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Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
516 am akdt Tue Jun 18 2019

Discussion...

Synopsis...isolated thunderstorms and showers will continue south
of a line from Eagle to Fox to Ruby in the central and eastern
interior during the afternoon and evening hours. Isolated
thunderstorms and scattered showers for the middle Yukon valley
south of Galena, the interior Seward Peninsula, and the lower
Yukon Delta the next couple days. Warmer and drier conditions over
much of the forecast area as ridging aloft builds over the state
from the northwest and the south. A weather front will move south
to the central Arctic coast early Wednesday morning bringing low
stratus ceilings to the central and eastern Arctic coast by
Wednesday afternoon. The Arctic plains will remain warm and dry
with partly cloudy conditions.

Models...18/00z solutions are in good agreement through 48 hours,
then have some issues with the low over the southwest Mainland
breaking down. Precipitation solutions are in good agreement, so
will use a blend leaning toward the NAM, with a nudge to the sref
to increase probabilities. Maintaining continuity with the wind
forecast by only nudging the current database with the namdng.
Convective indicies showing more instability than the last few
days, especially in the lower Yukon Delta with the upper level low
in the area lifted indicies are 0 to -2 and cape values area as
much as 400 j/kg. The remainder of the areas south of a line from
Eagle to Livengood to Huslia to Shishmaref has marginally unstable
conditions that will produce isolated convective activity.

Aloft...at 500 hpa...the stacked 516 dam low that has been over
the eastern Beaufort Sea is finally moving off to the northeast
over the Canadian archipelago dragging the trough over the state
over the Yukon territory. A 550 dam low that developed over the
eastern Brooks range has move over the lower Yukon Delta this
morning at 548 dam and will move over Bethel this afternoon at 556
dam. Ridging is building in over the Northwest Arctic coast,
Arctic plains, and south over the central interior this morning as
a 567 dam high develops over the southwest Arctic. By this
afternoon the high will move over the Northwest Arctic coast with
a ridge axis extending southeast over Anaktuvuk Pass and Eagle. By
Wednesday morning the low over Bethel will weaken to 558 dam,
while the high will move southeast over the central Brooks range
at 569 dam with a 569 dam high over Glennallen and ridging
extending south over the Pacific. A wave spinning around the low
in the Canadian archipelago will sweep south to lie along 75n. The
wave will continue southeast to be over the eastern Arctic coast
by Wednesday afternoon. As the wave continues to dig south,
ridging will build north over the western Arctic plains, and the
Northwest Arctic coast, while ridging over the central and eastern
interior builds to 574 dam. At 850 hpa...temperatures over the
forecast area generally +5c to +10c and will be warming to +6c to
+13c by Wednesday afternoon and continue to warm through Thursday
to +8c to +15c over most of the area. The exception will be the
lower Yukon Delta which will cool Thursday to around +3c. The
warmest temperatures will be over the eastern interior and the
eastern Brooks range Thursday.

Surface...a weather front will persist along the north slopes of
the Alaska Range with a 1008 mb low developing in the upper Tanana
Valley, a 1007 mb low in middle Tanana Valley, and a 1003 mb low
in the lower Yukon Delta. High pressure over the Arctic will
weaken as another weather front moves south into the area, then
east. A 1020 mb high will develop over the western Arctic and move
over the Arctic coast Monday. A 995 mb low in the North Pacific
will move to the southwestern Gulf of Alaska Monday. Weak high
pressure will persist over the southeast Panhandle.

Arctic coast and Brooks range...some stratus and fog east of
Point Barrow along the coast will slowly pull offshore this
morning. Mostly clear inland over the plains with warm and dry
conditions. To the west of Umiat temperatures will rise into the
lower 70s today with relative humidity values falling to around 30
percent. Onshore flow will limit temperatures within 20 miles of
the coast east of Wainwright to the upper 30s and lower 40s for
highs today. Winds generally northeast to east at 5 to 15 mph with
slightly stronger winds on the Northwest Arctic coast at 10 to 20
mph with some gusts to 25 mph. A weather front will move south to
the Arctic coast

West Coast and western interior...will be a fairly active day for
thunderstorms and showers in the inland lower Yukon Delta, south
of Galena in the middle Yukon, and the inland Seward Peninsula.
Warmer and drier over the next few days in the Noatak and Kobuk
basins and from Galena north in the middle Yukon valley. Near red
flag conditions in the Noatak and Kobuk basins. Winds generally
less than 15 mph, but expect some gusty winds, and small hail with
thunderstorms.

Central and eastern interior...warmer and drier over the northern
interior today will spread southeast tonight and Wednesday.
Isolated thunderstorms and showers mainly south of a line from
Eagle to Fox to Ruby today. Winds generally light and variable as
they swing around from northeast to west.

&&

Coastal hazard potential days 3 and 4...none.

&&

Fire weather...warmer and drier conditions will spread over the
forecast area over the next couple days as ridging aloft builds
over the state from the northwest and from the south. Increased
potential for wetting rains in the lower Yukon valley south of
Galena, and the lower Yukon Delta with scattered showers and
isolated thunderstorms. Also expect isolated thunderstorms and
showers mainly south of the Yukon river and on the Seward
Peninsula. Low relative humidity values are also expected in the
Arctic plains with values falling into the 20s. Relative humidity
recovery overnight will be good.

&&

Hydrology...Walker Fork of the fortymile river saw a jump of
about 1.5 feet Monday, but has leveled off and will be falling.
Smaller creeks in the goodpaster, Tanana, and fortymile basins
rose quickly as well Monday, but there have been no reports of any
being out of banks. Rainfall has ended, and all will be falling
the next few days. Expecting some heavier rainfall with
thunderstorms and showers over the middle Yukon valley south of
Galena, and the lower Yukon Delta, so expect some streams to run
high the next few days.

&&

Afg watches/warnings/advisories...

None.

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