Area Forecast Discussion
Issued by NWS Fairbanks, AK

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000
FXAK69 PAFG 161400
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
600 AM AKDT Mon Oct 16 2017

.SYNOPSIS...
Aloft...
A long wave trough stretching from Banks Island to the Bering Sea
will rotate over mainland Alaska into the Gulf of Alaska by Wed
then persist into the weekend with h500 heights falling through
this week. This means that temperatures will fall over all of
Northern Alaska through the week with below normal temperatures
by the end of the week.

A short wave trough stretching from Banks Island to Wrangel Island
will move south overt he North Slope tonight. There is a surface
trough coincident with this. Expect snow with this through
tonight.

A second trough now about 80N will move south over the Western
Arctic Coast Tue, and to Deadhorse to the Yukon Delta Wed. This
will cause a surface low to deepen as it moves over open water Tue
and will be addressed below in the surface section.

Surface...
A 997 mb low over the Gulf of Anadyr with a trough stretching east
over Norton Sound to near Anvik will dissipate tonight. This is
causing scattered rain and snow showers over zones 213 211 212 and
214 that will continue through tonight.

A 990 mb low in the eastern Beaufort Sea will move to Banks
Island as a 990 mb low by 4pm Mon, and then continue moving east.
A surface trough from this low to Barrow will move inland over the
North Slope of Alaska tonight. This is causing snow showers along
the Arctic Coast that will move inland late tonight. Expect 1-3
inches of snow with this. West winds 15-30kt over the Eastern
Arctic Coast will decrease and turn northwest tonight. Over zone
204 will see gusts to 50 mph this afternoon and tonight causing
low visibility in blowing snow.

Low level instability over Interior Alaska will allow isolated
rain and snow showers today through Tue in the southern Interior,
with isolated snow showers in the northern Interior.

A 1000 mb low 600 nm north of Barrow will move to near Barrow as a
991 mb low by 4pm Tue, and to near Coldfoot as a 992 mb low by
4pm Wed. Due to the very cold air at low levels, -12C or colder at
850 mb, expect significant deepening of this low and very gusty
winds on the NW quadrant of this feature along with significant
"Lake Effect" type snow. Expect 2-4 inches of snow and winds
gusting to 40 mph. This will likely cause snow squalls with
periods of low visibility in the squalls. There is a lot of
uncertainty in the location and strength of the low due to its
location in the high Arctic and lack of observations, so it could
be stronger than any models indicate, and it could move onshore
anywhere from Barrow to Deadhorse. Fairly high certainty that snow
and winds will hit from Barrow west with either low track, but a
lower certainty that it could occur from Deadhorse to Barrow if
the low center tracks further east. If low center tracks further
east this could cause a longer duration northerly fetch of strong
cold advection winds over zones 201 and 202 that could lead to
high surf, and this will need to be closely watched.

Snow showers and winds will move over Interior Wed with the low.

Due to the above we have issue WWA for zones 204 this afternoon
into tonight, and for zones 201 and 202 Tue pm into early Wed.
There is potential for WWA in zones 203 and 205 Tue night but this
depends on the low track.

&&

.DISCUSSION...
Deterministic models similar through 4pm Mon, then the NAM and
ECMF keep the low that tracks east across the southern Bering Sea
into the Gulf of Alaska deeper than the GFS. Also, the GFS is much
weaker than the ECMF and NAM on handling the low that is now 600
nm north of Barrow as its moves to near Barrow on Tue. Prefer the
the NAM solution as the low north of Barrow is now at 1000 mb,
and has a strong short wave and very cold low level air
supporting it which will cause the low to deepen rapidly as it
moves over the 600 nm of open water north of the Arctic Coast.
There is still a fair amount of uncertainty on the exact track of
this low which could make landfall anywhere between Barrow and
Deadhorse. The main difference will be that the NAM solution will
manifest in stronger winds over the North Slope Tue and over the
Northern Interior Wed. The NAM solution will also result in more
snow over the North Slope on Tue.

Coastal Hazard Potential Days 3 and 4...
Potential for High Surf from Barrow west Tue night and at Prudhoe
Bay early Wed, but great uncertainty due to feature moving out of
high Arctic and lack of observations.
Potential for high surf at Shishmaref Wed night and Thu.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory for AKZ201-AKZ202-AKZ204.

Heavy Freezing Spray Warning for PKZ240-PKZ245.

Small Craft Advisory for PKZ240-PKZ245.
&&

$$

JB OCT 17



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