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000
AGPN40 KWNM 170210
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
610 PM PST Sat Dec 16 2017

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Pacific N of 30N and E of 150W.

Strong high pressure west of the northern pz6 waters continues to
combine with a low pressure trof along the California coast to
produce north to northwest winds up to 40 knots across portions
of the pz6 waters. These conditions will diminish tonight and
Sunday as the coastal trof begins to weaken. By late Monday
mainly light winds are expected across most of the pz6 waters. A
cold front is still expected to move into the pz6 waters from the
northwest by late Tuesday, then move into the southern pz6 waters
by late Wednesday. Winds behind this front are still expected to
be as high as 30 knots across the offshore waters. Conditions
will then diminish again by Thursday. Farther north, a warm front
will move across the pz5 waters tonight, followed by a cold front
Sunday night. Low pressure will then move across the pz5 waters
Monday night and Tuesday with gale force winds still expected.
For wind grids will continue to use the current grids throughout
the forecast period. Current warnings look reasonable and few
changes should be needed on the next offshore waters forecast.

For wave height grids will also continue to use the current grids
throughout the forecast period.

Extratropical storm surge guidance...n/a.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

Strong high pres remains W of the nrn CA waters early this
afternoon and will gradually becoming weaker tonight and Sun. An
intense coastal trof along CA should begin to weaken later
tonight through Sun. A cold front over the srn CA waters should
pass S of the area tonight. There was an ASCATB pass at around
1722Z over the srn CA waters E of 122W. Strongest winds were to
35 kt along the wrn edge of the pass. Elsewhere there was a ship
observation just W of the central CA with N winds at 35 kt which
was slightly stronger than 30M GFS winds which seems to fit well
with the ASCATB data. Will have winds to 40 kt over the central
and srn CA waters for tonight, and diminishing overnight. A cold
front NW of the WA/OR offshore waters will slowly approach the
waters tonight, then stall while crossing the waters Sun. Model
guidance is in good agreement with low pres developing to the W
and SW of the nrn offshore waters and then moving NE into the WA
waters Mon night while strengthening. Will continue to favor the
GFS which has winds in advance of the cold front strengthening
to gale force. A strong high pres area follows behind the low
pres and cold front late Tue and Tue night. As this occurs a
surge moves S over the WA waters with strongest winds over the
WA and nrn areas of the OR waters. Will cap winds to 40 kt for
now. Winds become subgale over this area late Tue night into Wed
as the strong high pres moves E into the waters by Wed night and
weakens across the waters into Thu and Thu night.

.Seas...Will use the WWIII ENP for seas through the forecast
period. The 12Z ECMWF wam looks similar to the WWIII through 12Z
Tue, but it is lower with seas associated with the surge from the
N. Prefer the GFS and UKMET which are similar with the surge.

.Extratropical storm surge guidance...n/a.


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
.PZZ800...Inner Waters from Cape Flattery to Cape Shoalwater...
     Gale Possible Tuesday night.
.PZZ900...Outer Waters from Cape Flattery to Cape Shoalwater...
     Gale Possible Tuesday night.
.PZZ805...Inner Waters from Cape Shoalwater to Cape Lookout...
     Gale Possible Tuesday into Tuesday night.
.PZZ905...Outer Waters from Cape Shoalwater to Cape Lookout...
     Gale Possible Tuesday night.
.PZZ810...Inner Waters from Cape Lookout to Florence OR...
     Gale Possible Tuesday.
.PZZ910...Outer Waters from Cape Lookout to Florence OR...
     Gale Possible Tuesday.
.PZZ815...Inner Waters from Florence OR to Point St. George...
     Gale Possible Tuesday.

.PZ6 California Waters...
.PZZ820...Inner Waters from Point St. George to Point Arena...
     Gale tonight.
.PZZ825...Inner Waters from Point Arena to Pigeon Point...
     Gale tonight.
.PZZ830...Inner Waters from Pigeon Point to Point Piedras Blancas...
     Gale tonight.
.PZZ930...Outer Waters from Pigeon Point to Point Piedras Blancas...
     Gale tonight.
.PZZ835...Inner Waters from Point Piedras Blancas to Santa Cruz Island, CA...
     Gale tonight.
.PZZ935...Outer Waters from Point Piedras Blancas to Santa Cruz Island, CA...
     Gale tonight.
.PZZ840...Inner Waters from Santa Cruz Island, CA to San Clemente Island, CA...
     Gale tonight.
.PZZ940...Outer Waters from Santa Cruz Island, CA to 120W...
     Gale tonight.

$$

.Forecaster Nolt/Rowland. Ocean Prediction Center.


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