Gale Warning 156, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
225 PM AKST Sun Dec 25 2016

.DISCUSSION...
The 12z model suite again initialized the high pressure system
over the Yukon around 5 mb to low and verified around 5 mb too low
as well at 18z. The progged gradient between the high pressure
system and the low pressures trough along the north slopes of the
Alaska Range and west coast as compared to the real gradient is
much too weak leading to weaker model winds progged in the Alaska
Range and the West Coast. We have bumped up winds and associated
hazards to account for the stronger real world winds expected to
continue and develop in these areas. Spread between model families
is minimal as well as from run to run in the short range as well
as the mid range. Model spread remains at reasonable levels in the
extended range.

Aloft at 500 hpa, an upper level ridge over eastern Alaska and
over the Yukon will be move to the east as a 488 DAM low near
Banks Island with a trough extending south and west to near Point
Barrow deepens and drifts to the south and west Monday. The upper
level trough continues to deepen Tuesday over the southern Chukchi
with a closed low around 503 DAM developing over the northern
Chukotsk Peninsula Tuesday. A trough rotating around this low
pushes into the west coast Tuesday with weak zonal flow continuing
over the interior through Wednesday. A high amplitude but flat
topped ridge develops over the northern Pacific and eastern Bering
Sea by late in the weak as a powerful upper level low with strong
dynamics develops over the western and central Bering Sea late
this week. Models continue to indicate the potential for a
significant storm to develop late this week over the central
Bering Sea with the potential for high winds and heavy snow for
western alaska Thursday and Friday.

On the surface, the strong gradient between a 1035 mb high
pressure system over Siberia and a 968 mb low over the central
Bering Sea will continues tighten over St Lawrence Island, the
Bering Strait this evening and along the Chukchi Sea coast
especially north of Cape Thompson later tonight. Winter Weather
Advisories for blowing snow and winds for St Lawrence Island and
the Bering Strait as well as the Point Hope area have been
upgraded to Winter Storm Warnings for high winds and blowing snow
with wind gusts now expected to exceed warning criteria. Winter
Weather Advisories for blowing snow have been extended through
this evening based on winds remaining above advisory criteria over
eastern Norton Sound and the Southern Seward Peninsula. Conditions
are expected to improve later this evening as wind diminish in
these areas.

Winds through the Alaska Range passes are expected to drop below
Advisory levels this evening as an upper level trough which is the
remains of the front extending from the low in the Bering Sea passes
to the north of the Alaska Range and the afore mentioned higher
than progged surface high pressure system over the southern Yukon
retreats to the east. The upper level trough will be the focal
point for scattered snow showers over the central and western
interior and along the west coat south of the Seward Peninsula.
The trough continues to weaken and will produce only light
snowfall. A weak low pressure system moves north along the west
coast and western interior and will produce scattered snow showers
and light snow with generally 1 to 2 inches of snow or less
Tuesday.

Coastal Hazard Potential Days 3 and 4...Long range models
continue to indicate the potential for a significant storm to
develop over the Western Aleutians Wednesday. The low is progged
to deepen to near around 950 mb and move northeast into the
Western Bering Sea Thursday. Strong winds and heavy snow will are
progged to move into the lower YK Delta Thursday morning and the
Seward Peninsula and Bering Strait Thursday afternoon. Strong
winds combined with a long southwest fetch will bring the
potential for high surf along south and west facing coasts that
lack significant ice pack such the southern coast of St Lawrence
Island and the Bering Strait Coast Thursday and Friday. At this
time considerable differences exist between model track, strength
and timing. Continue to monitor for the latest updates on this
potential storm.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ223-AKZ226.

Winter Storm Warning for AKZ207-AKZ213.

Winter Weather Advisory for AKZ211-AKZ212.

Heavy Freezing Spray Warning for PKZ210-PKZ225.

Gale Warning for PKZ210-PKZ220-PKZ225.

Brisk Wind Advisory for PKZ200-PKZ230.
&&

CCC DEC 16