High Surf in Alaska, October 1, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
253 PM AKDT Sat Sep 30 2017

.DISCUSSION...
The 12Z model suite initialized well against the 12z surface
analysis with the exception of the low northeast of Barrow which
verified around 5 mb lower than what was initialized in the model
suite. Position and track of the low north of Barrow verified
well against 18z surface analysis.

Aloft at 500 hpa, a 512 Dam low 400 nm north of Demarcation Point
with a strong shortwave that stretches south through the Yukon
will continue to retreat to the north and east as an upper level
ridge builds over southwest Alaska through Sunday and merges with
a rapidly building ridge over the Gulf of Alaska that builds
over Alaska Sunday evening and into Monday. A strong shortwave
races north along the back of the ridge and will be located over
southern coast of Alaska Sunday evening, the Alaska Range and
southern interior Monday morning. A mountain wave is expected to
develop over the Alaska Range late Sunday evening and Monday and
will brings the potential for strong gap winds through the Alaska
Range passes and a moderate strength Chinook downslope wind event
along the northern foothills of the central and eastern Alaska
Range beginning late Sunday evening and continuing through the day
on Monday. At this point high end advisory level winds are likely
along the northern foothills especially Monday morning. The
models continue to flip flop on timing and duration and strength
of the winds with different models and model runs indicating sub
advisory to Warning level winds. Continue to monitor.

An upper level low drops south and east through the Sea of Okhotsk
Monday and moves over the Kamchatka Peninsula Tuesday and into the
western Bering Sea Wednesday. The strong upper level low moves
east and north over the northern Bering Sea to near St Lawrence
Island Wednesday. The upper level low combined with favorable
dynamics aloft will provide an environment favorable for strong
cyclogenisis over the central Bering Sea late Tuesday and
Wednesday. Computer models continue to indicate a 960 mb or deeper
surface low developing over the central Bering Sea Tuesday and
Wednesday. Model solutions on the location, track and strength
display considerable spread at this time. Continue to monitor.

On the surface a 999 mb low 400 nm north of Demarcation point
continues to move north and east into the high Canadian arctic.
A warm front stretches form near Wainwright to Fort Yukon will
continue to move to the north and east with much of the snow over
the western north slope and western Brooks Range changing to rain
below 3,000 feet. 1 to 2 inches of snow are expected over the
eastern north slope tonight before changing over to rain tomorrow.
Snow will mix with and change over to rain in the eastern Brooks
Range below 2500 feet. 2 to 4 inches of snow are expected over
the Dalton Highway with up to 6 inches of snow expected east of
the Dalton Highway.

Light rain and snow over the northern interior will change to rain
and diminish later tonight. Only a slight chance of rain is
expected over the southern interior. Mostly cloudy skies are
expected over the central and eastern interior Sunday and Monday
as a moderate chinook develops over the central and eastern Alaska
Range. Light rain will move over the YK Delta, west coast and
western interior Monday.

Southwest winds will increase Sunday night and Monday along the
northwest coast and combined with surge values of 1 to 2 feet
over normal tide levels will bring another round of elevated surf
to the northwest coast however wind direction along the coast and
at times off shore will limit wave run up along the northwest
coast. Along the south west facing coast near Kivalina on shore
winds will cause higher wave run up. A high surf advisory has been
issued for this area beginning tonight and continuing through
Sunday night.

Coastal Hazard Potential Days 3 and 4...
Computer models continue to indicate a 960 mb or deeper surface
low developing over the central Bering Sea Tuesday and Wednesday.
Model solutions on the location, track and strength display
considerable spread at this time. Current computer tracks would
bring highest surge level to coastlines south of Hooper Bay
however a change in track further to the north would bring high
surge levels over south and west facing coasts north of Hooper
Bay. Continue to monitor.

&&

.HYDROLOGY...None

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory for AKZ207.

Small Craft Advisory for PKZ210-PKZ220-PKZ225-PKZ230.
&&

CCC SEP 17