Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 201237
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
437 AM AKDT Sun Aug 20 2017

.DISCUSSION...

Models...Good agreement during the short term. They initialized
well against the 20/06Z local surface analysis, but the high over
the Arctic Coast is not as pronounced in the analysis as it is in
the models. Precipitation amounts and location over the eastern
Brooks Range have varied quite a bit the last couple runs, and
that has not changed with the latest solutions. Heaviest
precipitation keeps getting moved further east in successive runs
and is now a bullseye over the Helmut Mountain region with around
one inch today.

Aloft...At 500 hpa...Long wave trough extends from high in the
Arctic to the north Pacific roughly over 160W this morning. A 534
dam low 500 nm northwest of Point Barrow will move northeast to
600 nm north of Point Barrow by Monday morning and 800 nm
northeast of Point Barrow by Tuesday morning. A 538 dam low over
Anvik continues to move south and will be over the Alaska
Peninsula late this evening, and 300 nm south of Kodiak City by
Monday morning, moving east to 200 nm southwest of Yakutat by
Tuesday morning. A 544 dam low 200 nm west of Wrangel Island will
move to 200 nm east of the island by Monday morning as it absorbs
a rapidly moving low that is following it. The low will move over
the northwest Arctic Coast by Tuesday morning at 539 dam. Ridging
over the western Bering Sea will move to the central Bering Sea by
Monday morning with 560 dam heights pushing north over the Gulf
of Anadyr. As the ridge rotates to the east, a shortwave
associated with the low over the northwest coast squashes it as it
moves to lie over the Bering Strait early Tuesday morning, and by
Tuesday afternoon it comes into phase with the low in the Gulf of
Alaska. The low over the northwest coast will continue to deepen
as it moves over the central Brooks Range by Wednesday morning at
535 dam. At 850 hpa...Temperatures will continue to warm a bit the
over most of mainland Alaska, but the low moving over the
northwest coast will start pulling cold air down over the west
coast Monday night with the zero isotherm lying from Barrow to
Hughes to Kaltag and extending west over St Lawrence Island. By
Wednesday morning it will lie from Nuiqsut to Livengood to Emmonak
and south of St Lawrence Island. Temperatures do warm a bit over
the southeast interior to near +10C Monday and Tuesday before
cooling again.

Surface...Pattern remains unsettles with lots of moving parts
across the forecast area. Broad area of low pressure remains south
of the Brooks Range this morning with a 996 mb low 200 nm
southeast of Kodiak City anchoring it and troughing extending
north to the middle Tanana Valley then east. A weak ridge that was
over the Arctic nearshore waters has moved onshore and a 1017 mb
center will develop 100 nm north of Barter Island this morning and
ridging will extend west over the northwest Arctic Coast, then
southwest to a 1023 mb high in the Central Bering Sea. Over the
next 24 hours the high near Barter Island will move east in to the
Beaufort Sea, and the high in the Bering Sea will slip south over
the central Aleutians. This will allow a 998 mb low that is 200
nm southwest of Wrangel Island this morning to move to the central
Chukchi Sea by Monday morning, then over the western Brooks Range
by Tuesday morning with a weather front lying through the Bering
Strait. The low will pick up speed and move east to Demarcation
Point by Wednesday morning dragging the front east across the
forecast area. Low to the south will continue to spread showers
into the interior today as it moves east, but not as much as
yesterday in the Central Interior, then a little drying trend for
Monday and Tuesday, but there may still be some showers moving
around the area.

Arctic Coast and Brooks Range...Cloudy, some fog, some showers,
sounds just like late summer in the Arctic. Open water will
continue to moderate temperatures in the coastal areas, inland
temperatures can easily fall to around freezing if clouds clear
for a while. Fog may be dense at times with poor visibility, but
not expecting any lengthy periods of poor visibility. Onshore flow
will continue with northeast to east winds at 10 to 20 mph
prevailing.

West Coast and Western Interior...Some showers and patchy fog
over the lower Yukon Delta this morning as the upper level low
moves across the area, otherwise the ridging building over the
west coast should provide some breaks in the clouds today and
Monday in advance of the next system that will be moving to the
area late Monday. Winds northwest to northeast at 10 to 20 mph in
the coastal areas, becoming southwest as the ridging slides east.
Inland winds variable to 10 mph in most areas. Temperatures
slightly warmer through Monday then cooling.

Central and Eastern Interior...Showers over most of the area to
one extent or another. Heaviest concentration will be over the
upper Yukon Flats and the eastern Brooks Range east of Arctic
Village where up to one inch of rain may fall today. Cloudy to
mostly cloudy conditions will prevail through the week. Winds will
continue to be generally light and variable though there could be
some gap winds in the Alaska range gusting to around 30 mph.
Temperatures will warm slightly today and Monday, then start
cooling back to highs in the 50s and lows falling into the 40s.


&&

Coastal Hazard Potential Days 3 and 4...The low that moves to
Demarcation Point Wednesday could produce high surf over the
central Arctic Coast Thursday.

&&

.FIRE WEATHER...Slight chance of Thunderstorms this afternoon
and evening north and east of Fairbanks. Showers in the interior
tapering off from the southwest today. Chance of wetting rain
remains relatively high in the upper Yukon Flats and eastern
Brooks Range. Some drying, but Relative Humidity values remain
high and will generally be above 40 percent. Sustained winds less
than 15 mph.

&&

.HYDROLOGY...Rivers steady or trending down in most areas and
additional rain in most areas will not impact them. The exception
will rivers east of Arctic Village and north of Fort Yukon which
could get as much as one inch of rain today. Rivers in this area
could see rapid rises tonight and Monday, but all are expected to
remain well within banks. 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.

&&

$$

SDB AUG 17



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