High Wind Watch 14, NWS Anchorage, AK

502 
WWAK71 PAFC 060059
NPWAER

URGENT - WEATHER MESSAGE
National Weather Service Anchorage AK
359 PM AKST Sun Nov 5 2017

AKZ131-061500-
/O.UPG.PAFC.HW.A.0014.171106T2100Z-171107T0900Z/
/O.NEW.PAFC.HW.W.0013.171106T1500Z-171107T0900Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
359 PM AKST Sun Nov 5 2017

...HIGH WIND WARNING IN EFFECT FROM 6 AM MONDAY TO MIDNIGHT AKST
MONDAY NIGHT FOR VALDEZ AND THOMPSON PASS...

The National Weather Service in Anchorage has issued a High Wind
Warning, which is in effect from 6 AM Monday to midnight AKST
Monday night. The High Wind Watch is no longer in effect. 

* LOCATION...Valdez and Thompson Pass.

* WIND...Northeast 40 to 55 mph with erratic gusts as high as 80 
  mph.
 
* TIMING...Winds will rapidly increase Monday morning then peak 
  Monday afternoon through Monday evening. Winds will then 
  gradually diminish through Tuesday. 

* IMPACTS...Travel may be difficult especially for high profile
  vehicles. Blowing snow may be possible along the roads. Trees 
  may be blown over. Loose debris can be moved and damage 
  property. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A high wind warning means a hazardous high wind event is expected
or occurring. People are urged to secure loose objects that could
be blown around or damaged by the wind.

&&

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
437 PM AKDT Sat Nov 4 2017

.ANALYSIS AND UPPER LEVELS...
The upper level ridge is moving eastward and is over the Copper
River Basin this afternoon. The shortwave digging southward from
the Chukchi Sea is on track to move over the Kuskokwim Valley
tonight and over Southcentral on Sunday. Good northerly flow aloft
is in place behind this trough and that will likely begin to play
a part in the weather over southern Alaska late Sunday into
Tuesday. Surface high pressure remains over most of the Bering Sea
with a front in the western Bering Sea which is progressing
eastward.

&&

.MODEL DISCUSSION...

Models remain in very good synoptic agreement today with all
solutions pointing to a strong consolidated low in the Gulf by
Sunday evening. Timing for snow in Southcentral for tonight into
Sunday is very similar on all models with the upper level low
cutting off by Sunday afternoon and ending the widespread
precipitation.

&&

.AVIATION...
PANC...The VFR conditions this afternoon and evening are the
break from the low clouds and fog that have pestered the area the
past few days. Conditions will lower again as snow moves into the
area tonight. Heaviest snow will likely not be until tomorrow
morning so conditions may remain at MVFR levels a good portion of
the night before dropping to IFR for both visibility and ceilings
for most of tomorrow morning. conditions will slowly improve
Sunday afternoon.

&&

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

All signs continue to point to a decent snow set-up starting
tonight and continuing through Sun for just about all of South
Central. Moisture continues to stream up from the North Pacific
while our upper level trough is progressing over the western half
of the state. Precipitation should start over the southern Kenai
and coastal areas this evening, followed closely by the western
Susitna Valley. Precipitation should start right around midnight
for much of the Anchorage area. Precipitation type at the onset
will prove a bit challenging. Warmer temperatures along coastal
locations (Homer, Seward, etc.) could allow things to start out as
rain before turning to snow by midday Sun. For Anchorage, it does
look like there could be just enough warm southeast flow off of
the Turnagain Arm to cause things to start out as a rain/snow mix
for West Anchorage. This will be quite short-lived though as
down-inlet flow increases right around midnight and all
precipitation should turn over to snow. The best snow accumulation
period looks to be from the early dawn hours Sunday through late
morning. Snow amounts should rather uniform across the area with
generally 3-5" for areas from the northern Kenai Peninsula through
the Susitna Valley. The Matanuska Valley will be on the lower end
of this because of the track of the system. A deformation band
could set up on the west side of the system as cold air starts to
dig in in earnest. Right now it looks as if this would occur over
Mount Susitna and into the Cook Inlet, where a few extra inches
would be possible. By Sun afternoon, snow will taper off to
showers and come to an end by Sun evening.

Behind the snow, expect cold and gusty winds to develop. A strong
offshore gradient will cause winds to rapidly increase Sun
afternoon into Sun night. This will make for very strong winds
through the typical gaps (Thompson Pass, Valdez, Seward, Shelikof)
to start the week. With fresh snow on the ground, this could
create some pockets of blowing snow in parts of South Central.
This event looks to peak on late Mon into Tue, so please see the
long-term discussion for more details.

&&

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

A frontal boundary will continue to slide across Southwest Alaska
tonight. Cold air advection has begun to filter in behind the
front and at some point this evening the cold air advection will
begin to move out ahead of the front. This will allow for rainfall
to transition to snowfall east of Bethel and north of King Salmon.
It currently looks like 2 to 4 inches of snowfall will be possible
near the Alaska Range with only around an inch being observed near
Iliamna. The shot of snowfall will be pretty quick as a strong
upper level trough shifts the front into Southcentral Alaska but
it wouldn't be shocking to see snow showers continue along the
Alaska Range through Sunday evening. Otherwise, a return to more
seasonable temperatures is expected Sunday and into the beginning
of the next work week with clearing skies and another round of
high pressure setting up. This time, with colder air advecting
southward, fog will not be a concern.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

Another day and another front is approaching the western Bering
Sea. A weakening low pressure system over Kamchatka will push a
front into the far western bering Sea late tonight. While this
front will be initially rather unimpressive, it will phase with
another low that will move quickly into the Bering from the north
Pacific Sunday afternoon. This will help bring a swath of 35 to 45
kt winds to the western half of the Bering Sea and an influx of
subtropical moisture. The front will struggle to move eastward as
it clashes with a ridge of high pressure over the eastern Bering
Sea but it should make steady progress eastward through Monday.

&&

.LONG TERM FORECAST (Days 3 through 7: Tuesday through Saturday)...

As the low in the North Pacific shifts further south, deep
northerly flow will establish itself over the Mainland Monday
night. An upper-level wave will linger along the northern Gulf
Coast Monday night through Tuesday night, providing upper-level
support for a fairly strong outflow wind event. The setup for a
mountain wave event Tuesday morning into Tuesday afternoon in the
Valdez area is looking increasingly favorable. We will be
monitoring this potential closely over the next few couple of days
as this could potentially bring warning level winds into the town
of Valdez. Winds will peak Monday night through Tuesday
morning, then generally subside through Tuesday afternoon as the
pressure gradient slackens and a ridge axis moves overhead. By
Tuesday night, the ridge will erode as a series of shortwaves
approach from the west. These shortwaves will bring some more
clouds to Southcentral and a return of the chance for some
isolated showers through Thursday. Offshore flow will return
Friday as another outflow event sets up.

Over Southwest Alaska and the Bering Sea, the dominant ridge will
break down early next week. A front over the eastern Bering Sea
Monday night will weaken as it moves onshore Tuesday, bringing
some rain and snow inland. Behind the front over the Bering Sea,
cold air will begin to filter out of Russia and into the Bering
Sea. This will destabilize the atmosphere and re- introduce
convective showers to the Bering Sea as a series of upper-level
disturbances push east Tuesday through Thursday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale 120 127 130-132 136-138 150 177 178 185 351 411-413.
         Storm 352.
&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...MSO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MC
LONG TERM...RSD