Blizzard in Alaska, November 19 to 24, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
659 AM AKST Sun Nov 19 2017

FXAK69 PAFG 191559
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
659 AM AKST Sun Nov 19 2017

.SYNOPSIS...
Aloft...
A long wave pattern consisting of a ridge over the Bering Sea and
West Coast of Alaska with a trough over NW Canada and Eastern
Alaska will persist through the week. A series of strong short
wave troughs will move through the ridge and into the West Coast
of Alaska every 2 days or so keeping the very stormy pattern
through the week. The West Coast and Western Interior and Arctic
can expect strong winds, heavy snow, possible blizzards and
possible coastal flooding with each of these storms. The Eastern
Interior will remain cold through the week.

A strong short wave now over the West Coast of Alaska will move
south over the Gulf of Alaska tonight. This is causing high winds
and severe winter weather and high surf over Western Alaska that
will move south later today.

A second strong short wave now over the Sea of Okhotsk will move
to the Eastern Bering Sea Mon PM, and over the West Coast of
Alaska Tue AM, and into the western Interior Tue. This will bring
another round of high winds and winter weather and possible
coastal flooding over Western Alaska.

A third strong short wave will move east over the Bering Sea Wed.

Surface... A low pressure trough from Inuvik to Wainwright will
move just north of the Coast tonight. Stratus, flurries and fog
will persist along this trough.

A 990 mb low over the Chukotsk Peninsula will move to near McGrath
as a 990 mb low by 3pm Sun then move southeast into the Gulf of
Alaska Sun night. An occluded front stretching from this low to
Anvik to King Salmon will move southeast today. An extension of
the occluded front aloft stretches northwest of the low and will
move to McGrath to the Bering Strait by 3pm Sun, and then move
southeast of the forecast area tonight. There will be another 2-4
inches of snow along the track of the low and occluded front, with
light snow lingering along the front aloft. East winds 30g40 mph
on the east side of the low and front area causing blowing snow
and blizzard conditions. Winds turn west 30-40 mph west of the
front. In the southeast quadrant of the low west winds are
gusting as high as 70 mph over zones 213 and 214 today. Winds
will decrease this after noon and evening.

A Strong low in the Sea of Okhotsk will move to just west of
Anadyr as a 978 mb low by 3pm Mon, and to the southern Chukshi sea
as a 975 mb low by 3pm Tue. Expect another round of Rain, snow and
freezing rain with this over zones 213 and 214 Lat Mon and
possible Blizzard over the remainder of the west coast Also expect
south winds 40 kt ahead of the low turning west 40-50 kt southeast
of the low. Will issue more WWA for this Mon after the current
round of storms end.

&&

.DISCUSSION...
Deterministic models have some initialization issues. At H500 in
the ridge over the West Coast of Alaska, ROABS at Kotzebue, Nome,
Bethel and St Paul all show 20m higher heights than indicated by
any of the Model initializations. The IR Sat pic combine with the
Shemya RAOB show that the trough west of the ridge should be a bit
sharper and deeper than models indicate as well. Result is that
the surface features may be a bit stronger than models indicate.

The 06Z surface analysis shows that all models at about 5 mb to
week on the depth of the surface low just north of Provideniya.
This will result in the surface low remaining about 5 mb deeper
than models indicate through 3pm this afternoon, so we will add 5
kt to what model winds would indicate close to the low center
through this afternoon. This bears out with the 10Z Anadyr
observation showing 50g70kt, and quick scat winds of 55kt. Will
have Storm force winds marine zone 210 and public zones 213 and
214 today.

The GFS and ECMF move the strong low from the Bering Strait south
more slowly today then the NAM. Since the low is deeper than
models indicate and will thus likely move more slowly than models
indicate, and thus prefer lingering precip and winds longer today
over the southern Interior than models indicate. After that model
movements are pretty similar through 3pm Mon. After that start to
see significant differences in short wave and associated surface
low strength and location between models. The NAM and GFS are a
bit slower and more southerly with tracking the next strong low as
it moves over NE Russia on Tue than the ECMF. At this point
Prefer the slower NAM/GFS on Tue, but there is much uncertainty.
This uncertainty has much importance on affecting potential for
coastal flooding so needs to be watched closely.

Coastal Hazard Potential Days 3 and 4...
High Surf zone 214 through midnight tonight.West winds gusting to
60 mph today will produce a 3 to 4 foot rise in sea level along
the Coast from Stebbins to Scammon Bay and cause high surf through
tonight. The surge will cause a rise on the Yukon River in the
Yukon Delta.

Potential for Coastal Flooding Along the West Coast
Tue into Wed but still much uncertainty as to occurrence and
locations due to model differences at that time range. This will
need to be watched closely as could be a significant storm.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory for AKZ212-AKZ214.

Winter Storm Warning for AKZ214-AKZ215-AKZ216.

Blizzard Warning for AKZ207-AKZ209-AKZ210-AKZ211-AKZ212-AKZ213.

Winter Weather Advisory for AKZ208-AKZ223-AKZ225-AKZ227.

Heavy Freezing Spray Warning for PKZ200-PKZ210-PKZ215-PKZ220-
PKZ225-PKZ230-PKZ235.

Gale Warning for PKZ200-PKZ215-PKZ220-PKZ225-PKZ230.

Storm Warning for PKZ210.

Small Craft Advisory for PKZ235.
&&

JB NOV 17