Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 192355
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
355 PM AKDT Sat Aug 19 2017

.DISCUSSION...No major change to 19/12Z 500 mb pattern with long
wave troughing centered over mainland Alaska, consisting mainly of
a 533 dm low located around 50 miles west of Kotzebue. Several
short waves are embedded within this low. The first of which was
seen rotating around the south periphery of the upper low moving
across the Gulf Coast. A second low/short wave with a 534 dm low
center was located near the High Arctic around 78N 150W, merging
with another 535 dm low near 79N 174E that is moving east out of
the Siberian Arctic. A 560 dm low was located south of the
Aleutians around 185 miles south of Adak, and a 545 dm low was
located on the boarder of Alberta and the NW Territories in
Canada. At the surface, the main weather pattern was dominated by
broad low pressure remaining over mainland Alaska, with several
embedded weaker lows embedded in the long wave upper trough,
including a 1000 mb double low located around 100 miles south of
the eastern Aleutians and a 995 mb low in the High Arctic near 81N
153W. Weak 1016 mb ridge of high pressure was building over the
Bering Sea and far east Siberia extending north into the Chukchi.

The 12Z deterministic models are in good agreement on the overall
pattern through the remainder of this weekend into much of next
week, although the guidance is trending slightly slower with the
progression of the main features. Overall, the weather pattern
will remain unsettled with periods of rain or showers, although
there will be some dry breaks at times. Main upper low west of
Kotzebue will drop south across the west coast tonight, to be
located over the Alaska Peninsula by Sunday evening, and into the
Gulf late Sunday night. The eastern upper low in the High Arctic
will eject to the north toward the North Pole, as the other upper
low moving out of the Siberian Arctic will take its place and
remain nearly stationary through Monday to gradually drift north
on Tuesday. A second short wave that will move out of the Siberian
Arctic has sped up considerably with 12/18Z guidance runs, now
expected to move across Wrangel Island on Sunday evening, to cross
the Chukchi and move over the Northwest Coast by Monday evening,
as short wave ridge builds over the southern Bering at this time.

North Slope/Brooks Range: No major concerns at this time.
Scattered rain showers are expected for the Brooks Range tonight,
greatly tapering off in coverage for Sunday as ridge over western
Alaska strengthens. Snow levels tonight and Sunday will range
from around 2500 feet over the western Brooks Range to around 4500
feet for the eastern half of the range. A weak disturbance will
move north from the east Interior tonight, which will bring a
round of rain the east Brooks Range from the Dalton Highway east
to Arctic Village. Mainly snowfall is expected for Atigun Pass
with minor accumulations expected by late Sunday night. Easterly
flow with a weak ridge of high pressure over the eastern Beaufort
Sea will promote periods of fog and stratus to persist through
this weekend, and over the eastern Arctic Coast possibly through
Monday. IFR for and stratus will diminish as winds will shift
offshore from west to east across the Arctic Coast beginning
Sunday night, as a weak surface low will pass just south of
Wrangel island Sunday afternoon and move onto the western Arctic
Coast somewhere between Point Hope and Point Lay by early Tuesday.
A weather front will extend in front and to the south of this
low, which will bring another round of rain to the western Arctic
Coast and western Brooks Range Sunday night into Monday. The
advancing front will bring a chance of rain Monday night into
Tuesday for the eastern half of the North Slope and Brooks Range.
Showers will wrap around the low circulation over the western
Arctic Coast and western Brooks Range on Tuesday, with snow levels
falling to around 2500 feet.

West Coast/West Interior: The upper low will drift south as an
upper level impulse rotates around the southern periphery of the
low into the southwest Interior. Periods of rain can be expected
over the southwest Interior late this afternoon into this evening,
with lingering showers expected overnight. Scattered to isolated
showers are expected for the remainder of the West Coast, mostly
from the Seward Peninsula south. Ridge of high pressure builds in
the West Coast late tonight and lasts through Sunday night. This
will bring a brief period of rain-free conditions to most of the
West Coast and west Interior Sunday. Short wave trough will
quickly move out of east Siberia Sunday morning, which will spin
up a weak surface low to pass just south of Wrangel island Sunday
afternoon and move onto the western Arctic Coast somewhere between
Point Hope and Point Lay by early Tuesday. A weather front will
extend in front and to the south of this low, which will bring
another round of rain to the Chukchi Sea Sunday night into Monday,
and from the Seward Peninsula north on Monday. Lighter
rain/showers are expected south of the Seward Peninsula. Showers
will wrap around the low circulation over the Chuckchi Sea Coast
and western Brooks Range on Tuesday, as the weather front advances
bringing light rain to the west Interior Monday night/Tuesday.

Central and East Interior: Scattered to numerous showers are
expected for Interior Alaska through Monday. These showers will
be diurnally enhanced, and isolated afternoon/evening
thunderstorms will be possible for the east Interior through
Sunday. A weak disturbance will move north from the east Interior
tonight, which will bring a round of rain to the southeast Brooks
from the Dalton Highway east to Arctic Village Sunday and Sunday
night. Some locally heavy 24 hour totals up to 1 inch are a
possibility, but it does not appear widespread enough to create
major small stream flooding concerns. Some gusty winds will be
possible through Alaska Range passes on Monday, but nothing
significant with gusts expected to remain below advisory criteria.
A weakening weather front moves into the central Interior
Tuesday, helping to refocus an area of light rain or showers here,
to push into the east Interior by Tuesday night.

Coastal Hazard Potential Days 3 and 4...A weather front will move
through the Chukchi Sea on Monday. West northwest winds of around
20 knots behind the front will begin Monday evening to persist
through at least Tuesday. The strength and fetch of the wind
appears favorable enough for high surf and beach erosion in
Shishmaref during this timeframe, and trends will have to be
watched closely for a possible advisory for this area.

&&

.FIRE WEATHER...No concerns at this time.


&&

.HYDROLOGY...Flood Advisory continues for the Tetlin Road, for
the latest information go to www.weather.gov/fairbanks.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Flood Advisory for AKZ224.

Small Craft Advisory for PKZ210-PKZ220.

&&

$$

NTS AUG 17


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