Marine Interpretation Message
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099
AGPN40 KWNM 221359
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
659 AM PDT Tue Aug 22 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. The 06z GFS and
NAM remain in very good agreement with the previous 00z models
through the period. The models still indicate a brief period of
gales possible over the far southern Oregon/northern California
coastal waters late Friday and Friday evening, however these
should be short lived as the coastal trough weakens again over
the weekend. Weak cold front currently west of the Washington and
Oregon waters will pass southeast across the area later today
into Thursday while continuing to weaken. Winds will remain well
below gale with this front. The 12z sea state analysis indicated
that observed seas matched up well with the WaveWatch III
forecast values.

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

Weak synoptic systems are still affecting winds and seas over
the forecast waters will remain that way with winds below gale
force threshold through the period. Satellite images continue to
show mostly cloudy skies across the forecast waters with cyclonic
circulation over the south waters. Latest observations including
scatterometer pass show higher winds to 25 kt over the central
waters. At 06Z the NCEP weather map still has high pressure 1026
MB near 35N140W with its ridge extending northeast into the north
waters. Low pressure 1014 MB centered over the western edge of
the southern waters. Pressure gradient is fairly relaxed across
the region and the models GFS/CMC/ECMWFHR/UKMETHR support keeping
a relaxed pressure gradient through most of the forecast period.
The models have initialized well the 06Z surface observations
with just minor differences that do not change the main synoptic
pattern. Will stay with GFS.

Models in the upper levels show a weak cut off low with little
enrgy over the southern region but hig pressure ridge extends
ridge northeast into the north waters. Models agree on pushing
the little ernegy inland leaving behind high pressure and will
remain that way into the extended period.

.SEAS...Seas are relatively higher over the southern waters with
a peak at 9 ft. Seas range between 3 and 6 ft over the northern
and far southeastern waters. NWW3 and ECMWFWAVE have both agreed
well on subsiding seas to below 8 ft across the region most of
the period.


.EXTRATROPICAL STORM SURGE GUIDANCE...n/a.



.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Kosier/Musonda. Ocean Prediction Center.



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