High Wind Watch 5, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
331 PM AKDT Fri Aug 10 2018

.DISCUSSION...
Presently the weather is fairly quiet and typical for this time of
year through our forecast area. Some light showers are present in
the Eastern Interior. Some locations have intermittent low
ceilings on the West Coast. The North Slope has widespread low
ceilings, patchy fog, and light rain. While conditions are typical
right now, that will change this weekend for all areas except the
North Slope with the remnants of Typhoon Shanshan entering our
forecast area. The remnants of Shanshan will be the dominant
weather feature when it enters our forecast area, encompassing
much of the state.

Synopsis...
A long wave trough over the Bering Sea will dive south through
Saturday as a long wave ridge over the North Pacific builds north
over Mainland Alaska. This pattern becomes progressive on Sunday
with the trough moving over mainland Alaska by Monday. The pattern
will remain progressive next week with a ridge building back over
AK by late next week. This means that the West Coast and Western
Interior of Alaska will be wet and windy through the weekend, then
trend drier next week. The North Slope will remain cool and wet
through the weekend then trend drier and warmer next week. The
Southeast Interior will be dry and warm through the weekend with
chinook winds developing along the Alaska Range, then becoming wet
and cooler next week.

Models are in agreement in the short term and seem to be handling
most features reasonably well. The real question will be how they
pan out with a system of tropical origin entering our forecast
area. Right now models are starting to come together on the storm.
All have about the same storm track. However, they still differ in
placement of the low center, which will influence which areas will
see the most amount of rain and where the highest winds will be.

Surface...

Shanshan...Former Typhoon Shanshan is east of Hokkaido and south
of the Kuril Islands. It will move to near Dutch Harbor as a 977
mb low by 4am Sun, and to near Cape Newenham as a 981 mb low by
4pm Sun, then over the SW Interior Monday, and to near Denali
Tuesday. The remnants of Shanshan will influence most of our
forecast area. This will bring significant rain to SW Alaska Sunday,
with 1-2 inches of rain possible with this feature. An exception
for rainfall will be the Chinook zone of the SE Interior Sunday
and Monday, due to downsloping from the Chinook setup. Also expect
N-NE gale force winds along the West Coast Sunday into Monday.

Interior...
The Interior will be quiet with just some isolated showers and
patchy morning fog until Sunday. Showers today are associated with
a trough pushing east. After it exits, a weak front will move in
from the southwest that will be from the low currently in southwest
Alaska, creating showers through the weekend. A shift in the
weather is then expected to occur ahead of the arrival Shanshan.
Chinook wind conditions will kick up on Sunday for both Windy and
Isabell Passes in the Alaska Range. The latest forecast has winds
gusting to advisory level beginning Sunday midday and lasting
until early Monday morning. As SPS has been issued for winds and
will issue the advisory within the next day, after we have a look
at a couple more model runs to hone in on the wind speeds a little
more. Rain is expected Monday into Tuesday when Shanshan moves
into the Interior, we will continue to watch this feature and
tailor the forecast in the next couple of days.

West Coast...
A weak area of low pressure moving through southwest Alaska will
continue to bring rain tonight tapering to rainshowers tomorrow
from the Y-K Delta and southwestern Interior, when it then
dissipates. The front from this low will push into the Interior
over the weekend. Expect 0.25 inch of rain with this front.
Shanshan will enter the West Coast Sunday, bringing wind and rain
with it. Details are in the section above regarding the storm
itself. Winds through the Bering Strait and Chuckhi Sea will also
be influenced by the storm, with winds turning to a northerly
direction and picking up in speed. This will push water towards
the north coast of the Seward Peninsula, creating the potential
for high surf around Shishmaref. We will monitor the situation and
is an advisory if need be.

North Slope...
A low pressure trough currently located around Deadhorse will push
east through tonight. Scattered rain and snow showers with this
trough will diminish to isolated mixed rain and snow.

A ridge of high pressure from the Chukchi Sea to Barrow to Barter
Island will persist through tonight, then move just north of the
coast Sat and Sun. This will cause areas of fog along the coast
to persist through the weekend.

Coastal Hazard Potential Days 3 and 4...
High surf possible north sides of St Lawrence Island and Seward
Peninsula Mon-Tue.

&&

.FIRE WEATHER...
Most areas will have received and will continue to receive enough
moisture that fire weather activity will remain low. The one area
that bears watching is the Yukon Flats as that region has seen
little rain this summer.

&&

.HYDROLOGY...
Flood Advisory continues for Mile 6 Tetlin Rd with high water
likely through the weekend. High water is expected on rivers in
the Tanana Valley through the weekend. However, rivers have all
crested and are starting to fall across the Interior. Expect rises
next week as remains of Typhoon Shanshan moves across Interior.

&&

BJB AUG 18