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Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
338 PM akst Sat Feb 16 2019

Discussion...
strong winds and blowing snow continue from the Bering Strait
north this afternoon, with winds and snow diminishing this evening
and overnight. The next storm will start to enter the western
interior early Sunday morning, moving north and east across the
interior, bringing snow, warmer temperatures, and a chance of
freezing rain to portions of the southwest and central interior.
The next storm approaches the y-k Delta early Monday morning, with
snow spreading eastward across the southern half of the interior
during the day Monday.

Aloft, at 500 mb, a broad longwave trough remains over the western
Bering Sea. A low is centered over the Kamchatka peninsula this
afternoon, a low is 100 nm north of Atka, and a shortwave
stretches from the chukotsk peninsula to St Lawrence Island to
Emmonak to Aniak to Kodiak. The low over the Kamchatka peninsula
will slowly move northward tonight, while the low north of Atka
moves northeast to be situated between the pribilofs and Kuskokwim
Bay by Sunday morning. The shortwave over northern Alaska moves
eastward to stretch from Point Hope to Allakaket to Fort Yukon and
south to McCarthy, exiting Alaska Sunday night. A broad shortwave
develops southeast of wrangel island over the Chukchi Sea Monday
morning, extending southeast to the western Beaufort Sea coast and
western Brooks range. The low that was near the Kuskokwim Bay
early Monday morning, moves onshore during the day, lifting to the
northeast and becoming absorbed by the developing shortwave over
the western North Slope and western Brooks range. A closed low
develops north of utqiagvik Monday night within the flow of the
shortwave moving east across the Bering Sea Monday and Monday
night and onshore the West Coast Tuesday. Behind the shortwave,
ridging begins to build in across the Bering and subsequently much
of Mainland Alaska.

Surface...a leeside trough is north of the Brooks range this
afternoon, anchored by a 1015 mb low over Demarcation Point. A
980 mb low is over the chukotsk peninsula. The leeside trough will
weaken tonight, as will the low near Demarcation Point, moving
north of the Arctic coast. The low over the chukotsk peninsula
will weaken to 989 mb as it moves north to be 100 nm west of
wrangel island by early Sunday morning with a broad trough
extending eastward across the chukchi and Beaufort seas. The low
will weaken to 992 mb and be 150 nm northwest of wrangel island by
Sunday afternoon with the weak trough extending east to Banks
Island.

High pressure will build in over the eastern interior with a 1029
mb high developing near Fort Yukon this afternoon. The high will
move northeast of Fort Yukon by Sunday morning, weakening to 1020
mb as it moves northeast to be 100 nm east of Arctic Village, to
be along the alcan border Sunday afternoon, and weakening in place
Sunday night.

A trough of low pressure stretches along the Aleutians this
afternoon, with a 989 mb low 150 nm southwest of Cold Bay. The low
will quickly lift northeast across Bristol Bay Saturday night to
be a 997 mb low centered over the eastern Kuskokwim Bay by early
Sunday morning, continuing north to be a 998 mb low Sunday
afternoon over eastern Norton Sound. The low will continue to move
north Sunday night weakening to 999 mb as it moves across the
western Brooks range. This low will in turn deepen the leeside
trough developing north of the Brooks range and result in a broad
trough north of the Brooks range. The trough will lift north
during the day Monday with two main low centers Monday afternoon,
a 996 mb low centered over utqiagvik, and a 998 mb low in
MacKenzie Bay. The 999 mb low over utqiagvik will move northeast
Monday night to be a 999 mb low located 150 nm northeast of
utqiagvik Tuesday morning, while the 998 mb low over MacKenzie Bay
weakens to 1000 mb as it moves northeast to be near cape
dalhousie.

Sunday afternoon, a 972 mb low enters the southern Bering Sea to
be 100 nm north of Atka. The low will weaken to 981 mb by early
Monday morning as it moves northeast to be 75 nm northeast of St
Paul island, continuing to quickly move east to be a 993 mb low
centered 100 nm northeast of Dillingham Monday afternoon.

Models...12z model suite initialized well against the 12z radiosonde observations
and fair against the 12z surface obs. 12z surface obs showed a
tighter gradient between Ambler and Kotzebue this morning than
what models initialized with, resulting in stronger winds being
realized for that area than what model guidance suggested. Models
are in good agreement with the overall synoptic pattern through
the short term. At the mesoscale level though, differences become
readily apparent by Monday night with the low that moves across
the western Beaufort Sea coast and the western Brooks range. European model (ecmwf)
deepens the low and moves it south of utqiagvik, while NAM and GFS
move it over the Beaufort. Nudged towards the GFS/NAM solution for
this forecast package.

North Slope and Brooks range: fairly quiet conditions expected the
next couple of days. A weather front continues to move east across
the North Slope this afternoon, with snow tapering off in the wake
and winds in the Brooks range diminishing. Winds ramp up again in
the Brooks range passes Sunday night and Monday with the approach
of the next weather front. Southerly winds tonight and Sunday,
will become westerly on Monday, allowing for temperatures to warm
up, with highs generally well above zero Sunday and Monday.

West Coast and western interior: conditions will continue to
slowly improve this evening and overnight as winds diminish and
snow tapers off from the Bering Strait north. The next storm
system will move into the western interior by early Sunday
morning, moving north northeast across the region during the day,
bringing heavy snow and the chance for freezing rain (primarily
from Marshall east and north to galena). Snowfall amounts will be
in the 2 to 4 inch range across much of the area, with higher
amounts of 4 to 7 inches stretching from Russian Mission northeast
to Ruby, as well as for a pocket of 4 to 6 inches north of
Shungnak. As that system is departing to the north northeast, the
next system approaches the y-k Delta by Monday morning, moving
eastward during the day, with the highest snow chances south of
the Seward Peninsula. Snowfall totals for Monday are in the 1 to 3
inch range. Issued a Winter Weather Advisory for zone 217 for heavy
snow, primarily north of Shungnak.

Central and eastern interior: snowfall associated with a weather
front moving across the eastern interior will taper off quickly
this afternoon and evening. On Sunday, ahead of the next weather
front, winds in the Alaska Range passes will strengthen as the
pressure gradient tightens, with gusts to 50 mph possible in the
eastern Alaska Range. Another round of snow accompanies the next
front Sunday and Sunday night, with snow lingering into Monday as
another front moves across. Periods of heavy snow are possible
and there is a slight chance of freezing rain in zone 221.
Snowfall totals Sunday through Monday will range from 1 to 2
inches fro the far eastern interior to pockets of 4 to 7 inches
from Minto west in zone 221 and in the favored upslope areas of
the southeastern Brooks range. Issued Winter Weather Advisory for
zone 218 for snowfall along and west of the Dalton Highway. In the
eastern Alaska Range, 6 to 10 inches of snow will possible, with
higher amounts west of the Tok cutoff. The combination of gusty
winds and falling snow will lead to areas of blowing snow and
reduced visibility for the eastern Alaska Range. Issued a Winter
Weather Advisory for snow and blowing snow for zone 226, starting
at 3 am Sunday morning.

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

&&

Afg watches/warnings/advisories...
Winter Storm Warning for akz207-akz208-akz209-akz213.

Winter Weather Advisory for akz205-akz206-akz215-akz216-akz217-
akz218-akz219-akz221-akz226-akz227.

Gale Warning for pkz210-pkz215-pkz220-pkz225-pkz230.

Brisk Wind Advisory for pkz200.
&&

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