Small Craft Advisory 1043, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
350 PM AKST Fri Dec 30 2016

.ANALYSIS AND UPPER LEVELS...

The active pattern across south central Alaska will be taking a
turn towards the quiet side this weekend. A strong upper level
wave continues to push across the Copper River Basin and will
move into the Yukon Territory tonight. Meanwhile, a strong ridge
will settle in aloft and stretch from the Gulf of Alaska south
into the Pacific. This ridge will remain in place this weekend and
into early next week. This setup will keep most of the active
weather west and off of the mainland going into next week.

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.MODEL DISCUSSION...

Model guidance seems to be incredibly stable in the short and mid
term. There are no discernible differences noted. Both the East
and West domains utilized mainly NAM guidance to aid in higher
details of terrain.

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.AVIATION...
PANC...The low CIGS may remain a problem overnight as the low
level inversion will trap in the moisture off the Inlet. At this
point enough mixing is anticipated to result in a patchy fog
scenario.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Lingering snow showers over the eastern portions of the Copper
River Basin and Prince William sound continue to quickly taper
off this afternoon. A strong area of high pressure begins to
build over the Southern mainland and pushes the front further
east. Cooler air will continue to filter in behind this front
along with drying and clearing conditions tonight helping
nighttime overnight temperatures to drop. However, south to
southwest flow along the western periphery of the ridge should
cause temperatures to rise slightly along the Cook Inlet and
North Gulf Coast regions over the weekend.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Ridging over the eastern Bering Sea will continue to push in over
southwest Alaska tonight helping to clear out skies and with fog
formation. Saturday, a front will push in from the south helping
to clear out the fog and bring snow to areas around the Kuskokwim
Delta. The front will bring a strong push of warm air that will
transition the snow to a rain and snow mix Saturday afternoon. The
front will also bring strong winds to the coast. The snow and rain
will then push further into southwest Alaska into Sunday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
As the ridging over the eastern Bering Sea pushes off to the east
a front will swing through the Bering Sea from the south. This
front will set up a core of stronger winds Saturday morning in a
corridor from the Pribilof Islands through the area between the
Central and Eastern Aleutians. There is just enough instability to
help mix down higher level winds which will bring warning level
gusts to the Pribilof Islands and Nikolski into Saturday
afternoon. The front will then move off to the east and weaken
while bringing rain to the Eastern Aleutians.

&&

.LONG TERM FORECAST (Days 3 through 7/Sunday night through Friday)...

A strong blocking ridge will be the dominant feature for the first
week of the new year, starting out over the Gulf of Alaska and
eastern Alaska mainland early next week then becoming re-centered
farther west for the latter half of next week. This will result
in a prolonged period of dry weather over south central Alaska
and Kodiak Island. Sitting right under the ridge temperatures will
be near or a bit above normal. Initially, stability does not look
very favorable for fog, but surface based inversions will steepen
with time, so would expect areas of fog to develop early to late
next week.

Southwest Alaska will start out the week on the western periphery
of the upper ridge with a long southerly fetch of warm and moist
air pointed right at the Western Capes and Kuskokwim Delta coast.
Temperatures look like they will be warm enough to produce rain.
An upper level short-wave will then track over top of the ridge
Tuesday night advecting precipitation inland across interior
southwest Alaska and into the interior. Ridging will rapidly
build in behind the short-wave which will finally dry out the
region.

Meanwhile, an active storm track will persist out west from the
North Pacific to the far western Bering Sea with a steady dose of
gale to storm force winds and precipitation affecting the Aleutians.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

SYNOPSIS AND MODEL DISCUSSION...SS
SOUTHCENTRAL ALASKA...TP
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...JA