Gale Warning 872, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
454 AM AKST Sat Dec 31 2016

.ANALYSIS AND UPPER LEVELS...

An upper level ridge covers most of the Bering and mainland AK
this morning, with an upper low over Kamchatka. At the surface, a
large ridge is centered over the western Gulf of AK and the AKpen,
while a surface low is over the extreme western Bering. A tight
gradient between these features is bringing storm and gale force
winds to the central and eastern Aleutians, as well as much of the
Bering. A pair of warm moisture streams from the tropics are also
associated with the area of strong winds.

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.MODEL DISCUSSION...

Models are in excellent agreement with respect to features and
wind speeds. The forecast utilizes some NAM and GFS for fine-
tuning.

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.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

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

A quiet weather pattern has arrived for Southcentral for the next
few days, as surface high pressure pushes eastward into the Gulf
of Alaska and becomes established in the southern mainland.
The sounding this morning indicates dry air throughout the lower
atmosphere. This in combination with persistent offshore flow is
helping to keep Southcentral mostly fog free overnight. Light
winds are also keeping temperatures from plummeting too much
overnight under clear skies. It is more uncertain tonight on how
much fog will develop as winds relax further. Models still
indicate conditions will be too dry for widespread fog, but patchy
fog along Cook Inlet and in sheltered valleys is not out of the
question.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Clouds and southeasterly winds will increase today. A weak
disturbance aloft ushers in a new pattern of deep southwesterly
flow as it clips the Kuskokwim Delta today. Light rain, possibly
mixed with snow will spread over the Delta this morning, then
quickly exit the area. This feature will largely miss the
remainder of the mainland. A frontal boundary currently over the
Bering Sea will slowly move ashore Sunday morning and linger
through Monday, solely over the Kuskokwim Delta. Precipitation
will be a mix of rain and snow as southerly flow keeps the near
surface warm, but colder air filters in aloft.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A strong low pressure system off Kamchatka continues to squeeze
the surface pressure gradient over the Bering as a high pressure
anchors over the Gulf. The result is a wide section of gale/storm
force winds over the central Bering sea, concurrent with the
frontal boundary bringing rain to the same area. Normally a
stable southerly flow would prevent the strongest winds from
mixing down from aloft, but the warm front is not particularly
strong in this scenario. The St. Paul 12z/31 sounding shows the
mixed layer to around 2000 ft which should allow for winds in
excess of 70 mph to reach the surface through afternoon, roughly
along a corridor from Nikolski through the Pribilof Islands. The
front will stall out over the eastern Bering Sea late tonight
through Monday, continuing areas of rain and southerly flow.

&&

.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 Southcentral Alaska and
Kodiak Island. Sitting right under the ridge temps 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.
Temps look like they will be warm enough to produce primarily
rain. An upper level short-wave will then track over top of the
ridge Tuesday night advecting precip 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 precip affecting the Aleutians.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIgh Wind Warning 185 195
MARINE...Storms 170 173-176 179 181 185
         Gales 155 165 171 172 177 178 180

&&

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
140 PM AKST SAT DEC 31 2016

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

1129 AM     NON-TSTM WND GST ST. GEORGE              56.61N 169.60W
12/31/2016  M83.00 MPH                          AK   ASOS

            THE ST GEORGE ASOS REPORTED A PEAK WIND GUST OF 83 MPH AT
            1129 AM

&&

LINGRAM