Winter Storm Warning 4, NWS Anchorage, AK

246 
WWAK41 PAFC 310125
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
425 PM AKST Sun Dec 30 2018

AKZ125-311400-
/O.CON.PAFC.WS.W.0004.000000T0000Z-181231T1400Z/
Western Prince William Sound-
Including the cities of Whittier, Seward, Girdwood, 
and Moose Pass
425 PM AKST Sun Dec 30 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 5 AM AKST MONDAY
THROUGH TURNAGAIN PASS...

* WHAT...Heavy snow and blowing snow expected. Winds gusting as 
  high as 45 mph will reduce visibilities to one half mile or less
  at times. Total snow accumulations of 12 to 16 inches are 
  expected through Turnagain Pass.

* WHERE...Turnagain Pass.

* WHEN...Until 5 AM AKST Monday.

* ADDITIONAL DETAILS...Plan on difficult travel conditions. Winds
  gusting as high as 45 mph may cause periods blowing and 
  drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing 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. For the latest road conditions
call 5 1 1 or visit 511.alaska.gov.

&&

$$

AKZ131-311500-
/O.CON.PAFC.WS.W.0004.181231T0600Z-181231T1800Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
425 PM AKST Sun Dec 30 2018

...WINTER STORM WARNING REMAINS IN EFFECT FROM 9 PM THIS EVENING
TO 9 AM AKST MONDAY THROUGH THOMPSON PASS...

* WHAT...Heavy snow and blowing snow expected. Snow will become
  heavy by late this evening and continue through Monday morning.
  Visibilities will be reduced to one half mile or less at times.
  Total snow accumulations of 18 to 24 inches are expected.

* WHERE...Thompson Pass.

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

* ADDITIONAL DETAILS...Plan on difficult travel conditions.
  Localized winds gusting as high as 45 mph will cause areas of 
  blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing 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. For the latest road conditions
call 5 1 1 or visit 511.alaska.gov.

&&

$$

http://www.weather.gov/afc

661 
WWAK41 PAFC 310627 CCA
WSWAER

URGENT - WINTER WEATHER MESSAGE...CORRECTED
National Weather Service Anchorage AK
927 PM AKST Sun Dec 30 2018

AKZ125-311400-
/O.COR.PAFC.WS.W.0004.000000T0000Z-181231T1400Z/
Western Prince William Sound-
Including the cities of Whittier, Seward, Girdwood, 
and Moose Pass
927 PM AKST Sun Dec 30 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 5 AM AKST MONDAY
THROUGH TURNAGAIN PASS...

* WHAT...Heavy snow and blowing snow expected. Winds gusting as 
  high as 45 mph will reduce visibilities to one half mile or less
  at times. Total snow accumulations of 12 to 16 inches are 
  expected through Turnagain Pass.

* WHERE...Turnagain Pass.

* WHEN...Until 5 AM AKST Monday.

* ADDITIONAL DETAILS...Plan on difficult travel conditions. Winds
  gusting as high as 45 mph may cause periods of blowing and 
  drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing 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. For the latest road conditions
call 5 1 1 or visit 511.alaska.gov.

&&

$$

AKZ131-311500-
/O.CON.PAFC.WS.W.0004.000000T0000Z-181231T1800Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
927 PM AKST Sun Dec 30 2018

...WINTER STORM WARNING REMAINS IN EFFECT FROM 9 PM THIS EVENING
TO 9 AM AKST MONDAY THROUGH THOMPSON PASS...

* WHAT...Heavy snow and blowing snow expected. Snow will become
  heavy by late this evening and continue through Monday morning.
  Visibilities will be reduced to one half mile or less at times.
  Total snow accumulations of 18 to 24 inches are expected.

* WHERE...Thompson Pass.

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

* ADDITIONAL DETAILS...Plan on difficult travel conditions.
  Localized winds gusting as high as 45 mph will cause areas of 
  blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing 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. For the latest road conditions
call 5 1 1 or visit 511.alaska.gov.

&&

$$

http://www.weather.gov/afc

408 
WWAK41 PAFC 311404
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
504 AM AKST Mon Dec 31 2018

AKZ125-311515-
/O.EXP.PAFC.WS.W.0004.000000T0000Z-181231T1400Z/
Western Prince William Sound-
Including the cities of Whittier, Seward, Girdwood, 
and Moose Pass
504 AM AKST Mon Dec 31 2018

...WINTER STORM WARNING HAS EXPIRED THROUGH TURNAGAIN PASS...

Snow has tapered to scattered snow showers through Turnagain Pass.
Little additional accumulation is expected. 

$$

AKZ131-311800-
/O.CON.PAFC.WS.W.0004.000000T0000Z-181231T1800Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
504 AM AKST Mon Dec 31 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 9 AM AKST THIS
MORNING THROUGH THOMPSON PASS...

* WHAT...Heavy snow and blowing snow. Additional snow
  accumulations of 2 to 4 inches are expected.

* WHERE...Thompson Pass.

* WHEN...Until 9 AM AKST this morning.

* ADDITIONAL DETAILS...Plan on difficult travel conditions. 
  Winds gusting as high as 40 mph will cause widespread blowing 
  and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing 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. For the latest road conditions
call 5 1 1 or visit 511.alaska.gov.

&&

$$

http://www.weather.gov/afc

951 
WWAK41 PAFC 311741
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
841 AM AKST Mon Dec 31 2018

AKZ131-311845-
/O.EXP.PAFC.WS.W.0004.000000T0000Z-181231T1800Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
841 AM AKST Mon Dec 31 2018

...WINTER STORM WARNING HAS EXPIRED...

The Winter Storm Warning has expired.

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
747 PM AKST Sat Dec 29 2018

.ANALYSIS AND UPPER LEVELS...

We have an upper level trough extending from the Seward Peninsula
to Prince William Sound that is being pushed to the northeast by
a building upper level ridge from the Gulf of Alaska. The surface
low is in the base of this trough in Prince William Sound.
Satellite and radar show a distinct back edge to the precipitation
and higher clouds of this trough. Lower clouds have persisted over
Cook Inlet to the Matanuska Valley today. The ridge is being
pushed northeast in response to the front that is being pushed
northeast toward the Bering Sea coast. This front is from the
large vertically stacked low over the western Bering Sea that is
slowly moving east as it decays. Along this front a low has formed
south of Unalaska that is moving north. This rapidly deepening
low is generating strong hurricane force winds.

Cold, polar air over the eastern Bering is being eroded by the
incoming warmer air with the incoming front. This has not
progressed far north and the Pribilof Islands remain cold enough
to keep precipitation snow and that combined with the strong east
wind is resulting in blizzard conditions.

&&

.MODEL DISCUSSION...

The models finally converged on a unified position and strength
for the intense low heading across the Pribilof Islands late
tonight. The next low in this series is on tap to hit the Alaska
Peninsula Sunday afternoon and the models are in good general
agreement with the strength and position of this storm. The models
show good agreement with the progression of the front toward the
Bering Sea coast and the onset of the snow and wind tonight. There
remains some uncertainty in the models with respect to the
strength of the wind expected with this low as it crosses the
Alaska Peninsula Sunday night. While the models generally agree
on the timing of this, they continue to struggle with the
magnitude of the wind field around the south and west side of this
low. The NAM and GFS over the last couple of model cycles have
been consistent with the movement and magnitude of the low as has
the ECMWF, although the ECMWF has had the weaker low solution.

&&

.AVIATION...
PANC...The main issue for tonight will be the cloud ceiling and
to a lesser degree the visibility. Uncertainty remains with regard
to the cloud deck lifting, though we do expect to be VFR this
evening. We are still on tap for the next low to move up over SW
Alaska and push moisture over Southcentral Alaska. However,
stronger south southeast wind across the Chugach will create a
down slope drying and limit any precipitation. Another concern for
Sunday is the potential for wind shear, at least earlier in the
day until the wind mixes down to the surface.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 2/Tonight
through Monday)...

Weak low-level convergence extending from the Anchorage Bowl
north across the Susitna Valley is bringing a band of light to
moderate snow across the region this evening. The snow will come
to an end tonight as the upper-level shortwave responsible for the
snow continues to lift north and east.

A front extending from a deep Aleutian low will sweep across the
western Gulf tonight then track north to Southcentral on Sunday.
While warmer air will change snow to rain for Kodiak Island, the
arctic air mass in place over Southcentral will ensure
precipitation stays mostly snow across most of the interior and
higher elevations. Along the immediate coast, snow during the
onset of the event will changeover to rain, which will be heavy at
times. An initial southwesterly flow at mid-levels could help
produce a brief period of light snow along the western Kenai
Peninsula north across Anchorage and into the Matanuska Valley
before southeast flow and downslope drying strengthens ahead of
the next storm system moving up from the Pacific. A four to six
hour period of blizzard conditions is also expected Sunday morning
for Portage, eastern Turnagain Arm and portions of the Seward
Highway corridor before the warmer air moves in and changes the
precipitation to rain. A Blizzard Warning has been issued for
these locations.

Guidance is coming into better agreement that a deep low will
track up from the Pacific Sunday and continue northward across
Southwest Alaska Sunday night into Monday morning as it induces a
ridge of high pressure along the Southcentral coast. This track,
and the resultant pressure gradient increase, will bring about a
chinook wind and potential windstorm, especially for Anchorage
and the Matanuska Valley (Palmer). A High Wind Warning has been
issued for the Upper Hillside and along Turnagain Arm for winds
gusting to near 80 mph Sunday evening through early Monday
morning. These winds will also result in significant warming
across the entire region. Gusty winds will make it into Anchorage
proper for a time late Sunday, but the southeasterly wind will
battle with the northerly outflow winds from the MAT-SU Valleys.
This may help tamp down the winds for a time in the northern parts
of the city. These winds will turn to the south then southwest
and diminish Monday morning as both the low and the front lifts
north of the region.

Yet another strong storm looks like it will move up from the
Pacific into the Gulf late Monday. With a completely different
storm track than the prior system, observed weather will be
significantly different. The commonality will be another system
with strong winds and heavy precipitation.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 2: Tonight
through Monday)...

The southwest mainland is about to go on a meteorological roller
coaster ride over the next couple of days as a series of strong
lows move through the area. Tonight, very cold air will remain
entrenched over most inland areas as cloud cover rapidly increases
ahead of a strong warm front to the west. As the front pushes
across the coast tonight, very strong southeasterly winds ramp up
and will be accompanied by heavy snowfall. This combination will
lead to periods of near white-out conditions along the coast, thus
the blizzard warning remains in effect for the Kuskokwim Delta
and Bristol Bay coastal areas. Precipitation should be mostly snow
with this system, though warm air over running cold surface air
could lead to periods of freezing rain early Sunday morning along
the Northern Bristol Bay coast around Dillingham then inland
later in the morning. Temperatures will rapidly rise as the front
pushes through Sunday morning, with most locations warming to or
above the freezing mark by noon. Snow should rapidly diminish as
the front moves through as well.

A brief lull in the action will develop Sunday afternoon before a
strong sub-960 mb low moves north across the southern AKPEN and
into Bristol Bay Sunday evening into Monday morning. The main
impact from this system will be very strong winds, which will
start out from the SE then switch over to the SW as the low moves
north. Winds will really ramp up Sunday evening across the AKPEN
and through the Kamishak Gap across Lake Iliamna. Winds could gust
as high 70 mph in the most favored locations. 40-50 mph wind
gusts will then spread across most of the SW mainland by Monday
morning as the direction switches to the SW. This system will pull
in even warmer air meaning most locations should see a rain snow
mix or just rain, with the exception of the higher elevations.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 2:
Tonight through Monday)...

Multiple storm systems will impact the Bering region over the next
couple of days, continuing the period of stormy weather. For the
Eastern Bering and Aleutians, a strong warm front will continue
sweeping north and east across the region bringing storm force
winds and heavy precipitation. Blizzard conditions will persist
over the Pribilof Islands tonight before the front pushes north
of the islands by midnight, ending snow and warming up the
temperatures to above freezing. Winds will switch to the south but
will not be as strong as they were today, thus the blizzard
warning is now set to expire at midnight. The front will continue
pushing across the Eastern Aleutians and AKPEN tonight, leading to
strong southeasterly winds across the island chain with warming
temperatures, leading to snow changing over to rain from west to
east tonight. Another strong low pushes across the AKPEN tomorrow
afternoon bringing hurricane force winds to the open waters south
of the AKPEN Sunday evening. A swath of heavy precipitation will
accompany the system, but is expected to be mostly rain as the
system will drag up warmer air from the south.

Out west, the strong low over the Western Aleutians will continue
to track east along the island chain, slowly weakening as it
does. This system will continue to bring gale force winds to the
area and widespread rain and snow showers as it slowly meanders
past Atka by Monday.

&&

.LONG TERM FORECAST (Days 3 through 7)...

The run to run consistency with the global models continues to be
atrocious. Generally speaking, anticipate a wet pattern for this
forecast period for the southern tier of Alaska with the
possibility of a rain/snow/freezing rain mix for Southwest Alaska.
The forecast period commences Tuesday January 1st with a broad
trough over NE Russia, the Bering and Aleutians with southwest
flow aloft over most of mainland Alaska. There is a high amplitude
positive tilt ridge from the Eastern Pacific to British
Columbia/Alberta. Meanwhile at the surface at 12z Tuesday, both
the GFS and the ECMWF have a potent low north of the chain, the
GFS places the low NW of St Paul and the ECMWF places the low on
top of the Pribilof Islands with a trough axis extending out of
it. However, the axis/orientation of the trough is completely
different between the GFS and the ECMWF. But the real eye sore is
near the AKPEN/Kodiak and over the Gulf Of Alaska where the GFS
has a bombed-out low and the ECMWF basically has a very weak low.
This GFS cyclone looks a bit aggressive, but maybe three days
from now we will all be singing the praises of the GFS solution
that locked onto the bombed-out low before any of the other
guidance. The lack of consensus is echoed at 500 mb at 12z
Tuesday, which compounds with time. The timing of the
precipitation shield and the gale/storm or even hurricane force
winds are dependent on the placement of the lows that develop and
on the track of the low. There was a hefty amount of blending and
hedging this forecast period as a result of the models poor
performance record. Stay tuned for more details with these
potential winter weather storms. Many of the important decisions
being made with these storms is occurring one or two days out
because the models have not been doing well this winter.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning...101.
		 Blizzard Warning...125 155 161 195.
MARINE...Gales...120 128 129 131 136 137 139 140 141 170 171
				 173 174 176 177 179.
		 Storms...119 125 130 132 138 160 165 172 178 180 181
				  185.
		 Hurricane Force...150 155.
		 Heavy Freezing Spray...160 180 185.

&&

SYNOPSIS AND MODEL DISCUSSION...SA
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KVP
LONG TERM...PJS