Winter Storm Watch 9, NWS Anchorage, AK

038 
WWAK42 PAFC 041351
WSWALU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
451 AM AKST Sat Dec 4 2021

AKZ155-050300-
/O.UPG.PAFC.WS.A.0009.211205T0600Z-211206T1500Z/
/O.NEW.PAFC.WS.W.0004.211205T0600Z-211206T1300Z/
Kuskokwim Delta-
Including the cities of Bethel, Hooper Bay, and Nunivak Island
451 AM AKST Sat Dec 4 2021

...WINTER STORM WARNING IN EFFECT FROM 9 PM THIS EVENING TO 4 AM
AKST MONDAY FOR KUSKOKWIM DELTA...

* WHAT...Heavy snow and blowing snow expected. Total snow
  accumulations of 5 to 10 inches. Winds gusting as high as 55  
  mph.

* WHERE...Kuskokwim Delta.

* WHEN...From 9 PM this evening to 4 AM AKST Monday.

* IMPACTS...Plan on slippery road conditions. Areas of blowing 
  snow could significantly reduce visibility.

* ADDITIONAL DETAILS...As the front passes through the warned
  area, hazardous heavy snow and blowing snow could become
  widespread leading to very low to no visibility. Strongest peak
  winds are expected along the coast which could potentially bring
  water up over shorefast ice, leading to minor coastal flooding,
  particularly along Kuskokwim Bay. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow means severe winter weather
conditions will make travel very hazardous. If you must travel,
keep an extra flashlight, food and water in your vehicle in case
of an emergency. 

&&

$$

AKZ161-050300-
/O.UPG.PAFC.WS.A.0009.211205T0900Z-211206T1800Z/
/O.NEW.PAFC.WS.W.0004.211205T1200Z-211206T1300Z/
Bristol Bay-
Including the cities of King Salmon, Dillingham, Naknek, 
and Pilot Point
451 AM AKST Sat Dec 4 2021

...WINTER STORM WARNING IN EFFECT FROM 3 AM SUNDAY TO 4 AM AKST
MONDAY FOR BRISTOL BAY...

* WHAT...Heavy snow and blowing snow expected. Total snow
  accumulations of 5 to 14 inches, with the highest amounts along
  the coast from Clarks Point to Dillingham to Manokotak. Winds 
  gusting as high as 50 mph.

* WHERE...Bristol Bay.

* WHEN...From 3 AM Sunday to 4 AM AKST Monday.

* IMPACTS...Travel could be very difficult. Areas of blowing 
  snow could significantly reduce visibility.

* ADDITIONAL DETAILS...Snow may mix with or changeover to rain at
  times, mainly for coastal locations. Additionally, the strong
  onshore winds could be strong enough to bring water up over
  shorefast ice, leading to minor coastal flooding, particularly 
  along the northern coastline of Bristol Bay.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow means severe winter weather
conditions will make travel very hazardous. If you must travel,
keep an extra flashlight, food and water in your vehicle in case
of an emergency. 

&&

$$

AKZ152-050300-
/O.UPG.PAFC.WS.A.0009.211205T0900Z-211206T1800Z/
/O.NEW.PAFC.WW.Y.0061.211205T1200Z-211206T1300Z/
Lower Kuskokwim Valley-
Including the cities of Aniak and Sleetmute
451 AM AKST Sat Dec 4 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 AM SUNDAY TO 4 AM
AKST MONDAY FOR THE LOWER KUSKOKWIM VALLEY...

* WHAT...Snow and blowing snow expected. Total snow accumulations
  of 4 to 10 inches. Winds gusting as high as 30 mph.

* WHERE...Lower Kuskokwim Valley.

* WHEN...From 3 AM Sunday to 4 AM AKST Monday.

* IMPACTS...Plan on slippery road conditions. Areas of blowing
  snow could reduce visibilities to under one mile.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

&&

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
557 AM AKST Fri Dec 3 2021

.ANALYSIS AND UPPER LEVELS...

An upper level ridge axis, oriented north-south over the western
portion of the state is moving east, forcing the upper level
trough and northern Gulf low eastward. A front over the Bering
and central Aleutians also continues to move eastward. Gusty
southerly winds are occurring just ahead of the front, with gusty
northwest winds occurring behind. These winds are causing heavy
freezing spray in ice free areas in the Bering where temperatures
are below freezing. While most coastal areas are on the warm side
with temperatures generally in the teens and 20s, temperatures
inland remain quite cold with readings below zero.

&&

.MODEL DISCUSSION...

Model runs have remained quite consistent with placement and
movement of the synoptic features at least through the weekend.
The low over the Gulf will sink southeast out of the picture by
tonight. Meanwhile the strong cold front currently moving across
the Bering will continue to march east before significantly
slowing its progress when it reaches the southwest part of the
state this evening.

By early Saturday, models suggest a couple of surface lows
developing in the lee of the AKPEN, north and south of Kodiak
Island. These lows do not look to strengthen much. However the
next storm system and front moving across the Bering looks to have
a strong upper level jet associated with it, as well as being able
to tap into significant moisture. While the models are in
reasonably good agreement, there are subtle differences which
could make a big difference in realized precipitation amounts.
That being said, confidence is increasing for impactful weather
across most of Southwest and SouthCentral beginning Sunday.

&&

.AVIATION...

PANC...Fog with VLIFR ceiling/vis has formed along Knik Arm.
A light northerly drift could bring this down to the terminal
this morning. Will start to introduce this potential in the TAF,
but this could end up being a long-lived fog event with nothing
in store to help clear it out of the area.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Sunday night)...

As a low exits across the eastern Gulf today, an upper level
short-wave will drop southward across Southcentral. This will
lead to development of meso-scale lows over the northern Gulf
along with snow showers. A few of these showers could push onshore
along the Gulf coast, but expect most of them to remain offshore.
Subsidence with passage of the upper trough could lead to an
uptick in gap winds along the coast, particularly for Valdez and
the Copper River Delta. Gap winds will then gradually diminish
tonight through Saturday, though they won't die down completely
due to persistent colder air and higher pressure sitting inland.

Away from the coast, expect continued bitter cold conditions
through the weekend. There are some areas of clouds, particularly
across the Copper River Basin, which will serve to moderate
temperatures. Saturday morning still looks like the timing of
coldest temperatures for most areas, under the influence of a
short-wave ridge passing overhead. With progressive flow aloft,
a short-wave trough will then march eastward across the region
Saturday afternoon through early Sunday. While most dry conditions
will prevail, this will usher in some mid to high level clouds
helping to moderate temperatures. Expect a weak low to develop
south of Kodiak as a separate short-wave digs southeastward into
the Pacific. There may be a brief period of light snow on Kodiak
Island Saturday, but the upper wave and low will quickly exit
eastward late Saturday.

As we continue through the weekend, all eyes will turn to a major
storm system crossing the Bering Sea. This will bring widespread
significant winter weather to all of southern Alaska. With
abundant moisture and strong dynamics, this system has high
potential to produce heavy snow across a large portion of the
region. Strong winds and some warm air advection will likely lead
to a change to rain along the immediate coastline, but this is
looking like a mostly snow event. As far as timing, expect
deteriorating conditions across Southcentral, Kodiak, and the
Gulf of Alaska Sunday afternoon through Sunday night. Stay tuned
for detailed impacts from this major winter storm.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Sunday night)...

A resilient front over the eastern Bering will create blizzard
conditions for the Kuskokwim Delta Coast including Chevak and
Hooper Bay this morning. The dynamics of the front and the
targeted warned areas warranted the issuance of a Blizzard
Warning since yesterday afternoon. This episode could potentially
produce 3 to 5 inches of snow accumulation today. As the front
pushes farther inland tonight into Sat afternoon, light to
moderate snow will make its way through much of Southwest as
tropical moisture fills the area starting this morning.

A second front from the Bering poses concerns for heavy snow and
blowing snow for the Southwest this weekend through Sun night, and
this could be our first major storm for the winter. The magnitude
of this storm could create widespread impact for the area, leading
to reduced visibilities and hazardous conditions affecting
lives and properties. Essentially, this latter system should be
closely monitored as it may prompt additional Advisory/Warning.
Overall, cold wintry pattern will continue, with strong gusts
expected along the gaps and passes and in areas where the fronts
passes through.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS/AKPEN (Days 1 through
3: Today through Sunday night)...

Two separate fronts will remained headlined in the forecast over
the weekend, with the first one already making its way toward
Southwest AK this morning. The second front, which could be our
first major storm this winter, will bring active weather across
the Bering/Aleutians including large seas, gales and storm-force
winds the next couple days. All in all, there's a brief break in
between the two fronts, but the general public should closely
monitor the second front this Saturday and Sunday as this latter
system could generate widespread impacts on lives and property.

&&

.MARINE (Days 3 through 5/Sunday through Tuesday)...

Bering/Aleutians...

Forecast confidence is low to moderate on Sunday and then becomes
low for Monday and Tuesday. A large low pressure system is
expected to move across the Bering/Aleutians at this time and
produce widespread gale force winds. However, there are
significant differences between guidance on the exact strength and
track of this low which is the reason confidence is low at this
time.

Gulf of Alaska...

Forecast confidence remains above average for Sunday and then
becomes moderate for Monday and Tuesday. Winds will remain below
gale force with no high seas expected on Sunday. Monday and
Tuesday there is a front moving through the Gulf and will produce
an area of gale force winds. Though there are differences between
guidance on the evolution of this front which makes for moderate
forecast confidence at best.

&&

.LONG TERM FORECAST (Days 4 through 7/Monday through Thursday)...

Amplified troughing travels across the Bering/Aleutians Monday
and Tuesday, weakening as it moves across the Mainland towards the
Gulf. Areas of rain are likely along the Chain, as well as
increasingly gusty winds. Southwest may see periods of heavy
snowfall Monday, with some lingering light snow showers Tuesday
and early Wednesday. Models are hinting at cyclonic development in
the Gulf by Monday night, within the base of the trough. The low
development, in conjunction with the multiple shortwaves tracking
across the Southern Mainland, will bring snow into Southcentral,
with the heaviest snowfall along the North Gulf Coast. A transient
ridge moves into Southwest Alaska overnight Tuesday through early
Wednesday afternoon before the next Russian front approaches the
Southwest Coast. The front reaches the Coast Wednesday, bringing
another round of show showers to Southwest. Simultaneously, a deep
low enters the Western Bering, quickly moving towards the Bering
Strait. The front pushes into Southern Alaska, looking to bring
another batch of widespread snow showers across the Mainland.
Additionally, the GFS is currently indicating a warmer airmass
following the front, which may end up producing areas of rain
along the Southwest Coast, specifically along the AKPen and
Bristol Bay, as well as across Kodiak Island (save the higher
elevations who will still likely see snow)

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Blizzard Warning 155.
MARINE...Storm Warning 175 177.
         Gale Warning 127 173 174 176 178 179 180 181 185.
  Heavy Freezing Spray Warning 121 127 128 129 138 139 150 160
                               180 181 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...NR
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
MARINE/LONG TERM...ED/KM