Blizzard in Alaska, December 11 to 12, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
245 PM AKST Sun Dec 10 2017

.DISCUSSION...
Active, southerly flow pattern continues across Northern Alaska
with a long wave trough over the Bering Sea and eastern Siberia
and a ridge to the east over Western Canada. Main forecast
highlights include winter weather hazards across the forecast area
over the next couple of days as well as strong southerly winds in
and along the north side of the Alaska Range through tomorrow
evening. The challenging aspect to this forecast package is the
potential for precipitation in the downslope flow over the
southern Interior. There is a low chance for precipitation, but if
any falls it will likely be a mix of freezing rain and snow. The
10/12Z deterministic model guidance is in good agreement with the
overall synoptic pattern throughout the forecast period, with some
differences in regards to the timing of the individual shortwaves
within the southerly flow. Warmer than normal temperatures will
continue throughout the forecast period south of the Brooks Range
with the models hinting at a cooling trend late next week into
next weekend.

Eastern and Central Interior...Winter Storm Warning for zones 218
and 219 and High Wind Warnings for the Alaska Range will be the
main forecast concerns through late Tuesday. Decided to issue a
High Wind Warning for zone 224 for along the Alaska Highway
between Dot Lake and Tanacross starting this evening. Strong
southerly winds in the Alaska Range will weaken slightly through
early evening, then ramp back up late this evening into tonight
with forecast southerly winds a bit stronger around 80 to 85 mph.
In the flats and along the Richardson Highway south of Delta
Junction, south winds will gust to 70 mph. Strong downslope flow
over the southern Interior will keep precipitation chances low
through Tuesday evening, but during the brief lull in the chinook
this evening there could be a chance for a light mix of freezing
rain and snow. Over the Upper Koyukuk Valley and southeastern
Brooks Range, snow will develop overnight tonight and become
heavy at times. Reduced visibility around one half mile in
blowing snow along the summits of the Dalton Highway in zone 219.
Should see snow taper off late Tuesday morning.

West Coast and Western Interior...Blowing snow, snow, and strong
winds will be the main forecast concerns. Have not changed details
with inherited winter weather hazards, but have added a pair of
winter weather hazards for snow and freezing rain for zones 215
and 227 as well as a high wind warning for zone 227 near the
Alaska Range. Strong northerly winds will continue to increase
over the Bering Sea and Saint Lawrence Island as well the Chukchi
Sea Coast north of Kivalina and combined with new and falling
snow will create near blizzard conditions through late Monday.
Heavy snow will develop overnight tonight and will continue
through Tuesday afternoon resulting in 6 to 12 inches in zone 217,
3 to 6 inches in zones 207 and 208, 3 to 7 inches in zones 215
and 216, and up to 4 inches in zone 227. Warm air aloft will move
overhead tomorrow for zones 215, 216, and 227 (mainly near
McGrath), creating a scenario where freezing rain is likely. Could
see up to one tenth of an inch of ice accumulation. The strong
northerly winds combined with cold temperatures north of Saint
Lawrence Island will cause freezing spray to be blown over the
north shore of the island through Monday night.

North Slope and Brooks Range...Winter Weather Advisories for snow
and blowing snow along the Arctic Coast early Monday through
Tuesday afternoon. Snow will develop over the Brooks Range tonight
and spread north to the Arctic Coast by early tomorrow morning.
From Barrow west could see 4 to 6 inches with up to 4 inches to
the east and lesser amounts of 2 to 3 inches inland. Falling snow
combined with strong easterly flow will create low visibility in
blowing snow over the next couple of days. May see blizzard
conditions develop Wednesday and Thursday along the Beaufort Sea
Coast as easterly winds increase to around 30 to 40 mph. Will
have to monitor to see if action needs to be taken for a winter
weather hazard.

Coastal Hazard Potential Days 3 and 4...None.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Wind Warning for AKZ223-AKZ224-AKZ225-AKZ226-AKZ227.

Winter Storm Warning for AKZ213-AKZ217-AKZ218-AKZ219.

Winter Weather Advisory for AKZ201-AKZ202-AKZ203-AKZ204-AKZ207-
AKZ208-AKZ215-AKZ216-AKZ227.

Heavy Freezing Spray Warning for PKZ210-PKZ220.

Gale Warning for PKZ210-PKZ220-PKZ225-PKZ230.

Brisk Wind Advisory for PKZ200-PKZ235-PKZ240-PKZ245.
&&

LTH DEC 17