Marine Interpretation Message
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000
AGPN40 KWNM 231358
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
658 AM PDT Mon Oct 23 2017

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

No changes are planned for the morning update with the 06z GFS in
very good agreement with the 00z models. A high pressure ridge
will dominate over the Washington, Oregon and northern California
waters through the period, while trough along the California
coast strengthens the next few days before weakening later
Wednesday trough Friday. The 12z sea state analysis indicated
that observed seas matched up well with the WaveWatch III
forecast values, and do not plan on making any changes to wave
grids.

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

00Z models have come to a pretty good consensus for the forecast
period. The main issue as noted in previous discussions is the
timing of the front expected th enter the waters Tue night into
Wed. The 00Z GFS now has the same timing of the front as the 00Z
ECMWF and also WPC basic weather guidance while 00Z UKMET is a
bit slower and 00Z GEM much slower. Therefore based on recent model
consistency of GFS/ECMWF and the GFS trend toward the ECMWF with
regard to the front will use the 00Z GFS for today through Wed.
After that to take into account small model differences in
gradients in northerly flow over the offshore waters but with 00Z
GFS/ECMWF otherwise close to WPC medium range guidance will use a
50/50 blend of the 00Z 10m GFS/ECMWF for the rest of the
forecast.

Expect a small area of northerly gale force winds in the coastal
waters of northern CA late Wed and Wed night as the ridge builds
in behind the cold front and the inverted CA coastal trough
strengthens; however, will keep the offshore waters winds below
gale with above average confidence. This will need to be
monitored for the upcoming forecasts as gale force winds will be
a possibility.

.SEAS...Will follow similar reasonings for the seas as the winds;
use the 00Z Wavewatch III through Wed and then transition to a 50/50
blend of the 00Z ECMWF WAM/Wavewatch Wed night and through the
remainder of the forecast.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Kosier/Bancroft. Ocean Prediction Center.



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