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Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
300 PM akst Mon Nov 11 2019

Discussion...

Synopsis...another round of winter on the way as temperatures will
be falling and a front moving northwest into the interior will be
bringing a significant snow event to the central and eastern
interior. Before that expect winds to be increasing over the
forecast area south of the Brooks range. Travel over the Highway
summits may be impacted as blowing and drifting snow develop. The
increasing chances of snow later in the week will only exacerbate
the problem.

Models...the 11/12z solutions look good for the short term, but
they are really bouncing around in the 48 to 96 hour range
concerning snow and temperatures. Depending on the solution picked
it could be anywhere from 2 to 14 inches of snow in the interior.
The upper Tanana Valley and fortymile country will definitely get
significant snowfall, especially in the upslope areas facing
northeast. Will lean toward the middle of the solutions for now,
but with snow rations going up snow amounts could be much higher.
The solutions did initialize well against the surface analysis
from 11/15z. Solution temperatures are looking much more
reasonable as the cold air pushes southwest into the interior. The
combination of the gradient tightening and cold air advecting
into the area will produce gusty winds, solutions are picking up
on that well. For now will use a blend of solutions for
precipitation with a lean toward the sref. Using mainly the NAM
with some local edits in the upper Tanana Valley and over the
summits in the interior.

Aloft...at 500 hpa...ridging aloft continues with the ridge axis
lying from the alcan border crossing to Lake Minchumina to Cape
Lisburne and northwest to a 550 am high 300 nm northwest of
wrangel island this afternoon. The axis will move to lie from
Seward to Nome to 554 dam high 300 nm northwest of wrangel island
by Tuesday afternoon. Troughing associated with a 502 dam low over
the northern Beaufort Sea continues to dig southwest into
Mainland Alaska as the low moves to just southeast of Banks Island
at 496 dam by Tuesday afternoon. The trough axis will dig
southwest to lie from the low across the northern Yukon territory
and over the south slopes of the eastern Brooks range Tuesday
afternoon. Troughing continues to dig southwest and slides south
over the upper Yukon Flats with a 522 dam closed low developing
over the upper Yukon Flats and moving over the Koyukuk basin by
Wednesday afternoon. Weak ridging will push north over the eastern
Gulf of Alaska Wednesday morning, then is pushed east as a 505
dam low moves to 300 nm south of Sand Point Wednesday afternoon,
and to 300 nm south of Kodiak city by Thursday afternoon as it
weakens to 514 dam and begins to merge with the 522 dam low that
continues to dig southwest across the state and will be over
Bristol Bay at 501 dam. Troughing will persist from northeast to
southwest across the state through Saturday with ridging to the
southeast and northwest. At 850 hpa...the -10c isotherm is
starting to dig southwest over the eastern Arctic coast, while the
0c isotherm has pulled back to the south and lies from Delta
Junction to Buckland. Temperatures will continue to cool over the
forecast areas with the 0c isotherm moving to lie from Denali to
Kaltag to Wales by Tuesday afternoon, while the -10c isotherm
will lie from the alcan border crossing to Livengood to Point Lay,
and the -20c isotherm will lie from Old Crow yt to Atigun Pass to
Wainwright. By Wednesday afternoon the -10c isotherm will lie
along the crest of the Alaska Range to St Michael, and the -20c
isotherm will move to lie from Tok to Livengood to Allakaket to
Howard Pass to Atqasuk then northeast.

Surface...high pressure remains over most of the forecast area
with a 1025 mb high in the Yukon territory and a 1022 mb high in
the upper Yukon Flats. Leeside troughing north of the Alaska Range
has weakened and will continue to weaken tonight. A 1042 mb high
that was in the siberian Arctic has moved to just east of the
dateline near 80n. High pressure is pushing south over the Arctic
coast as the front that moved across the area yesterday drags east
and south over the eastern Brooks range. A 987 mb low south of
the Gulf of Alaska will move to Yakutat and dissipate Tuesday
evening. A 986 mb low 150 nm southwest of St Matthew island will
move west and dissipate in the western Bering Sea. The remnants of
Tropical Storm Halong have moved to 600 nm south of Cold Bay and
will move to 300 nm south of Sand Point by Wednesday afternoon.
The high in the Arctic will move southeast to 300 nm northwest of
Wainwright by Wednesday afternoon and a 1034 mb high will develop
near Old Crow yt, this will tighten the pressure gradient south of
the Brooks range. With the tightened pressure gradient winds will
be increasing for most locations south of the Brooks range.
Thursday afternoon the high pressure over the Arctic will slip
north just a bit as the low in the North Pacific moves to 300 nm
south of Kodiak city at 966 mb. A weather front associated with
the low will move into the southeast interior Tuesday night and
moves northwest into the central and eastern interior through
Thursday.

Arctic coast and Brooks range...weather front continues to drag
over the eastern Arctic coast this evening, but is weakening. With
onshore flow and open water along most of the coast do not expect
the stratus to dissipate, but there could be some breaks. Snow or
flurries tapering off this evening except in the eastern Brooks
range, but no significant accumulation. Winds as mentioned will be
onshore as they swing around from northwest to northeast. Winds
mainly 15 to 25 mph with some gusty conditions locally.

West Coast and western interior...continues to be pretty messy,
but mainly chances of mixed precipitation across the area with
little accumulation. Winds will remain northeast to east as high
pressure pushes south and low pressure remains to the south of the
area. Some increasing chances of snow midweek as cold air starts
moving southwest into the area.

Central and eastern interior...a mix of clouds again tonight with
some clearing. Temperatures cooling as cold air filters in front
the northeast. Winds generally light will be increasing across the
area Tuesday evening and will ramp up over the hills pretty
significantly Wednesday evening. Temperatures will fall pretty
hard starting Wednesday night as some very cold air pushes
southwest into the upper Yukon Flats and the fortymile country. A
wave of moisture will spin into the interior late Wednesday
bringing a multi day overrunning snow event. Expect lots of
blowing snow above treeline, with winds in the lower elevation
areas being rather gusty by interior Alaska standards. Snowfall
will be pretty heavy in the upper Tanana Valley and fortymile
country with snow expected over most of the central and eastern
interior Thursday and Friday. Snowfall amounts are a bit sketchy
at this time as forecast models have wavered over the last couple
days, but potential for significant snowfall is possible as we
continue to evaluate the situation.

&&

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

&&

Extended forecast for days 4 to 7...snow will be tapering off and
temperatures moderating a bit as we move into the weekend. We will
remain in a relatively active pattern with the low to the south
and high pressure to the north.

&&

Afg watches/warnings/advisories...

Heavy freezing spray warning for pkz215-pkz230-pkz240-pkz245.

Gale Warning for pkz225-pkz230.

Small Craft Advisory for pkz200-pkz210-pkz220-pkz235.

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