is not a sharp surface
front and is more trickling in from the northwest. Often with such
a pattern where there has been warm air in Southcentral, there is
cold air that moves into the area up Cook Inlet from the
southwest. However, today the pattern is more zonal with the
colder air definitely to the north with an 850 mb temperature
gradient of around -10C in the Susitna Valley to -2C over Kodiak
Island. This temperature gradient will become especially important
to the weather tomorrow into Friday over Kodiak Island and the
Kenai Peninsula with the precipitation type as the next warm front
moves to Kodiak tonight and then as a more complex set-up takes
shape for Friday.

For Kodiak Island, there is some colder air aloft that is expected
to move over the island this afternoon. While it is still well
above freezing at most sea level locations around the island, if
it can drop below freezing this evening before there is a chance
that the could be areas of freezing rain over the island as warmer
air aloft causes rain to fall into the below freezing
temperatures. This is a possibility, especially on the southern
side of the island. Near Kodiak City, it looks more likely that if
it is cold enough for snow with the beginning of the
precipitation, it will be a clean transition to rain without the
freezing rain aspect as temperatures will warm again fairly fast
Thursday morning.

The warm front will have a triple point low develop along it near
the southern coast of the Kenai Peninsula on Friday morning. This
will occur as a much stronger push of cold air moves into
Southcentral from the northwest as an upper level low digs into
the Bristol Bay area. This should keep the P-type as snow for the
Kenai Peninsula and northward for the precipitation Thursday night
into Friday. This is also a set-up that will likely cause the
development of a deformation band somewhere over or near Cook
Inlet which will cause locally heavier snowfall somewhere. A
little too early to get a good lock on where this will be but
hopefully it will become clearer as we get closer.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 2: Today
through Thursday night)...

A pause in the active weather will continue this morning with
calming winds and mild but not quite as unusually warm
temperatures hovering right around the freezing mark. A pair of
systems will impact parts of the region thereafter, with the first
arriving as a weakening front from the eastern Bering by this
afternoon. A band of snow will overspread mainly the southern
portions of Bristol Bay as the front approaches and begins to
stall out, with about 1 inch of new accumulation possible between
Togiak and and King Salmon and south into the northern Alaska
Peninsula before snowfall tapers off later tonight.

Looking into Thursday, a second and more significant snow and
possibly mixed precipitation event should begin to materialize as
a potent low moves into the central Bering. Deep warm advection
ahead of the low will essentially reinvigorate the initial frontal
axis sprawling across the eastern Bering and Alaska Peninsula,
with the front then lifting north into the Southwest coastline by
Thursday afternoon. Light to moderate snowfall will overspread
much of the region from southwest to northeast as the front
advances, with new snowfall totals of 3 to 6 inches possible over
the Y-K Delta and much of Bristol Bay through late Thursday
night. Farther south, some concerns remain for return of a wintry
mix of precipitation, with potential for a weak nose of warm air
aloft to intrude over the cool air mass in place and potentially
allow for a period of snow mixing with freezing rain and sleet.
This is most likely to occur with the initial band of frontal
precip as it crosses over the northern Alaska Peninsula on
Thursday morning before winds behind the front veer from easterly
to southerly and help warm temperatures above freezing at ground
level. There remains some uncertainty as to how far the warmer air
aloft will be able to work north along the front, with a period
of wintry mix not out of the question as far north as Dillingham
and King Salmon during parts of the day on Thursday. Be sure to
check back for forecast updates as the potential for both snowfall
and mixed precipitation become better defined.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 to 2: Today
through Thursday night)...

A frontal system will advance quickly northeast across the eastern
Bering and Aleutians this morning, sending mainly rain and winds
up to gale force across the eastern Aleutians as it moves across.
The front will reach the Pribilofs by about midday today with
winds increasing to gales and a mix of rain and snow moving in
through this afternoon. A much larger scale and more significant
system will take shape heading into tonight and Thursday as a
deepening North Pacific low crosses the western Aleutian Chain
into the Bering. A surge of tropical moisture ahead of this low
should effectively reinforce the existing front still extending
over much of the central and eastern Bering, sending warmer air
north along with mainly rain showers across the Aleutians and up
into the Pribilofs through much of Thursday. Polar air will wrap
around the low as the low matures and shifts into the eastern
Bering, helping to support northwest winds vaulting up to storm
force and seas building to near 30 ft along parts of the western
Aleutians by Thursday afternoon. Meanwhile, northeast winds close
to storm force and cooling temperatures in the northern Bering
will result in the return of areas of heavy freezing spray on
Thursday into Thursday night, mainly for areas close to the
Kuskokwim Delta Coast and near/north of Saint Matthew Island.

&&

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

Bering...A low in the Eastern Bering tracks across the AKPEN
Friday. Winds will be northerly across the Central and Eastern Bering,
peaking at high-end gales on the backside of the low. As the low
exits into the Gulf, storm-force gap winds and heavy freezing
spray are possible south of the AKPEN late Friday through early
Sunday. In the Western Bering, a strong front will bring southerly
gales and areas of storm-force winds Friday through Sunday. Seas
will be mostly 8-15 ft except 15-25 ft where gales are expected.

Gulf of Alaska...Winds increase to widespread small crafts Friday,
with a gale-force barrier jet along the northern Gulf Friday
morning. Gusty outflow winds intensify to gales early Saturday
and persist through Sunday, with storm-force winds likely through
Kamishak Gap. Heavy freezing spray is possible with these strong
and cold outflow winds. Seas 10 ft and lower Friday increase to
15-25 ft Saturday and Sunday.

&&

.LONG TERM FORECAST (Days 4 through 8: Saturday through
Tuesday)...

An upper-level ridge in the Bering moves eastward into Alaska
through Tuesday, transitioning the weather towards cold and mostly
dry conditions. On Saturday, an upper-level trough over Alaska
and a surface low in the Gulf will produce snow over Southcentral
and drive gusty gap winds. As the low moves out of the Gulf
through Saturday, snow will slowly taper off. Cold, northerly gap
winds out of the AKPEN and northern Gulf Coast will continue
through Monday due to high pressure over the interior and ridging
in the Eastern Bering. Cold air advection and clearer skies at
night will allow temperatures to drop below negative during the
weekend.

Behind the upper-level ridge, a strong warm front brings rain and
southerly winds as it tracks across the Aleutians through
Tuesday. Some uncertainty remains with how quickly the front will
move east. However, temperatures warm by Tuesday across Southwest
as the front approaches.

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storm Warning: 176 177.
		 Gale Warning: 119 129 170 172-175 178-181 185 351 411-414.
         Heavy Freezing Spray Warning: 181 185.
FIRE WEATHER...NONE.

&&

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