Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 172240
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
140 PM AKST Wed Jan 17 2018

.DISCUSSION...

Models...Big picture solutions yesterday handled things quite
well. Digging down to the details they were not bad, but also not
real good. Solutions today have good run to run continuity and are
in quite good agreement. Surface analysis at 17/18Z matched up
well against the 12Z solutions. Will be using a blend for the
short term surface winds, and lean toward the SREF solution for
precipitation probability.

Aloft...At 500 hpa...Flow aloft has weakened, but remains mainly
from the south. Low that developed over Fairbanks last night has
moved over the Central Brooks Range at 519 dam. Weak ridge has
developed over the interior with the low that moved over Kodiak
Island last night weakening to 520 dam. The low over the Brooks
Range will move northwest over Point Lay by Thursday morning at
516 dam, then merge into a trough over Wrangel Island that is
associated with a 498 dam low to the west of Wrangel Island. A
weak trough will remain over the West Coast Thursday, then move
over the Western Interior as a 535 dam high builds over the
Northern Bering Sea. The low over Kodiak will slowly move north
to be over Anchorage by Friday morning at 519 dam. Ridging will
persist to the east of the area, but a 520 dam low will develop
and move northeast across the Yukon Territory tonight, then move
move north of the Northwest Territories. By Saturday morning
longwave trough will develop over the state with a 502 dam low 250
nm north of Point Lay with troughing extending south over Kodiak
Island, a 543 dam high over the north Central Bering Sea, and
ridging over British Columbia that extends north to a 530 dam high
over the Eastern Beaufort Sea. At 850 hpa...A few patches of
temperatures around zero this afternoon, but cooling trend has
started and temperatures across the forecast area will range
from -2C to -15C by Thursday morning. The -10C isotherm will push
east to lie from Point Barrow to Arctic Village to Tanana to
Bethel by Thursday afternoon, and by Friday afternoon the whole
forecast area will be below -10C. The -20C will push east over the
Arctic Plains and Coast Friday and Saturday.

Surface...Broad area of low pressure over mainland Alaska. A 993
mb low has moved over Allakaket with a 993 mb low over Kotzebue,
a 994 mb low over Umiat, and a 987 mb low over Kodiak Island this
afternoon. The lows in the northern part of the state will combine
with a 995 mb low moving over Point Lay by Thursday morning,
while the low over Kodiak will remain quasi stationary. Weak high
pressure will build over the Upper Tanana Valley tonight with a
1002 mb high over the Yukon Territory and ridging over Chukotka
will build east and merge with ridging over the Eastern Bering
Sea. By Thursday afternoon the troughing over the Chukchi Sea and
Arctic Coast will start lifting northeast as high pressure over
the Chukotsk Peninsula pushes east over the Brooks Range and
Arctic Coast as well as the Western Interior. A 998 mb low that
develop over the Middle Koyukuk Basin will be pushed east as the
ridging builds in and a trough that extends south to the low over
Kodiak will move east across the Central and Eastern Interior.
high pressure continues to push east on Friday with the the trough
moving over the Southeast Interior as the low stalls over the
Upper Yukon Valley. As the high pressure builds east a 1031 mb
high moves to the Bering Strait and the troughing persists over
the Upper Yukon Valley and Flats with a strong pressure gradient
developing across the Central and Eastern Brooks Range Thursday
night. A 1024 mb high will develop over the Lookout Ridge on the
Arctic Plain Friday enhancing the gradient over the Range, and
over the Arctic Coast as the gradient gets pinched by the low
lifting northeast.

Arctic Coast and Brooks Range...Low moving to the Northwest Coast
and merging into the troughing over the area. Some light snow
across the area, but mainly west of Nuiqsut. 1 to 3 inches of snow
expected west of Anaktuvuk Pass through Thursday afternoon. High
pressure will be building east across the area Thursday high with
strong winds developing over the Chukchi Sea and moving northeast
over the Northwest Coast Thursday and Friday. Winds increasing to
25 to 40 mph and gusty as the strongest winds move across the
area. Strong gusty winds developing in the Eastern Brooks Range as
well with gusts to around 45 mph near the passes and in channeled
areas. Temperatures will be cooling significantly over the next
few days with lows in the -15 to -30 range by Saturday morning
with colder temperatures to start the week.

West Coast and Western Interior...High pressure building across
the area with much colder temperatures moving into the area. Some
clouds lingering around even as the high pressure builds in, and
that may keep a few areas a bit warmer. Temperatures will be
falling to -10 to -30 by Saturday morning. Some snow this evening
and overnight will taper off from the south as the low moves to
the Northwest Arctic Coast. Snowfall amounts in the 2 to 4 inch
range with the heaviest amounts from Ambler north.

Central and Eastern Interior...High pressure building into the
area, but a weak low developing over the Yukon Flats will drag a
weak trough east across the area that will bring some light snow
to most of the area. Snowfall amounts will generally be pretty
light. Patchy dense fog is a concern with the warmer air over the
cold surfaces, but temperatures will be falling so expect the fog
potential will continue to decrease. Will not be surprised if we
see some 1/2 mile patchy fog overnight. Temperatures will be
falling the remainder of the week with lows -5 to -20 by Saturday
morning, and it still looks like much colder temperatures early
next week. Winds will be light and variable.

&&

Coastal Hazards for days 3 and 4...None.

&&

Extended Forecast for days 4 to 7...Better run to run agreement
in the solutions the last couple days, so will only be making
minor changes to the extended periods. Colder still looks good,
the question will be how cloudy.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Winter Weather Advisory for AKZ216-AKZ217-AKZ218-AKZ219.

Heavy Freezing Spray Warning for PKZ210.

Small Craft Advisory for PKZ210.

Brisk Wind Advisory for PKZ215-PKZ220-PKZ225-PKZ230-PKZ235-
PKZ240-PKZ245.

&&

$$

SDB JAN 18



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