High Wind Watch 15, NWS Anchorage, AK

998 
WWAK71 PAFC 121336
NPWAER

URGENT - WEATHER MESSAGE
National Weather Service Anchorage AK
436 AM AKST Sun Nov 12 2017

AKZ131-130300-
/O.CAN.PAFC.HW.A.0015.171113T0100Z-171113T0900Z/
/O.NEW.PAFC.HW.A.0016.171113T1500Z-171115T0300Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
436 AM AKST Sun Nov 12 2017

...HIGH WIND WATCH NOW IN EFFECT FROM MONDAY MORNING THROUGH 
TUESDAY AFTERNOON...

The National Weather Service in Anchorage has issued a High Wind
Watch, which is in effect from Monday morning through Tuesday
afternoon. 

* LOCATION...City of Valdez and Thompson Pass.

* WIND...Northeast winds 40 to 60 with possible gusts to 80 mph.
  Thompson Pass will see higher sustained winds, but gusts in 
  both the Pass and City of Valdez may reach 80 mph.

* TIMING...Strong winds are expected to increase again late this
  afternoon and increase further to near Warning levels Monday
  morning. These warning level winds may persist until late
  Tuesday afternoon and then slowly diminish. 

* IMPACTS...Travel may be difficult. Trees may be blown over. 
  Loose debris can be moved and damage property. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A high wind watch means there is the potential for a hazardous
high wind event. People are encouraged to closely monitor this
weather situation. Preparation for this potentially dangerous
weather event should begin now. 

&&

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 AM AKST Sat Nov 11 2017

.ANALYSIS AND UPPER LEVELS...

A stagnant, but quite amplified upper level pattern is in place
across Southern Alaska this morning. For Southwest Alaska and the
entirety of the Bering, a sprawling ridge of high pressure and
warm air aloft is in place. For far eastern Alaska, a trough is
slowly departing the area. In between, a strong 125 kt jet is
slowly pushing eastward. The next system and associated shortwave
that will affect the area is exiting eastern Russia. Under the
ridge, fog and/or low stratus is entrenched across much of the
Kuskokwim Delta region, but thus far has not made much progress
to the lee of the Kuskokwim Mountains. Across the Bering, the
center of the surface high is centered west of Dutch Harbor. All
of the flow is northerly across the eastern Bering and the Alaska
Peninsula; whereas broad southerly flow is transporting moisture
into the front coming off of Russia over the western Bering.

For Southcentral, a very wintry air mass is in place, supported by
the light snow pack over much of the area. Thus, the primary
concern is very strong gap wind flows, especially through the
Barrens, Thompson Pass, and the Copper River Delta. The cold air
is being drawn off mainland Alaska into the Gulf around the west
side of a developing low. The cold air picking up moisture from
off the Gulf is causing widespread ocean-effect cloud-bands over
much of the western Gulf.

&&

.MODEL DISCUSSION...

The models remain in excellent agreement through the short-term
forecast as the pattern remains quite steady-state. As such,
continued gap wind flows, the development of a new low over the
north central Gulf Sunday night, and the broad pattern are well
handled, and confidence is high. Where confidence wanes is
concerning the duration and intensity of the expected fog across
Southwest Alaska and Bering, which thus far has been quite
variable. Also, determining when and how strong the strongest
winds through the gaps of Southcentral is also a challenge as the
peaks of the winds coincide with small-scale mountain wave
features not well resolved by any of the models.

&&

.AVIATION...
PANC...VFR conditions will persist. Gusty north winds will persist
through the day, then diminish tonight.

&&

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

Wind. That is the main forecast issue for the next few days. The
gusty winds along the north Gulf coast will weaken a little bit
Saturday night into Sunday before increasing once again. Winds
will mix down along the Copper River and down Cook Inlet as well.

One non-wind question is whether there may be some fog that can
develop in Cook Inlet Saturday night after winds diminish. At this
time it looks like the low-level atmosphere will be sufficiently
dry to discourage it, but it cannot be entirely ruled out.

The gusty winds on the west side of Shelikof Strait are
resuspending some ash from the Katmai/Novarupta eruption from
1912. This ash is expected to diminish this afternoon as winds
will start to diminish some in that area. However, until
sufficient snow cover arrives, resuspended ash is likely to occur
with each bout of strong winds.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The Southwest remains situated between low pressure to the north
and a ridge to the south through early next week. Influence from
the low to the north brings increased precipitation mainly to the
Kuskokwim Delta and Valley as disturbances dive to the south late
Saturday through Sunday. Fog will be a challenge, especially
along the coastal areas as a stable air mass associated with the
ridge drifts slowly east. Ridging will shift inland Monday into
Tuesday keeping the region in a drier regime heading into the
middle of the next work week.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Two low pressure systems send multiple fronts toward the Bering
which slowly break the ridge down over the central waters heading
into next week. A subtropical influence brings a warm surge
through the northern Bering which keeps precipitation all rain
with the forthcoming fronts. Gale force winds and moderate rain
are expected along the frontal boundaries as they move through.
The biggest challenge through the next several days is
distinguishing the multiple frontal boundaries as embedded short
waves aloft keeps ongoing precipitation in the short range
forecast as abundant moisture streams up from the Pacific.

&&

.LONG TERM FORECAST (Days 3 through 7)...
From Sunday evening onward, the extended forecast will be
a steady state continuation of the current conditions, mainly dry
and colder across the southern mainland. The dominant feature in
the models is an upper level ridge centered over the Bering Sea.
The next downstream longwave trough is well into the Canadian
Arctic, leaving much of Alaska in northerly jet scenario between
these two features. Several shortwave troughs will come through
the flow within the jet, but any precipitation associated with
them should stay on the windward side of the Alaska Range.
Generally this pattern is a cold and dry one for southcentral
Alaska with gusty gap winds along the coast. Expect high
temperatures in the 20s inland and 30s along the coast with lows
in the single digits and teens. Over the southwest mainland,
fronts coming through the ridge will bring periods of snow and
northwesterly winds.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gales: 121 127 128 130 131 132 150 175 176 177 185 413

&&

SYNOPSIS AND MODEL DISCUSSION...JPW
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KH
LONG TERM...ML