Heavy Snow in Alaska, February 24 to 26, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
223 PM AKST Thu Feb 23 2017

.DISCUSSION...

Models...Run to run continuity is quite good and they initialized
well against the 23/18Z surface analysis. Better agreement in the
extended periods so using a evenly wighted blend should work
well. For the short term not going to change much. Will lean a bit
toward the SREF to make the probability of precipitation numbers
a bit more reasonable. Otherwise, will go with an even blend of
the outputs.

Aloft...At 500 hpa...Ridge axis lies over 150W this afternoon and
will continue to rotate to the east around the 576 dam high in the
northeast Pacific. The axis will be east of the state by Friday
morning and the ridge will start to flatten as a series of
shortwaves moves northeast, then east over the top of the ridge.
A couple shortwaves will move east across the state overnight
through Friday morning and timing them will be difficult but they
will be east of the state by noon Friday. A significant shortwave
will move over the west coast Friday morning and over the Western
Interior Friday afternoon. The northern half of the shortwave
washes out, while the southern half moves southeast into the Gulf
of Alaska. Another strong shortwave will move to the west coast
Saturday morning then move across the state through Sunday
morning. The zonal flow accompanying the shortwave will allow for
good moisture flow into the forecast area at all levels. At 850
hpa...Some spotty areas from Fairbanks south of near zero
temperatures moving through the area this evening, then cooling
across the area.

Surface...A 1040 mb high over the Yukon Territory will move east.
Leeside troughing to the north of the Brooks and Alaska Ranges
will become more enhanced this evening as a 997 mb low develops in
the Bering Strait and moves into the Chukchi Sea. 972 mb low in
the Western Bering Sea will move to the north central Bering
Sea by Friday morning as the low in the Chukchi Sea moves over the
Arctic plain south of Barrow. The Bering low moves east across
the Bering Strait Friday evening as the low in the arctic plain
moves east into Canada. The surface ridge flattens out over the
interior and this will bring zonal flow to the forecast area. A
970 mb low will move into the western Bering Sea Friday night and
move to the Gulf of Anadyr by Saturday afternoon. The associated
weather front will reach the west coast early Saturday morning and
move into the interior Saturday afternoon.

Arctic Coast and Brooks Range...Snow, wind, and blowing snow will
be followed by wind, snow and blowing snow through early Sunday.
The heaviest snowfall occur over the next 24 hours with 2 to 7
inches possible. The heaviest snow is currently expected over the
plains. In addition, snowfall of 1 to 3 inches on Friday and
Saturday nights can be expected as well. Expect gusty winds
tonight across the area as the first weather front moves through
the area. Northeast winds of 15 to 25 mph with gusts around 40 mph
will create near blizzard and whiteout conditions. Travel should
be delayed if at all possible until this storm moves through the
area and conditions improve Sunday. Temperatures will warm a bit
this evening then cool through the weekend.

West Coast and Western Interior...More snow on the way if it is
not already falling. The heaviest snowfall with the second punch
will be over the southern Seward Peninsula with 2 to 7 inches of
additional snowfall, the northern Nulato Hills with 3 to 8 inches,
and the south slopes of the western Brooks Range where snowfall
the next 24 hours will range from 5 to 17 inches. If that is not
enough snow, wait until Friday night when those areas are expected
to get another 8 to 20 inches of snow. Yet a third round can be
expected Saturday night, but with only 1 to 5 inches expected.
Will be extending some warnings for the heavy snow, and will need
to look at issuing some warnings for Friday night in a couple
zones.

Central and Eastern Interior...Heaviest snow tonight will be up to
10 inches in the middle and upper Koyukuk River valley in zone
219, and up to 7 inches west of Chandalar Lake in zone 218. For
the Fairbanks area, and most of the remainder of the area expect
1 to 4 inches overnight. Another shot of snow Friday night through
Saturday afternoon will bring will bring 3 to 8 inches of snow to
interior locations, and yet another Saturday night into Sunday
will bring an additional 2 to 5 inches. Temperatures a bit warmer
tonight, then cooling slowly into next week. Some strong gusty
winds near the Alaska Range passes with gusts to around 50 mph
tonight, diminishing early Friday.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Wind Advisory for AKZ226.

Winter Storm Warning for AKZ206-AKZ208-AKZ211-AKZ217-AKZ219.

Blizzard Warning for AKZ201-AKZ207-AKZ209-AKZ213.

Winter Weather Advisory for AKZ202-AKZ203-AKZ204-AKZ205-AKZ210-
AKZ212-AKZ216-AKZ218-AKZ220-AKZ221-AKZ222.

Gale Warning for PKZ210-PKZ230-PKZ235.

Brisk Wind Advisory for PKZ200-PKZ215-PKZ220-PKZ225-PKZ240-
PKZ245.

&&

SDB FEB 17