Winter Storm Watch 3, NWS Anchorage, AK

431 
WWAK41 PAFC 082204
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
104 PM AKST Mon Mar 8 2021

AKZ101-091115-
/O.CON.PAFC.WS.A.0003.210310T1500Z-210311T1800Z/
Anchorage-
Including the cities of Anchorage, Eagle River, Indian, 
and Eklutna
104 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH THURSDAY MORNING THROUGH THURSDAY MORNING FOR THE
ANCHORAGE BOWL AND HILLSIDE...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 7 
  inches possible.

* WHERE...Anchorage.

* WHEN...From Wednesday morning through Thursday morning.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ111-091115-
/O.CON.PAFC.WS.A.0003.210310T0600Z-210311T0900Z/
Matanuska Valley-
Including the cities of Palmer, Wasilla, Sutton, and Chickaloon
104 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY EVENING
THROUGH WEDNESDAY EVENING THROUGH WEDNESDAY EVENING FOR THE
MATANUSKA VALLEY...

* WHAT...Heavy snow possible. Total snow accumulations upwards of
  12 inches possible, especially near Hatcher Pass.

* WHERE...Matanuska Valley.

* WHEN...From Tuesday evening through Wednesday evening.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.

* ADDITIONAL DETAILS...Snow across the area will vary widely, with
  higher amounts expected near Hatcher Pass and the mountains and
  lower amounts expected in the Matanuska Valley.
 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ125-091115-
/O.CON.PAFC.WS.A.0003.210309T1500Z-210311T0600Z/
Western Prince William Sound-
Including the cities of Whittier, Seward, Girdwood, 
and Moose Pass
104 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY MORNING
THROUGH WEDNESDAY EVENING THROUGH WEDNESDAY EVENING...

* WHAT...Heavy snow possible. Total snow accumulations of 6 to 
  14 inches possible.

* WHERE...Western Prince William Sound including Seward.

* WHEN...From Tuesday morning through Wednesday evening.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ145-091115-
/O.CON.PAFC.WS.A.0003.210309T1500Z-210310T1800Z/
Susitna Valley-
Including the cities of Talkeetna, Willow, and Cantwell
104 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY MORNING
THROUGH WEDNESDAY MORNING THROUGH WEDNESDAY MORNING FOR THE
SUSITNA VALLEY...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 
  11 inches possible.

* WHERE...Susitna Valley.

* WHEN...From Tuesday morning through Wednesday morning.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

http://www.weather.gov/afc

015 
WWAK41 PAFC 082347 CCA
WSWAER

URGENT - WINTER WEATHER MESSAGE...CORRECTED
National Weather Service Anchorage AK
247 PM AKST Mon Mar 8 2021

AKZ101-091115-
/O.COR.PAFC.WS.A.0003.210310T1500Z-210311T1800Z/
Anchorage-
Including the cities of Anchorage, Eagle River, Indian, 
and Eklutna
247 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH THURSDAY MORNING FOR THE ANCHORAGE BOWL AND HILLSIDE...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 7 
  inches possible.

* WHERE...Anchorage.

* WHEN...From Wednesday morning through Thursday morning.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ111-091115-
/O.COR.PAFC.WS.A.0003.210310T0600Z-210311T0900Z/
Matanuska Valley-
Including the cities of Palmer, Wasilla, Sutton, and Chickaloon
247 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY EVENING
THROUGH WEDNESDAY EVENING FOR THE MATANUSKA VALLEY...

* WHAT...Heavy snow possible. Total snow accumulations upwards of
  12 inches possible, especially near Hatcher Pass.

* WHERE...Matanuska Valley.

* WHEN...From Tuesday evening through Wednesday evening.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.

* ADDITIONAL DETAILS...Snow across the area will vary widely, with
  higher amounts expected near Hatcher Pass and the mountains and
  lower amounts expected in the Matanuska Valley.
 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ125-091115-
/O.COR.PAFC.WS.A.0003.210309T1500Z-210311T0600Z/
Western Prince William Sound-
Including the cities of Whittier, Seward, Girdwood, 
and Moose Pass
247 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY MORNING
THROUGH WEDNESDAY EVENING...

* WHAT...Heavy snow possible. Total snow accumulations of 6 to 
  14 inches possible.

* WHERE...Western Prince William Sound including Seward.

* WHEN...From Tuesday morning through Wednesday evening.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ145-091115-
/O.COR.PAFC.WS.A.0003.210309T1500Z-210310T1800Z/
Susitna Valley-
Including the cities of Talkeetna, Willow, and Cantwell
247 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY MORNING
THROUGH WEDNESDAY MORNING FOR THE SUSITNA VALLEY...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 
  11 inches possible.

* WHERE...Susitna Valley.

* WHEN...From Tuesday morning through Wednesday morning.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

http://www.weather.gov/afc

388 
WWAK41 PAFC 090324
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
624 PM AKST Mon Mar 8 2021

AKZ125-090430-
/O.CAN.PAFC.WS.A.0003.210309T1500Z-210311T0600Z/
Western Prince William Sound-
Including the cities of Whittier, Seward, Girdwood, 
and Moose Pass
624 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH IS CANCELLED THROUGH WEDNESDAY EVENING...

An SPS has been issued in replacement of the watch. 

$$

AKZ101-091500-
/O.CON.PAFC.WS.A.0003.210310T1500Z-210311T1800Z/
Anchorage-
Including the cities of Anchorage, Eagle River, Indian, 
and Eklutna
624 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH THURSDAY MORNING FOR THE ANCHORAGE BOWL AND HILLSIDE...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 7 
  inches possible.

* WHERE...Anchorage.

* WHEN...From Wednesday morning through Thursday morning.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.

* ADDITIONAL DETAILS....

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ111-091500-
/O.CON.PAFC.WS.A.0003.210310T0600Z-210311T0900Z/
Matanuska Valley-
Including the cities of Palmer, Wasilla, Sutton, and Chickaloon
624 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY EVENING
THROUGH WEDNESDAY EVENING FOR THE MATANUSKA VALLEY...

* WHAT...Heavy snow possible. Total snow accumulations upwards 
  of 12 inches possible, especially near Hatcher Pass.

* WHERE...Matanuska Valley.

* WHEN...From Tuesday evening through Wednesday evening.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.

* ADDITIONAL DETAILS...Snow across the area will vary widely, 
  with higher amounts expected near Hatcher Pass and the 
  mountains and lower amounts expected in the Matanuska Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

AKZ145-091500-
/O.CON.PAFC.WS.A.0003.210309T1500Z-210310T1800Z/
Susitna Valley-
Including the cities of Talkeetna, Willow, and Cantwell
624 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM 6 AM AKST TUESDAY
THROUGH WEDNESDAY MORNING FOR THE SUSITNA VALLEY...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 
  11 inches possible.

* WHERE...Susitna Valley.

* WHEN...From Tuesday morning through Wednesday morning.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.

* ADDITIONAL DETAILS...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

http://www.weather.gov/afc

331 
WWAK41 PAFC 090650
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
950 PM AKST Mon Mar 8 2021

AKZ145-090800-
/O.CAN.PAFC.WS.A.0003.210309T1500Z-210310T1800Z/
Susitna Valley-
Including the cities of Talkeetna, Willow, and Cantwell
950 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH IS CANCELLED THROUGH WEDNESDAY MORNING FOR
THE SUSITNA VALLEY...

See the Special Weather Statement for more details on this
upcoming snowfall event.

$$

AKZ111-090800-
/O.CAN.PAFC.WS.A.0003.210310T0600Z-210311T0900Z/
Matanuska Valley-
Including the cities of Palmer, Wasilla, Sutton, and Chickaloon
950 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH IS CANCELLED THROUGH WEDNESDAY EVENING FOR
THE MATANUSKA VALLEY...

See the Special Weather Statement for more details on this
upcoming snowfall event.

$$

AKZ101-090800-
/O.CAN.PAFC.WS.A.0003.210310T1500Z-210311T1800Z/
Anchorage-
Including the cities of Anchorage, Eagle River, Indian, 
and Eklutna
950 PM AKST Mon Mar 8 2021

...WINTER STORM WATCH IS CANCELLED THROUGH THURSDAY MORNING FOR
THE ANCHORAGE BOWL AND HILLSIDE...

See the Special Weather Statement for more details on this
upcoming snowfall event.

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
532 AM AKST Mon Mar 8 2021

.ANALYSIS AND UPPER LEVELS...

In the upper levels, a positively tilted trough with a broad low
near the Kamchatka Peninsula extends its axis from the western
Bering and south across the western Aleutians. The associated
baroclinic front is moving east towards the AKPEN and into
Southwest AK. WV/IR imagery shows an impressive deep fetch of
warm, moist air lifting north from the Pacific. Radar indicates
precipitation ahead of the front moving into Norton Sound and the
Kuskowim Bay Coast. Ahead of this front, a high amplitude ridge is
setting up nicely over the Southern Mainland with its axis
extending from the Arctic Ocean to the North Pacific. Downstream
of the ridge, a vertically stacked low continues rotating over the
eastern Gulf, with latest ASCAT pass (scatterometer wind)
capturing small craft winds south of Prince William Sound to the
central and eastern Gulf. The nighttime microphysics shows low
stratus/fog north of the Alaska Range and a some high clouds
passing overhead. Otherwise, conditions are relatively quite
across Southcentral. One interesting feature is some suspended
glacial silt captured on satellite overnight drifting southward
from the Copper River Delta thanks to gusty winds from a healthy
north-south pressure gradient persisting since yesterday.

&&

.MODEL DISCUSSION...

Model guidance are in relatively decent agreement with the
synoptic features and are still on track with the active weather
pattern for the Bering/Aleutians and Southern Mainland for this
week. However, latest model solutions are still struggling to
resolve the development, strength, and movement, of a triple point
low forming along a frontal boundary near Kodiak Island, and the
resultant weather over the Southcentral coast. The other minor
discrepancies, although not too impactful, are the multiple meso-
lows forming over the Bering on Tuesday in the wake of the
aforementioned Kamchatka low.

&&

.AVIATION...
PANC...VFR conditions with patchy fog this morning. A chance of
intermittent MVFR vis possible through late morning. Light
northerly winds will continue. Clouds will increase overnight but
remain VFR.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 to 3: Today
through Wednesday Night)...

Conditions will remain clear and dry across Southcentral through
the overnight hours and into early morning Tuesday. Outflow winds
continue this morning, but are on the downward trend from Seward
to Whittier. Winds are still gusty for Valdez and the Copper
River Delta, but are expected to diminish through the day as the
pressure gradient relaxes and the winds aloft shift more
southerly as the upper-level ridge moves over the region.

As the ridge shifts east, the upper-level trough upstream over the
Bering will also shift east. At the surface, a frontal system that
is currently draped over the eastern Bering will move over
Southwest Alaska. By late Monday, the front will begin to weaken
as it makes its way toward the Alaska Range. The front, however,
is tapping into a deep fetch of moisture from the north Pacific.
This will allow precipitation to overspread Kodiak Island by late
Monday evening, pushing north over the southern Kenai Peninsula,
Cook Inlet, and the Susitna Valley by early Tuesday morning. For
Kodiak, the precipitation should be mainly in the form of rain.
For Homer and Seward, precipitation will likely start as snow
before changing to rain. Farther inland, enough colder air should
remain in place for the precipitation to stay all snow. By Tuesday
afternoon, some light snow should make it to the Anchorage Bowl;
however, it does appear that a cross-barrier flow will develop as
a newly formed triple point low tracks along the eastern Kenai
Peninsula. This flow would allow for some downsloping and limit
precipitation chances for places like Anchorage and Palmer
Tuesday afternoon through Wednesday morning before the low lifts
into Prince William Sound as the upper-level flow shifts more
northerly.

Right now, it looks like areas north and west of Willow in the
Susitna Valley could see up to a foot of snow through late
Wednesday. Hatcher Pass will could also see up to 18 inches of
snow. Upwards of a foot of snow could also fall within Portage
Valley and Turnagain Pass. The higher elevations around Prince
William Sound and the eastern Kenai Peninsula, though, look to
see the largest snow accumulations with this system.

The current forecast comes with a caveat, though, and it is this:
There are still quite a bit of detail to be ironed out with this
system, as models have yet to reach any consensus as to the
strength and track of the aforementioned low. For example, the 6z
GFS differs greatly from its previous run and has a much deeper
low entering the northern Gulf. While there would still be a
period of downsloping with this system, the winds aloft shift
northerly sooner than the NAM and GEM. Thus, Anchorage and Palmer
could see a second round of snow develop sooner than advertised by
the NAM and GEM. In addition, while all models have the low
eventually entering Prince William Sound, the stronger GFS
solution would likely keep the bulk of the snow from Whittier to
Cordova, with the extended northerly flow also bringing more snow
into Turnagain Pass. The NAM continues to advertise a weaker low
drifting slightly more into western Prince William Sound by late
Wednesday into Thursday. This solution would favor the development
of a snow band over Anchorage and allow for higher snow totals
than the GFS is suggesting. The NAM is also indicating the
potential for higher snow amounts along the Anchorage Hillside as
the flow turns northwesterly with cold air advection and moisture
lingering over the area. Nonetheless, given a blend of the two
models mentioned, it looks right now like 2 to 4 inches of snow is
possible for the Mat Valley, the potential for up to 6 inches of
snow for Anchorage with higher amounts for the Hillside, and 6 to
8 inches of snow for the western Kenai Peninsula.

This system begins to weaken by THursday, but may stall out over
the Prince William Sound with snow showers continuing across much
of Southcentral.

&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2: Today through
Tuesday night)...

The long-awaited front from the Bering brought rain/snow mix
since last night into early this morning along the Kuskokwim
Delta Coast, and blowing snow conditions there as well. The front
maintains a west to east track, which will bring increased
snowfall over the region with heavier amounts along the Kuskokwim
Delta Coast and Bristol Bay today. Warm temperatures combined
with deep southerly winds mixing ahead of the front will yield to
mostly rain over portions of AKPEN this morning, then
transitioning to snow later in the afternoon. Meanwhile, snow
remains in the forecast for Bristol Bay through the lower
Kuskokwim Valleys through tonight. A few isolated surface troughs
from the Bering Sea combined with cold air advection reaching -16
to -22 degrees Celsius at 850 mb could bring increased sky
coverage and light snow along the Y-K Delta on Tuesday and
Tuesday night. For now, will continue monitoring this situation
closely before making new updates for POP and QPF.

&&

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

Water vapor shows a good amount of moisture across the Bering and
Aleutians except a narrow pocket of subsident dry air trailing
eastward toward Dutch Harbor this morning. A few surface troughs
over the Bering combined with cold air advection will produce
scattered to numerous light snow through the forecast period. An
upper-level trough from western Aleutians could potentially
increase the chance of expanding the freezing spray coverage on
Tuesday and Tuesday night. In the meantime, freezing spray will be
mainly focused over the west and north of Pribilof Islands today
through Tuesday.

&&

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

Bering: A series of troughs with locally up to small craft winds
will cross the Bering from west to east on Wed, with small craft
or lower westerlies expected away from the troughs. Westerly winds
could locally be as high as gales on the south side of each
trough, but confidence for the track and timing of each wave is
low at this time. Seas on Wed up to 10 feet. Another front will
approach the western Bering by Thu, with southerly gales spreading
into the western Bering Thu morning into early Fri. Seas building
to up to 20 ft across the western Bering by Thu and Fri. A North
Pacific low may approach the southern Bering and Central Aleutians
on Fri, but track and timing for this next low remains uncertain.
Expect potential for winds to increase to high gales to possibly
low storms over parts of the central to western Bering for Fri,
however exact timing and track of enhanced winds will depend on
the low track.

Gulf of Alaska: A low will move into the central Gulf and then
into or just south of the Prince William Sound on Wednesday.
Widespread westerly small craft to gale force winds will spread
across the central and southern Gulf south of the low center
through Thu. Seas building from 10 to 15 feet from Wed to Thu. The
low center will dive south towards the southern Gulf on Fri with
small craft to gale force winds continuing and becoming
northwesterly over the western gulf through Fri. Seas building to
20 feet in the western Gulf on Fri.

&&

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

The large scale pattern from long term guidance remains in decent
agreement for the Bering, Gulf and mainland AK, but some
discrepancies do emerge across mainly the Bering by Saturday.

A longwave trough is likely to become the dominant influence over
the mainland by Thursday and Friday this week, and the preceding
warm spell over Southcentral early in the week will likely be cut
short as a cold, Arctic air mass spills in from the northwest.
This pattern will favor much colder and drier than average
conditions over mainland AK from Wednesday to Friday, with
offshore flow and the potential for stronger outflow winds for the
typical spots near the North Gulf Coast from Thursday to
Saturday. Longwave ridging will develop into the eastern Bering,
while low pressure and troughing will persist in the northern and
western Bering. Models diverge with the handling of a stronger
shortwave rounding the base of this trough, with varying degrees
of northeast progression of the wave depicted by operational
models on Friday and Saturday. Despite the uncertainty, this will
generally favor active and stormy conditions over the western
Bering with multiple rounds of rain/snow and stronger southerly
winds.

By Sunday, model agreement continues to lessen with global models
trying to progress the western trough towards the Southwest/AKPEN
while the longwave ridge moves farther east into the mainland
with the Arctic air beginning to retreat up into the Yukon. This
could lead to a warming trend beginning over mainland AK with the
potential for another frontal system to move up the AKPEN into
southcentral. However, the progress of this next system and
related warming will greatly depend on how quickly the upstream
ridging and surface high pressure associated with the cold air
mass erode or advect east. This is a dynamic models can be overly
optimistic about, especially looking this far out in time, so the
cold and dry pattern for Southcentral could still linger on for
longer into next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 155,161.
MARINE...Gale Warnings 155 160 165 180 181.
         Heavy Freezing Spray Warning 185 411.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MF/TM
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
MARINE/LONG TERM...AS

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
747 AM AKST Mon Mar 8 2021

AKZ181-091800-
Alaska Peninsula-
Including the cities of Cold Bay and Sand Point
747 AM AKST Mon Mar 8 2021

...TRACE ASHFALL POSSIBLE IN THE VICINITY OF VENIAMINOF...

The Alaska Volcano Observatory has detected continued activity
and low level ash emission in webcam and satellite data from the
Veniaminof Volcano located near Chignik. Any ashfall near Chignik
and Castle Cape is expected to be of trace amounts.

Surface winds are expected to briefly be out of the west early
this afternoon gradually turn southerly by mid to late afternoon.
Any potential ashfall would be north and east volcano.