Heavy Snow in Alaska, November 11 to 13, 2017

Northern Alaska Forecast Discussion...UPDATED
National Weather Service Fairbanks AK
422 PM AKST Fri Nov 10 2017

Updated for Table for Winter Storm Warnings

SYNOPSIS...
Aloft...
A long wave ridge over the Bering Sea and Western Alaska will
persist through the weekend then build north from the Bering Into
the high Arctic then move west late next week as troughing forms
over Northern Alaska late next week. Several very strong short
waves will make their way east over the top of this ridge
flattening the flow and bringing strong storms with warm air,
plenty of moisture, and strong winds and possible coastal flooding
with periods of heavy snow over Northern AK through the weekend.
Temperatures will drop over eastern Alaska next week.

A weakening short wave from north of Barrow to Denali Park will
move to Barter Island to Delta Junction by 3am Sat, and then east
of the Alcan border by noon Sat. Light snow east of this trough
will drop 1-2 inches. Snow will end and clouds will clear west of
the trough.

A second and much stronger short wave now over Kamchatka will move
to Wrangel Island to the Central Bering Sea by 3pm Sat, over NW
Alaska Sat night, and over the Eastern North Slope and Eastern
Interior Sun. This will push a strong surface low and cold front
along with high winds and snow east with it. This will be
addressed below in the surface section. Strong ridging will build
over Western Alaska Sun night and Mon causing snow to end and
temps to fall.

Surface...
A 996 mb low 300 nm north of Barrow will move to 300 nm north of
Prudhoe Bay as a 1005 mb low by 3am Sat, to 300 nm north of
Barter Island as a 1011 mb low by 3pm Sat, then dissipate. An
arctic cold front extending south from this low to Prudhoe Bay to
Cape Lisburne will move east to the Alcan Border by midnight
tonight then move east. West winds 25g35kt along the front will
spread east with the front tonight. Winds will decrease slowly
behind the front. Snow showers with spread east with the front.
From Barrow west the cold air over warm water will cause snow
showers to be heavier there and keep the WWA in affect through
this evening. To the east of Barrow snow showers will not be as
heavy snow conditions should remain slightly better.

A 980 mb low in the Sea of Okhotsk will move to 200 nm west of
Wrangel Island as a 998 mb low by 3am Sat, to 100 nm north of
Wrangel Island as a 991 mb low, to 400 nm northwest of Barrow as a
989 mb low by 3am Sun, to 150 nm northwest of Barrow as a 1000 mb
low by 3pm Sun, to Prudhoe Bay as a 1012 mb low by 3am Mon, and
to POint Thompson as a 1021 mb low by 3pm Mon. A strong occluded
front with this low will move northeast to the Dateline by 3pm
Sat, to Point Franklin to Huslia to the Yukon Delta by 3am Sun, to
Inuvik to Fort Yukon to Denali by 3pm Sun, then move east of the
Alcan Border Sun night.

Expect south winds 25-35kt with gusts to 50kt at Cape Lisburne and
the Bering Strait ahead of the front along with warm advection
that will cause mixed rain and snow along the west coast that
will tun to all snow as the front moves inland. Expect 3-6 inches
of snow with the front over NW Alaska and the North Slope Sat PM
into Sun, and over the eastern Interior Sat night and Sun. Will
see higher amounts zones 208 217 and zones 227 and 225. Will see
near Blizzard conditions along the Coast from Kotzebue north Sat
pm into Sun, with precip starting as snow and blowing snow,
changing to rain near the front, then back to all snow after the
front moves east.

Along the front expect winds to turn west 25-40 kt along the
front, then northwest 25-40kt west of the front. The strongest
winds will be closer to the low center north of Point Hope. This
still looks to produce a storm surge starting Saturday evening of
5-6 ft zones zones 209 210 affecting Kotzebue and Deering, and 3
to 5 ft in zone 207 affecting Shishmaref, Kivalina and Point Hope.
This also will produce a storm surge of 4 to 6 feet in zone 201
affecting Cape Lisburne to Wainwright, where it will produce
minor flooding and major erosion due to the strength, 600 nm fetch
length and duration of the northwest Gales. Since the low is
tracking over Barrow, it appears as though Barrow will miss the
strongest winds and that the winds that occur will not last as
long, so will issue a high surf for Barrow for Sat night and Sun.

&&

.DISCUSSION...
Models initialize about 5 mb too weak on the low north of Barrow,
and we will bump winds up 3-5 kt along the Arctic Coast today and
tonight as a result. Otherwise models initialize well and show similar
solutions through 3pm Sun. After that time the NAM keep a surface
low north of Barrow which the GFS and ECMF do not. Prefer the GFS
and ECMF solutions as a ridge building aloft over that area Sun
night and Mon should see as high at the surface, not a low.

Coastal Hazard Potential Days 3 and 4...
Along the front expect winds to turn west 25-40 kt along the
front, then northwest 25-40kt west of the front. The strongest
winds will be closer to the low center north of Point Hope. This
still looks to produce a storm surge starting Saturday evening of
5-6 ft zones zones 209 210 affecting Kotzebue and Deering, and 3
to 5 ft in zone 207 affecting Shishmaref, Kivalina and Point Hope.
This also will produce a storm surge of 4 to 6 feet in zone 201
affecting Cape Lisburne to Wainwright, where it will produce
minor flooding and major erosion due to the strength, 600 nm fetch
length and duration of the northwest Gales. Since the low is
tracking over Barrow, it appears as though Barrow will miss the
strongest winds and that the winds that occur will not last as
long, so will issue a high surf for Barrow foe Sat night and Sun.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Coastal Flood Watch for AKZ201-AKZ207-AKZ209-AKZ210.

High Surf Advisory for AKZ201-AKZ202-AKZ202-AKZ211-AKZ212-AKZ213-
AKZ214.

Winter Storm Warning for AKZ201-AKZ205-AKZ207-AKZ208-AKZ217.

Winter Storm Watch for AKZ202-AKZ203-AKZ206.

Winter Weather Advisory for AKZ201-AKZ202-AKZ209.

Heavy Freezing Spray Warning for PKZ215-PKZ230-PKZ240.

Small Craft Advisory for PKZ210-PKZ220-PKZ230-PKZ235-PKZ240.

Brisk Wind Advisory for PKZ245.

Gale Warning for PKZ210-PKZ220-PKZ225-PKZ230.
&&

JB NOV 17