Wind Chill Advisory 2, NWS Anchorage, AK

509 
WWAK42 PAFC 100059
WSWALU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
359 PM AKST Thu Feb 9 2023

AKZ155-100200-
/O.CAN.PAFC.WC.Y.0002.230210T0400Z-230210T1900Z/
Kuskokwim Delta-
Including the cities of Bethel and Nunivak Island
359 PM AKST Thu Feb 9 2023

...WIND CHILL ADVISORY IS CANCELLED...

Temperatures overnight tonight are expected to remain too warm for
wind chills at or below -40 to occur. Wind chills as cold as -30
will remain possible as winds pick up through early Friday
morning.

$$

AKZ195-101400-
/O.CON.PAFC.BZ.W.0002.230210T0100Z-230210T2200Z/
Pribilof Islands-
Including the city of Saint Paul
359 PM AKST Thu Feb 9 2023

...BLIZZARD WARNING REMAINS IN EFFECT UNTIL 1 PM AKST FRIDAY...

* WHAT...Blizzard conditions expected. Total snow accumulations of
  1 to 3 inches. Winds gusting as high as 65 mph.

* WHERE...Pribilof Islands.

* WHEN...Until 1 PM AKST Friday.

* IMPACTS...Plan on slippery road conditions. Widespread blowing 
  snow could reduce visibility to one quarter mile or less at 
  times.

* ADDITIONAL DETAILS...Snow will spread into the Pribilofs this 
  afternoon and evening as northeast winds increase and persist 
  through Friday afternoon. The worst conditions and strongest 
  winds are expected for Saint George, with falling snow 
  expected to remain much lighter towards Saint Paul.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Warning means severe winter weather conditions are
expected or occurring. Falling and blowing snow with strong winds
and poor visibilities are likely. This will lead to whiteout
conditions, making travel very hazardous. If you must travel,
have a winter survival kit with you. If you get stranded, stay
with your vehicle.

&&

$$

AKZ161-101400-
/O.CON.PAFC.WW.Y.0013.230210T1000Z-230211T0200Z/
Bristol Bay-
Including the cities of King Salmon, Dillingham, Naknek, 
and Pilot Point
359 PM AKST Thu Feb 9 2023

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 1 AM TO 5 PM
AKST FRIDAY FROM DILLINGHAM NORTH AND WEST...

* WHAT...Snow and blowing snow expected. Total snow accumulations
  of up to 8 inches. Winds gusting as high as 40 mph. Reduced 
  visibilities to one-half mile.

* WHERE...Bristol Bay, from Dillingham north and west.

* WHEN...From 1 AM to 5 PM AKST Friday.

* IMPACTS...Plan on difficult travel conditions. Areas of blowing
  snow could significantly reduce visibility. The cold wind 
  chills as low as 30 below zero could cause frostbite on exposed 
  skin in as little as 30 minutes.

* ADDITIONAL DETAILS...Snow will begin early Friday morning and 
  continue through Saturday morning. Northeasterly winds are 
  expected to increase through Friday morning, bringing the 
  potential for significant visibility reductions in blowing 
  snow. Visibility should improve by Friday afternoon as winds 
  diminish.

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
617 PM AKST Wed Feb 8 2023

.ANALYSIS AND UPPER LEVELS...

In the upper levels the jet stream continues to move near the
Aleutian chain and dips southeast before recurving north towards
Southeast Alaska. Several lows and shortwaves are moving along the
jet with a storm force low over the northern Pacific approaching
the western Aleutians, while a weaker low near Atka is enhancing
winds to near small crafts and producing a few snow showers.
Otherwise, colder than normal across the Aleutians and Bering
with temperatures in the 20s to near freezing. Another shortwave
is moving into southwestern Alaska producing a few snow showers.
Across the Gulf a weak surface low south of Seward along with a
shortwave trough extending across the Kenai Peninsula into the
northern Gulf is producing snow showers across the Prince William
Sound area. While an area of weak low pressure and low level
convergence is producing light snow from the western Kenai
Peninsula and north into Anchorage and parts of the Mat-Su.

&&

.MODEL DISCUSSION...

Model guidance continues to be in good agreement with the synoptic
scale features. The forecast challenge will winds and
precipitation type along the Alaska Peninsula and Aleutians as
a storm force low tracks near and just south of the Aleutian
chain on Thursday. Expect the warming to overwhelm the cold air in
place pretty quickly, so will lead toward lower snow accumulation
guidance along the Aleutians.

&&

.AVIATION...
PANC...Light snow will continue through this afternoon with MVFR
to IFR conditions. Snow accumulation through today will be an inch
or less. The snow is expected to end by the late afternoon or
early evening hours. The big question is whether skies will clear,
in which case fog/stratus (IFR/LIFR) could quickly form - or
whether cloud cover (MVFR/VFR) will hold in and limit fog
formation. With persistent cyclonic flow aloft, seems more
favorable for some sort of higher cloud deck to hold in place.
Will keep an eye on satellite and webcams and adjust the forecast
as the more likely scenario tips its hand.

&&

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

Tonight's forecast begins with the timing of snow ending. It
appears as if the current round of snow will end this evening,
then the forecast question becomes, how quickly does the cloud
cover clear out. There does not appear to be much to clear the
current cloud cover out. The Kenai Peninsula has a better chance
to clear out which will drop their temperatures much more than the
places that keep clouds to the north. Lows will drop into the
single digits in places that clear, teens for cloudy areas. The
chances for fog also ramp up where the clouds clear. Tomorrow
looks like the start of a full scale pattern change from the weak
feature cyclonic flow we have been in for the last several weeks.
First, however, is a short period of offshore gap winds in
response to a stronger system near the Panhandle. These will be
limited in strength by the lack of upper level support, peaking
in the 30 to 40 kt range.

The next system/front to affect the area is a very strong Aleutian
low pressure that swings a front into the Gulf on Friday, pushing
onto the north Gulf coast late Friday. The system as a whole will
be in a weakening phase as it approaches, but will bring gale-force
winds to much of the area, with large swells behind the front due
to dynamic fetch from the north Pacific. The Gulf coast will see
a decent period of snow from the front, but inland areas will be
mainly dry from moisture blocking and downslope drying.

&&

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

One more day of quiet but still bitterly cold conditions is on
track for most of the outlook area, save for a few widely scattered
snow showers moving in with a couple weak waves embedded in an
upper trough moving overhead this evening. For places that clear
up and allow the surface to radiate out, very cold overnight lows
the -10s will be possible overnight tonight. Areas of low stratus
that moved over the Kuskokwim Delta earlier today could keep
temperatures a little warmer, depending on how much this deck is
able to break up overnight. Otherwise, expect another partly to
mostly sunny and clear day on Thursday.

A significant shift in the pattern will begin from Thursday night
into Friday as a strong, storm force low sends a front northeast
along the Alaska Peninsula, pushing into Bristol Bay on Friday.
Strong, gusty northeast winds will develop as a tight offshore
pressure gradient develops north of the low and approaching front,
with the strongest winds gusting up to 40 mph expected to peak
across Bristol Bay by the early afternoon hours. Snow will spread
north with the front as well, mainly for areas that will favor
upslope enhancement around the Kilbucks, while much of the rest of
Bristol Bay will stay drier due to downsloping drying off of the
Aleutian and Alaska Ranges. Areas of blowing snow are likely
farther west, including around Dillingham and Togiak, until winds
begin to decrease as the front weakens and the as the parent low
approaches from the southwest early on Saturday. The heaviest
snowfall amounts will also be focused near Dillingham, with around
5 to 8 inches of new accumulation through Saturday morning. Areas
of snow will linger near the the weakening surface low as it
moves over Bristol Bay on Saturday, while colder air begins rush
back into the Lower Kuskokwim Valley and Kuskokwim Delta and push
temperatures lower through Saturday evening.

&&

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

In the near term through tonight, a cluster of weak lows and
associated snow showers will continue to drift across the
Aleutians with generally weak winds. A much more active pattern
will begin by tomorrow, as a strong North Pacific low deepens to
around 955 mb on its approach to the central Aleutians. Strong
easterly winds gusting to around 75 mph at the peak remain
expected along the low's front across the central parts of the
Aleutian Chain, where a High Wind Warning remains in effect
beginning early Thursday. Storm force sustained east to northeast
winds will spread into much of the southern Bering as the low
runs up against high pressure focused over the northern Bering and
Siberia, with sustained winds of 50 kts expected to reach all the
way up to Saint George by Thursday night. The low's frontal
boundary will weaken as it moves into the eastern Aleutians and
up the southern Alaska Peninsula, resulting in slightly weaker
wind gusts peaking between 55 and 65 mph as it moves across on
Friday afternoon and evening. The High Wind Watches earlier in
effect have been cancelled, with confidence increasing that strong
and gusty winds will still occur along the front, but remain below
warning thresholds.

The other aspect of this system will be the heavy precipitation
amounts with the broad deformation band following the systems's
occluding front as it begins to wrap around the center of the low.
Temperatures will initially be cold enough for snow ahead of the
frontal passage for a few hours across most of the eastern
Aleutians, but a changeover to rain is likely within a few hours
after precipitation onset as temperatures warm through Thursday
night. The warm air following the occlusion aloft may fall just
short of reaching Adak, where several inches of very wet, slushy
snow will be possible through Thursday evening. Given that
temperatures will likely be hovering at or just above freezing for
most of the duration of heavier snow, widespread blowing snow is
not expected to develop until later on Friday morning as the low
moves into the Alaska Peninsula and as colder temperatures dive
south into the Aleutian Chain. Farther north across the Pribilofs,
temperatures will remain colder and well below freezing for the
duration of the event, resulting in blizzard conditions developing
on Thursday, especially across Saint George where the highest
snowfall amounts are expected. Please see the Blizzard Warning in
effect for the Pribilofs for additional details.

Between Friday and Saturday, more cold air will spill into the
Bering behind the low as it steadily weakens to below gale force.
Widespread heavy freezing spray will develop with this very cold,
northerly wind, with extreme freezing spray rates greater than 4
cm/hr possible close to the ice edge through Saturday.

&&

.LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)...

A progressive pattern will amplify by mid-week, pushing a series
of storm force lows and fronts through the forecast area. Run to
run consistency is above average, with model solutions remaining
similar to yesterday, lending confidence to the long term forecast.
Sunday morning, a low entering the Gulf of Alaska will push a
front to the north Gulf coast, bringing a round of heavy
precipitation. The track of the low will serve to keep much of
the inland areas dry, with little warm air expected to work its
way into the mainland. This will keep most precipitation snow,
though there is a chance of rain at low elevations along the
immediate coast.

Model guidance continues to indicate that a weak front on the
back side of the low will bring light snow to Southwest Alaska,
with some potential to move into Southcentral as early as Sunday
evening. This is one of the most uncertain aspects of the long
term forecast, though snow accumulations appear to be limited to
a few inches at most. Uncertainty stems from the potential for a
deep cut-off low to be centered over Western Alaska on Sunday,
which would aid in providing lift and instability for precipitation.
It would also correspond to much lower temperatures for Southwest
Alaska as well, with the EC and GEM suggesting 850 mb temperatures
as low as -30C in tandem with the cut-off low. However, the
weaker depiction of this feature in GFS suggests uncertainty in
how cold temperatures will get. Regardless, cold air will help to
drive strong winds out of gaps on the south side of the Alaska
Peninsula and along the western Gulf. These winds are likely to
gust to storm force, and in localized areas storm force winds may
be sustained. Gap winds diminish Monday night as the low in the
Gulf weakens. Shower activity decreases along the north Gulf coast
as well, and the decaying front leaves much of the southern
mainland dry by Monday night.

At the same time, a strong storm force, or potentially hurricane
force, low in the North Pacific passes south of the Aleutian
Islands. The low track has nudged a bit closer to the island chain
with a more northerly model consensus compared to yesterday. Its
front pushes across the central and eastern Aleutians on Monday,
bringing easterly winds as strong as storm force. This also looks
to be another potential significant snowfall event for the
islands, with more cold air in place over the Bering Sea ahead of
the low. Snow moves up along the Alaska Peninsula into Bristol Bay
and over Kodiak Island on Tuesday. There will be some potential
for the low to track into the southern Gulf, allowing its front to
move up along the north Gulf coast bringing another round of
precipitation, with only a limited amount spreading inland. Then,
a strong front off another deep low near the Kamchatka Peninsula
brings a strong southerly push of warmer air late on Tuesday. This
should be enough for precipitation to switch over to rain as the
front sweeps from the western Aleutians to the central Aleutians
through Wednesday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning 187.
         Blizzard Warning 195.
MARINE...Heavy Freezing Spray Warning 139 160 179 180 185.
         Storm Warning 170 172 173 174 175 176 177 179.
         Gale Warning 132 150 155 160 165 171 180.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...RC
SOUTHCENTRAL ALASKA...MTL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AS
LONG TERM...CQ