Heavy Freezing Spray Warning 80, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
436 AM AKST Thu Dec 1 2016

.ANALYSIS AND UPPER LEVELS...
A low that has moved into the northern Gulf is bringing snow to
areas around Southcentral Alaska with the heaviest snow along the
north Gulf coast. However, there is enough warm air for some areas
right along the water to see some rain. Southwest Alaska is seeing
colder temperatures with northerly winds which is bringing wind
chills to near 40 below around the Kuskokwim Delta. Further west,
cold northerly flow dominates most of the Bering and Aleutian
Islands.

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.MODEL DISCUSSION...
The models are in good agreement through the mid term for the main
synoptic features. There are a few placement issues with a low
tracking across the Bering Thursday night into Friday, but these
differences will not result in much of a change for impacts.

&&

.AVIATION...
PANC...Snow will continue throughout the TAF period but will
lighten this afternoon before picking back up this evening. The
biggest uncertainty is with placement of the main snow band this
morning. As it shifts back and forth to the east and west
conditions may change quickly. There is also uncertainty with how
far conditions will drop this evening.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The surface low along the northern Gulf coast will move into the
Kenai Peninsula today. The upper level support for this system
will weaken today and the associated moisture will slowly move
north. A weak deformation band will remain over south central
Alaska between the meridional trough over western Alaska and a
low deepening over the southern Gulf later today. As this low
moves into the eastern Gulf, the deformation band will briefly
strengthen for another decent chance of snow over the Kenai
Peninsula and northward to the Talkeetna Mountains. The
deformation band will then dissipate later on Friday.

A strong outflow pattern will begin on Friday and Friday night.
The Gulf low will settle in just south of Yakutat, while a surface
high builds over southwest Alaska under the upper level trough.
Winds are expected to reach storm force in favored marine areas
as the gradient tightens. Temperatures will begin to drop across
the area. Conditions will also dry out, with the exception of the
Copper River basin where some "wrap-around" moisture could bring
some snow.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

As the low south of the Alaska Peninsula moves northeast to the
Kenai Peninsula this morning, snow showers will come to an end
over Bristol Bay. They will, however, continue along the AK and
Aleutian Ranges even as the Kenai low is absorbed into an
approaching Gulf low later today. The mountain snow showers will
then end Fri afternoon as the merged low moves east.

As the low moves into the Gulf today, before merging with the
Kenai low, the pressure gradient will tighten across the Alaska
Peninsula. This will induce northwest flow through channeled
terrain that will result in storm and hurricane force gusts in
marine areas south of the peninsula through Fri night. A weak
ridge will build over the southwest Fri night through Sat with
cold and dry conditions, except for some snow showers along the
AKpen as a front approaches from the west on Sat.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

A low and associated fronts moving across the central Bering and
Aleutians will spread mainly snow showers across the region. As
the system moves east, these snow showers will reach the eastern
Aleutians Fri into Sat. The next front will be associated with a
Kamchatka low. The front will enter the western Bering and
Aleutians on Fri, with snow changing to rain as it moves to the
eastern Aleutians and Pribilof Islands by Sat night.

&&

.LONG TERM FORECAST (Days 3 through 7)...

As we approach the weekend, high pressure will continue to build
in across mainland alaska, with low pressure remaining in the
Gulf of Alaska. This will help to support strong gusty offshore
flow across much of the Gulf of Alaska, with particularly strong
winds occurring across Kodiak Island, Shelikof Straight, and the
Barren Islands. This will continue to support strong cold air
advection and plummeting temperatures this weekend, with likely
the coldest temperatures of the season so far.

By early next week, a pattern change will begin to bring slightly
warmer temperatures back to the Alaska mainland as a trough begins
to push across the southwest mainland. This will help to bring
more moderate temperatures to the region with widespread clouds
and southerly flow across the southwest mainland. It will also
help to dramatically decrease the pressure gradient between the
mainland and Gulf of Alaska and stop the offshore flow and strong
cold air advection.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Wind Chill Advisory...155.
MARINE...Heavy Freezing Spray...160 180 181.
		 Gales...136 137 138 155 160 165 170 172 178 180.
		 Storms...130 131 132 150.

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DS
LONG TERM...EN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1012 AM AKST THU DEC 01 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1011 AM     SNOW             5 SSE SPENARD           61.13N 149.83W
12/01/2016  M2.8 INCH                           AK   NWS EMPLOYEE

&&

JPW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1026 AM AKST THU DEC 01 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1026 AM     SNOW             WILLOW                  61.74N 150.06W
12/01/2016  M8.3 INCH                           AK   COCORAHS

&&

JPW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
211 PM AKST THU DEC 01 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0209 PM     SNOW             1 E POTTER MARSH        61.05N 149.76W
12/01/2016  M2.7 INCH                           AK   TRAINED SPOTTER

            SPOTTER REPORTED 2.7 INCHES OF STORM TOTAL SNOW
            ACCUMULATION THROUGH 2 PM.

&&

MCLAY