Blizzard in Alaska, December 2, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
504 AM AKST Sat Dec 2 2017

.DISCUSSION...
Models...the 00z model suite initialized well against the 00z
surface analysis and verified well against the 06z surface
analysis. Model spread remains good in the short term but rapidly
diverges on system track and strength both the mid range as well
as the long range as the current pattern becomes more blocked with
a high amplitude ridge over the west coast of North America and a
weak longwave trough retreating west over the western Bering Sea.
Continue to favor a blend of ensemble means in the extended
forecast.

Aloft at 500 hpa, a weak ridge over the Gulf of Alaska and
eastern interior of Alaska will build in strength and push both
northward and westward as a high amplitude blocking ridge builds
north from British Columbia and just off the coast of the Pacific
Northwest. A strong shortwave rotating around an upper level low
over the western Bering Sea moves north to be along the south
coast of Alaska Sunday night and over the Alaska Range Monday
morning. Upper level winds increase dramatically over south
central Alaska as well as the Alaska Range Sunday afternoon and
Monday as the shortwave moves north along the west side of the
upper level ridge. Southerly winds at 700 hpa as well as 850 hpa
crossing the Alaksa Range will produce a strong mountain wave
beginning Sunday Afternoon and will continue into Monday
afternoon and possibly longer. Mountain wave breaking along the
northern foothills of the Alaska Range has the potential to
produce strong and damaging winds in excess of 70 mph along and
near the northern Alaska Range foothills beginning Sunday
Afternoon and into Monday. High wind watches have been issued for
these areas. 850 hpa temperatures rise to the zero to 5 above
range over much of the interior south of Fairbanks Monday and
Tuesday.

On the surface expect the warm temperatures aloft to realized at
the surface especially in the hills where temperatures will push
into the 30s. Temperatures in the Alaska Range may approach 40
degrees Monday. Winds are expected to scour out lingering valley
inversions and will help boost temperatures at valley levels into
the 20s to lower 30s Monday and Tuesday over the southern interior.
Another strong shortwave approaches the southern coast by
Thursday morning and Pushes over the Alaska Range Thursday night
and will likely bring another round of strong winds to the Alaska
Range and northern foothills as well as another round of warm
temperatures Thursday and Friday to the southern interior.

A 966 mb low pressure system currently over the western Bering Sea
with attendant frontal system stretching from the low northeast
through the Bering Strait and then southeast over the western
Interior will weaken in place to 970 mb by sunday morning. The
front continues to move to the east and northeast and will rapidly
weaken as the it moves into the central and eastern interior
Sunday. Chinook winds over the Alaska Range and will increase on
Sunday and will limit precipitation south and east of Manley Hot
Spring with only a chance of snow expected in these areas while an
inch or two of snow is expected north and west of Manley Hot
Springs. Snow and blowing snow over the western Brooks Range and
western interior will diminish through the day today and will
diminish over the northwest coast late this evening and Sunday
morning.

A 1035 mb high pressure system near 80N and 160E combined with a
deep low in the Gulf of Alaska will produce gusty east to
southeast winds over interior summits Sunday and Monday as the low
in the Gulf moves slowly north and west over Bristol Bay.

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

&&

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

Winter Weather Advisory for AKZ201-AKZ207-AKZ208-AKZ209-AKZ216-
AKZ217.

Heavy Freezing Spray Warning for PKZ225-PKZ230.

Gale Warning for PKZ230.

Small Craft Advisory for PKZ225.

Brisk Wind Advisory for PKZ215-PKZ220-PKZ235-PKZ240.
&&

CCC DEC 17