Blizzard in Alaska, December 10 to 11, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
223 PM AKST Sat Dec 9 2017

.DISCUSSION...
An active southerly flow pattern over Interior Alaska and an
active northerly flow pattern over the Bering Strait and Sea will
highlight the forecast period. Main forecast concerns include
strong winds in the Alaska Range and Saint Lawrence Island, the
potential for blizzard conditions for Saint Lawrence Island and
the Bering Strait, and the potential for low- end warning level
snow accumulations along the southern slopes of the Brooks Range
and over the Koyukuk River Valley Monday and Tuesday. Potential
for freezing rain over the southern Interior, where the strong
southerly Chinook flow will minimize the chances for
precipitation, will be a forecast challenge as the active southerly
flow continues. 09/12Z model solutions are fairly similar
throughout the forecast period regarding the overall pattern
across Alaska. There are some differences between solutions
regarding a low that will move north into the southern Gulf of
Alaska late Sunday night into Monday. 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...Under the upper level ridge today,
fog and stratus have developed in Interior valleys with some
locations reporting low visibility under one mile, but been highly
variable. Expecting fog and stratus to slowly dissipate overnight.
As the ridge shifts north tonight, south winds in the Alaska Range
will increase with gusts up to 65 mph along the Parks Highway
north of Healy and up to 70 mph for Isabel Pass with gusty south
spreading north towards Delta Junction. A wind advisory was issued
for the Parks Highway in zone 225 and south of Birch Lake in zone
223 as well as a high wind warning for Isabel Pass early Sunday into
Sunday evening. It's very likely that the advisories for zones
223 and 225 will either have to be upgraded or extended to
accommodate another round of strong, gusty south winds early
Monday morning into late Monday evening. Several shortwaves will
move over the Interior in the southerly flow and will bring
several rounds of precipitation. The southern Interior should be
downsloped in the chinook flow so that precipitation chances will
be low. If the chinook flow is weaker than anticipated, any
precipitation that falls will likely be freezing rain. To the
north and over the Koyukuk River Valley, 4 to 10 inches of
snowfall is possible late Sunday night through Monday night where
a winter weather watch was issued.

Brooks Range and North Slope...An active southerly pattern will
continue as multiple shortwaves move north in the flow. The first
in the series will move north tonight and bring a round a couple
inches of fresh snowfall to the area through Sunday. A second shortwave
will rotate north Sunday towards the Brooks Range and will be
reinforced by a third, stronger shortwave as it moves north over
Interior Alaska. More moisture will accompany these two shortwaves
and combined with the upslope flow will result in a 24 to 36 hour
period of heavy snow for the southern Brooks Range. Snowfall
accumulations of 4 to 10 inches are possible. Winter Storm Watches
have been issued for the southern Brooks Range from early Monday
morning through Tuesday afternoon. The snow will spread north from
the Brooks Range Monday afternoon and bring 3 to 5 inches of snow
through Tuesday evening. East to northeast winds will increase
through Monday along the Arctic Coast with gusts around 40 mph
possible along the Beaufort Sea coast. These winds combined with
new snow may create a scenario where there will be reduced
visibility that may warrant a winter weather hazard issuance.

West Coast and Western Alaska...Strong northerly flow will develop
over the Chukchi Sea, Bering Strait, and Bering Sea with the
strongest winds expected Sunday evening into Monday morning. A
high wind warning was issued for Saint Lawrence Island from Sunday
morning through Monday evening where north winds are expected to
gust up to 70 mph. As the aforementioned shortwaves rotate north
and west over the western Interior and West Coast, they will bring
the potential for a few inches of snow over the next couple of
days. Over the Bering Strait and Saint Lawrence Island, there is
the potential to 4 to 8 inches of snow Monday morning through
Tuesday morning. This combined with strong, gusty north winds have
the potential for marginal blizzard conditions Monday morning
until the north winds weaken.

Coastal Hazard Potential Days 3 and 4...Strong North winds could
cause freezing spray and high surf at Savoonga Sun night through
Tue.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ223-AKZ225.

Winter Storm Watch for AKZ208-AKZ216-AKZ217-AKZ218-AKZ219.

High Wind Warning for AKZ213-AKZ226.

Heavy Freezing Spray Warning for PKZ210-PKZ220-PKZ225.

Gale Warning for PKZ210-PKZ220.

Small Craft Advisory for PKZ225.

Brisk Wind Advisory for PKZ200.
&&

LTH DEC 17