Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 201322
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
422 AM AKST Mon Nov 20 2017

.DISCUSSION...

Models...For the very short term, around 24 hours, the models are
in good agreement. But, beyond that they differ by up to 300 nm
on location of the low that will start impacting the West Coast by
Tuesday Morning, and that will significantly impact the forecast
confidence starting Monday night. Will be using a blend of the GFS
and Canadian models for now since they will produce stronger
winds across the area, and thus more impact. The 20/00Z solutions
did initialize well against the 20/06Z surface analysis. The
Coastal Flood guidance has been consistent that last few runs.


Aloft...at 500 hpa...A 505 dam low 400 nm north of Point Barrow
will split with a 503 dam low moving northwest to the Dateline,
and a 502 dam low moving southeast into Canada Tuesday. A 510 dam
low south of the Western Gulf of Alaska will move south with a
trough extending north to Yakutat persisting into Wednesday then
moving east. Ridging from a 589 dam high in the north Pacific
extends north over 175W to the Chukotsk Peninsula, then northwest,
and will move to be over Nikolski to Bethel to Cape Lisburne,
then northwest later this evening. The ridge continues to push
east and will be south of the Alaska Peninsula and over Kodiak
Island to Talkeetna to Anaktuvuk Pass to Wainwright, then
northwest by Tuesday morning. By Tuesday evening it will be over
the AlCan Border to Demarcation Point then northwest over the
Arctic. A strong trough is developing over Kamchatka this morning
and will be moving east to the Central Bering Sea by late this
evening. A 502 dam low will develop just north of the Gulf of
Anadyr tonight, and by Tuesday morning will be just south of
Wrangel Island at 500 dam with the trough extending southwest over
the Chukchi Sea Coast to the Bering Strait to Emmonak to Cold
Bay. By late Tuesday evening the low will be 200 nm west of Point
Lay and the trough will lie from Point Lay to Ruby to Seldovia,
and by Wednesday morning the low is still about 200 nm west of
Point Lay with the trough extending over Point Barrow to Arctic
Village to Fairbanks to Valdez and south and moves into the Yukon
Territory early Thursday. At 850 hpa...-20 isotherm lies along the
crest of the Alaska Range to Paxson then to Fort Yukon to
Coldfoot to Wainwright and will slowly move northeast. The -10
isotherm lies from Valdez to Healy to Huslia to Point Hope.

Surface...971 mb low in the Gulf of Alaska will move south and
weaken rapidly, then circle back to the north later in the week
and move over the Southeast Panhandle Wednesday night. A 1030 mb
high over the Arctic Plain with ridging extending southwest to a
1024 mb high over Bethel will move southeast across the Brooks
Range into the Upper Yukon Flats this afternoon with ridging
extending southwest to Bristol Bay. The high moves into the Yukon
Territory by Tuesday morning with ridging extending northwest over
the Upper Yukon Flats, and southwest over the Copper River Basin
and Cook Inlet. Leeside troughing will develop north of the Brooks
and Alaska Ranges and gap winds and the Tanana Valley Jet will
develop as a 986 mb low currently near the Kamchatka Peninsula
moves to the Gulf of Anadyr late this evening at 973 mb, and into
the Central Chukchi Sea by Tuesday afternoon at 970 mb. The
associated weather front will move to St Lawrence Island by this
evening, and the West Coast around midnight. The leading edge of
the front will lie from Wainwright to Ruby to King Salmon by
Tuesday morning, and Tuesday evening it will lie from Nuiqsut to
Fort Yukon to Fairbanks to Seward. The front starts breaking up as
it moves further away from the low and the precipitation will
slowly diminish in the Central and Eastern Interior Wednesday.
Weak high pressure will build in behind the front in advance of
the next system that will move in south of the Bering Strait
Wednesday afternoon/evening.

Arctic Coast and Brooks Range...Stratus will continue to hang
around in the 2000 to 4000 foot range with good visibility and
generally light winds into the afternoon. But, the approaching
storm over Siberia will bring increasing winds this evening to the
Northwest Coast and Western Brooks Range and near blizzard
conditions to the area by Tuesday morning with winds increasing
to the east. Those near Blizzard conditions move east Tuesday
night and Wednesday morning into the Point Barrow area, but do not
work any further east at this time, but expect some increased
winds from Nuiqsut east with blowing snow. Winds speed to the west
will be 30 to 40 mph gusting to 55 mph west of Nuiqsut, with
winds 15 to 25 mph gusting to 40 mph from Nuiqsut east. Brooks
Range passes will see increasing winds tonight with the strongest
winds west of Anaktuvuk Pass gusting to 60 mph, while winds from
Anaktuvuk Pass east will be gusting to around 45 mph. Snow will
generally be light across the area, but the incoming storm will
bring some heavy snow to the Western Brooks Range and parts of the
Northwest Arctic Coast with 4 to 8 inches possible. Expect some
warming of temperatures, especially on the Northwest Arctic Coast.

West Coast and Western Interior...Brief period of clearing this
morning has allowed temperatures to fall significantly with some
areas on the coast reporting single digits. AS the area clouds up
expect those temperatures to rise fairly rapidly later this
morning. Snow will be moving to St Lawrence Island by early
Afternoon and may mix with rain this evening, then all snow
overnight. Snow will move to the coast by evening and will remain
all snow, even in the lower Yukon Delta. Winds increasing this
morning over St Lawrence Island and by afternoon on the West
Coast. Winds increasing to 25 to 40 mph gusting to around 55 mph.
Expect Blizzard conditions over a large portion of the West coast,
but those conditions do not make it east of Norton and Kotzebue
Sounds. Another round of Heavy Snow in the Kobuk and Noatak
Valleys could produce around a foot of snow in some locations with
most areas getting 4 to 9 inches.

Central and Eastern Interior...Relatively quiet the next 24 hours
with mainly clear to Partly Cloudy skies. Clouds will be
increasing early Tuesday morning as they spread west to east
across the area. Expect snow to follow Tuesday afternoon as the
next weather front moves to the area. With the clear skies
temperatures will again bottom out with most areas 20 to 35 below
Tuesday morning. Around Fairbanks temperatures will be in the 15
to 25 below range. Temperatures warming when the clouds move in.
Winds will generally be light in the valleys, but Gap winds in the
Alaska Range will kick up near passes around midnight gusting to
45 mph and diminish Tuesday afternoon. The Tanana Valley Jet will
also kick in late this evening with winds around Delta Junction
gusting to around 40 mph from the east.

&&

Coastal Hazard Potential Days 3 and 4...A storm will move over
the southwest mainland Wednesday evening, then southwest into the
Pacific. Strong north winds will develop over the Chukchi Sea,
Bering Strait, and Eastern Bering Sea. High surf will develop
along the Coast from Cape Espenberg to Diomede, and from Stebbins
to the mouth of the Yukon River.

&&

Extended Forecast days 4 to 7...Guidance for the mid and extended
periods has not been very consistent, but models do indicate a
significant weather system moving to the West Coast Saturday
afternoon with uncertainty with what will happen to it beyond
that.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Winter Storm Watch for AKZ206.

Coastal Flood Watch for AKZ207-AKZ209-AKZ214.

Blizzard Warning for AKZ201-AKZ205-AKZ207-AKZ208-AKZ209-AKZ210-
AKZ211-AKZ213-AKZ217.

Winter Weather Advisory for AKZ212-AKZ214.

Heavy Freezing Spray Warning for PKZ200-PKZ215-PKZ225-PKZ230-
PKZ235.

Gale Warning for PKZ200-PKZ210-PKZ215-PKZ220-PKZ225.

Small Craft Advisory for PKZ230.

&&

$$

SDB NOV 17



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