Small Craft Advisory 158, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
344 PM AKDT FRI SEP 16 2016

.DISCUSSION...

Upper Air:
A deep upper low centered about 550 nm north northwest of Barrow
will move on a cyclonic wobbly path to 200 nm north northwest of
Barrow by Saturday afternoon, to 450 nm north of Deadhorse by
Sunday afternoon, and to 500 nm north of the Mackenzie River
Delta by Sunday afternoon. Several short wave troughs rotating
around the upper low will sweep across the Arctic coast
during the next 3 days. A weakening upper low near Nunivak Island
will move to near Dillingham by Saturday afternoon and into the
southeastern Gulf of Alaska by Sunday afternoon. A weak ridge over
the western Bering Sea will move eastward and build into a strong
ridge with the axis extending from the Chukotsk Peninsula to Dall
Point then southward across the western Alaska Peninsula by Sunday
afternoon. The ridge will continue to move eastward through Monday
afternoon, with the ridge axis extending from the Chukchi Sea to
the eastern north Gulf Coast then south southwestward into the
Gulf of Alaska by Sunday afternoon.

Surface...
Several low pressure centers will continue to wobble around
on a cyclonic path over the Arctic Ocean between latitudes 75N
and 79N and longitudes 140W and 170W through Sunday, becoming a
single 980 mb low centered 400 nm north of Demarcation Point by
late Sunday night. This will result in a series of weather fronts
moving eastward across the Arctic coast and a period of moderately
strong west winds across the Arctic coast, with the strongest
winds expected to be over the eastern Arctic coast. A weather
front and associated surface trough will move northeastward
into the northern Gulf of Alaska and into Norton Sound by
Sunday evening. Another weather front and surface trough
will move into the northern Bering Sea by Monday afternoon
and across Norton Sound Monday night.

Arctic Coast and Brooks Range...
The most important issue is the likelihood of elevated or high
surf conditions along parts of the Arctic Coast. From the Barrow
area west to Icy Cape, west winds are expected to increase to 25
to 30 mph late Saturday evening and continue through Sunday night.
The long fetch over ice free waters and the duration of the fetch
will produce waves of 8 to 10 feet offshore. Waves breaking
onshore will produce elevated surf, with a maximum storm surge of
0.7 to around 1 foot from midnight Saturday night to around noon
Monday. We will issue a special weather statement for elevated
surf conditions with a possibility of shoreline erosion. Stronger
winds are expected along the eastern Arctic coast including the
Kaktovik area. Winds in the Kaktovik area are expected to increase
to 25 to 35 mph by Sunday morning and increase to 30 to 40 mph by
Sunday afternoon and continuing through Sunday night before
diminishing Monday morning. The strong winds along with the length
and duration of the fetch will produce waves as high as 8 to 11
feet which will cause high surf conditions as they break onshore.
A maximum storm surge of around 1.4 to 1.5 feet is expected from
around 6 pm Sunday through 6 am Monday. The high waves and
elevated sea levels will produce high surf and beach erosion along
the shoreline north of the village of Kaktovik and along the north
shore of the spit on which the airport is located. Water levels
could rise to a high enough level to cause localized minor
flooding along the eastern end of the spit including the eastern
end of the Barter island airport runway. A high surf advisory will
be issued to address these expected conditions. Mainly snow or
mixed rain and snow along the coast from the Barrow area westward
will spread southward and eastward across the central and western
interior Arctic slope and the central and western Brooks Range
tonight, and taper off the isolated to scattered showers over most
areas by Saturday evening.

West coast...
Isolated to scattered showers are expected over most areas
south and east of Norton Sound tonight and Saturday. A
chance of rain over the central and northern parts of the
Seward Peninsula late tonight and Saturday. An increasing
chance of rain north of the Seward Peninsula tonight,
with rain likely in the lower Kobuk and Noatak valleys
Saturday. An increasing likelihood of rain over much of the
west coast beginning Sunday as the weather front approaches
from the west. South winds increasing to 30-35 kt in Norton
Sound Monday afternoon and continuing through Monday evening
could produce a period of elevated surf with a maximum storm
surge of 2.5 to 3 feet along the northern shore of Norton Sound
Monday afternoon and evening.

St Lawrence Island and Bering Strait coast...
South winds 25 to 35 kt expected on the Bering Strait coast
Monday through Monday night and on St Lawrence Island Sunday
evening through around noon Monday. Elevated surf is
expected on the south shore of St Lawrence Island late
Sunday night through around noon Monday. Rain likely
on the island Sunday through Monday and on the Bering
Strait coast Sunday night into Monday with the incoming
weather front.

Western interior...
isolated to scattered showers over most areas tonight
and Saturday. with rain likely in parts of the upper
Kobuk and Noatak valleys Saturday, tapering off to
isolated showers Saturday night.

Central and eastern interior...
Rain showers, snow showers, or mixed rain and snow showers
are expected over most of the Alaska Range tonight through
Sunday. Around an inch of snow may be possible at higher
elevations on the Denali Park road.

Coastal Hazard Potential Days 3 and 4...
Elevated surf is expected along the northern shore of Norton
Sound is expected Monday and Monday evening, with a maximum
storm surge of 2.5 to 3 feet expected along the north shore of
Norton Sound. Elevated surf is expected along the south shore of
St Lawrence Island late Sunday night through around noon Monday.
See main discussion for shorter term coastal hazard potential.

&&

.HYDROLOGY...
None.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ240-PKZ245.
High Surf Advisory for AKZ204.

&&

RF SEP 16