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000 
FXAK69 PAFG 202318
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
318 PM AKDT Sun Aug 20 2017

.DISCUSSION...Long wave troughing remains centered over mainland 
Alaska, with the 20/12Z showing the trough pattern consisting of 
a 538 dm low located around 30 miles northwest of Anvik. A short
wave was rotating around the southern periphery of this low,
located at 12Z in the western Gulf of Alaska. A second low with a
534 dm low center was located near the High Arctic around 78.4N 
167.5W. Upper level ridging was located over the western
Aleutians, which extends north through the western Bering and
eastern Siberia. A 565 dm low was located just south of the
Kamchatka Peninsula. At the surface, a 997 mb low was located 180
miles south southeast of Kodiak. A surface ridge of high pressure
extends from the north Pacific into the Bering Sea, extending
through northwest Alaska and through the Beaufort Sea. A weak 1002
mb low pressure system was skirting across the Siberian Arctic
Coast, around 145 miles southwest of Wrangel Island.

The 12Z deterministic models are in good agreement on the overall
pattern through the upcoming week, with long wave troughing
expected to persist over the state. Upper low near Anvik will 
drop south across the Alaska Peninsula this evening, and into the
Gulf late tonight. A short wave rounding the southern side of the
High Arctic upper low will move through the Siberian Arctic Coast
today, to cross the Chukchi Sea tonight to move over the western 
AK Arctic Coast Monday morning. A second piece of energy will move
out of the Chukotsk Peninsua Monday night to the western Seward 
Peninsula Tuesday morning. These two features will effectively 
work to form an upper trough over the western third of the state 
by Tuesday, while squashing the upper ridging over the Bering 
Sea. Additional short waves dropping down the backside of this
newly formed trough from eastern Siberia, combined with the upper
low south of the Kamchatka Peninsula moving east across the
Aleutian Chain toward Bristol Bay, will further act to deepen this
trough Wednesday. Upper level ridging becomes restablished over
the western Bering and east Siberia Wednesday night. 

North Slope/Brooks Range: A weak disturbance will move north into
the eastern Brooks Range tonight, bringing a round of rain to this
region as well as the eastern Arctic Coast. Snow levels will 
remain high around 5000 feet. Easterly flow will continue over the
central and eastern Arctic Coast with a 1016 mb area of high 
pressure over the eastern Beaufort Sea, which will drift off to
the northeast north of Banks Island by Tuesday. This will promote
periods of fog and stratus to persist through tonight, before
winds just off the deck turn more offshore for Monday. A weak 
surface low will pass just south of Wrangel island this afternoon
and move out into the Chukchi Sea tonight, then slowly drift to be
located near Cape Lisburne by late Monday night. 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 late tonight into Monday. The front will
continue to advance east through the eastern half of the North 
Slope and Brooks Range, to bring rain to this region by Tuesday
afternoon. 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, and down to around 3000
to 3500 feet on Wednesday for the central Brooks Range.
 
West Coast/West Interior: Ridge of high pressure will weaken over
the West Coast tonight, as a weak surface low will pass just 
south of Wrangel island this afternoon and move out into the 
Chukchi Sea tonight, then slowly drift to be located near Cape 
Lisburne by late Monday night. 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 Coast and western Seward Peninsula late
tonight into Monday, pushing through the western Interior Monday 
night into Tuesday. 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.
Southerly winds to around 25 knots will accompany the frontal
system through the Bering and Chukchi Sea tonight into Monday
morning, followed by gusty northwest winds to around 30 knots that
will develop on the backside of the low pressure system Monday 
evening into Tuesday. The strength of the wind and fetch looks 
favorable enough for high surf and potential beach erosion for 
Shishmaref developing Monday night and continuing through
Tuesday, before winds turn to the north and diminish Tuesday 
night.

Central and East Interior: Scattered showers are expected for 
Interior Alaska through Monday, with the best chances focused
along the Alaska Range. These showers will be diurnally enhanced,
and isolated afternoon/evening thunderstorms will be possible for
the east Interior through this evening. A weak disturbance will 
move north from the east Interior, which will continue to bring rain
to the southeast Brooks Range, mainly from the Dalton Highway east
tonight. Rainfall amounts look to be lighter compared to 
yesterday, generally up to one half inch or less with the heaviest
amounts around Arctic Village. 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...Low pressure will move 
from Cape Lisburne Tuesday to the eastern Beaufort Sea on 
Wednesday. Northerly winds on the backside of this low could 
produce high surf over the central Arctic Coast by Thursday.

&&

.FIRE WEATHER...No concerns at this time. Slight chance of 
thunderstorms this afternoon and evening from Fairbanks north and
east. Chance of wetting rain remains relatively high in the upper
Yukon Flats and eastern Brooks Range. Some drying for the western
Interior on Monday, but Relative Humidity values remain high and 
will generally be above 40 percent. Sustained winds less than 15 
mph. 


&&

.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-PKZ225-PKZ230-PKZ245.

&&

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