Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 182349
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
349 PM AKDT Fri Aug 18 2017

.DISCUSSION...The 18/12Z 500 mb pattern continued to show long
wave troughing centered over mainland Alaska, consisting mainly of
a 529 dm low located around 175 miles northwest of Point Hope.
Several short waves are embedded within this trough, the most
prominent rounding the south side of the trough running through
the eastern Gulf of Alaska nearing the BC coast. A second
low/short wave with a 535 dm low center was located around 250
miles west of Banks Island or around 75.8N 137.9W. A third, weaker
short wave was over the northeast Interior and southeastern
Brooks Range, with a fourth located over Norton Sound and nearing
the YK Delta. At the surface, the main weather pattern was
dominated by broad low pressure centered over mainland Alaska,
with several embedded weaker lows/troughs across the state
situated beneath their aforementioned upper level counterparts.

The 12Z deterministic models are in good agreement on the overall
pattern through this weekend, and remain in fair agreement into
the mid range with some minor differences in the strength and
position of the minor features. Overall, the guidance continues
to suggest long wave troughing to persist across the state through
next week, promoting an overall wet and cool weather pattern.
Largest upper low northwest of Point Hope will drop south across
the west coast, to be located over the Alaska Peninsula by late
Sunday evening, and into the Gulf on Monday. Upper low west of
Banks Island will continue to move to the northwest, to merge with
another short wave move east out of the Siberian Arctic, to form
a 536 dm low near 79N 162W by Sunday evening. A second short wave
will move out of the Siberian Arctic across Wrangel Island on
Monday, to cross the Chukchi and move over the Northwest Coast by
early Tuesday, as short wave ridge builds over the southern Bering
at this time.

Periods of rain are expected to affect the West Coast tonight
into this weekend as upper low moves south over the West Coast
toward the AK Peninsula. Snow levels are expected to range between
1000 to 1500 feet over northwest Alaska and the Seward Peninsula,
which will lead rain mixing with and changing to snow at times
over the higher elevations of the Seward Peninsula as well as the
Brooks Range, mainly during the overnight hours. As of now only
minor accumulations are expected. Scattered to numerous showers
are expected for Interior Alaska for the next several days, aided
this evening by the YK Delta short wave pushing inland over
southwest Alaska and an advancing cold front moving through the
western Interior. These showers will be diurnally enhanced, and
isolated afternoon/evening thunderstorms will be possible for the
east Interior through Sunday. Weak high pressure will build over
the southern Bering Saturday night, which will expand over the
west coast into Sunday. This will diminish the threat for showers
over the western third of the state for a brief time. Short wave
to move over the northwest coast early Tuesday will spawn a weak
area of low pressure that will cross the Bering Strait Sunday
night to bring more showers to the West coast late Monday into
Tuesday. For the North Slope, easterly flow will promote periods
of fog and stratus to persist there through this weekend, as high
pressure moving over the Bering on Saturday extends into the
Beaufort Sea and strengthens Saturday night.


Coastal Hazard Potential Days 3 and 4...High surf is expected to
continue between Wales and Shishmaref through tonight, and is
expected to diminish early Saturday morning as winds subside and
turn more northerly. See ongoing High Surf Advisory for more
details.

&&

.FIRE WEATHER...No major concerns under cool, wet weather pattern.


&&

.HYDROLOGY...The Tanana River near Tok and Tetlin has dropped
considerably during the past 2 to 3 days and overland flow
causing flooding near the Tetlin Village Road and high water along
the Alaska Hwy should continue to recede over the next several
days. However given the extent of the flooding, it is uncertain
when the flood waters will dissipate completely, and is expected
to linger for at least another week.

&&

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

Small Craft Advisory for PKZ220.


&&

$$

NTS AUG 17



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