Blizzard in Alaska, December 30 to 31, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
225 PM AKST Fri Dec 29 2017

.DISCUSSION...
The quiet weather pattern of the last week will transition to an
active pattern especially for the west coast and Bering Strait
beginning Saturday evening and will continue through much of next
week.

Temperatures continue to be the biggest forecast challenge
especially along the cloud edge over the central interior just to
the west of Fairbanks. Locations over the central interior will
experience large temperature swings as the cloud edge meanders
overhead. Generally mostly cloudy skies are found with low
ceiling and Flurries to the west of Manley Hot Springs with
temperatures near zero or single digits below. To the east partly
cloudy skies are noted and temperatures are in the 20s and 30s
below around Fairbanks and the 30s and 40s below over the upper
Tanana Valley and Fortymile Country.

Light snow and low ceilings and fog are found along the north
slope as an upper level low over the western north slope continues
to weaken and drift to the north.

Aloft at 500 mb a 510 dam low currently over the western north
slope will continue to drift to the north and east tonight and
will be located near Point Barrow Saturday morning and 100 nm west
of Banks Island Sunday morning. A broad longwave trough exists
over the eastern Bering Sea and will strengthen and move south to
near the Aleutian Islands Sunday as an upper level ridge builds
back over the Yukon. A series of shortwave troughs will rotate
around the long wave trough over the Bering Sea next week
producing periods of winds and snow over western Alaska, the
Bering Strait and St Lawrence Island. A tight gradient develops
aloft between the upper level low over the Aleutians and the Ridge
over the Yukon and will produce upper level and mid level
southerly winds over much of the central and eastern Alaska. The
upper level winds will produce a lee side trough over the northern
foothills of the Alaska Range and will produce periods of gusty
winds through the Alaska Range passes as well as the northern
foothills of the Alaska Range. A Tanana Valley Jet will form
Saturday night and continue into Sunday from Delta Junction west
to near Nenana and will produce gusty southeast winds. Winds are
expected to remain just below advisory levels.

On the surface a front associated with a 970 mb low over the
central Aleutians will sweep north into the lower YK Delta
Saturday afternoon and over St Lawrence Island and the Bering
Strait Saturday evening. Strong winds and blowing snow are
expected to develop over the Lower YK Delta especially along the
coast Saturday morning and over St Lawrence Island and the Bering
Strait Saturday evening. A Winter Weather Advisory has been
issued for snow and blowing snow as well as for advisory level
wind gusts along the coast for the lower YK Delta beginning
Saturday afternoon. A Winter Storm Watch remains in effect for St
Lawrence Island and the Bering Strait Coast for snow and blowing
snow along with warning level wind gusts beginning Saturday
evening.

The 12z model suite initialized well against the 12 surface
analysis and verified well against the 18z surface analysis. Model
spread remains limited in the short range and is reasonable in the
mid range. Significant timing and strength differences crop up in
the long range.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory for AKZ214.

Winter Storm Watch for AKZ213.

Heavy Freezing Spray Warning for PKZ210-PKZ220-PKZ225.

Small Craft Advisory for PKZ210.

Brisk Wind Advisory for PKZ200.
&&

CCC DEC 17