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205
AGPN40 KWNM 251434
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
734 AM PDT Sun Jun 25 2017

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

The 12Z preliminary OPC-NCEP surface analysis indicated weak low
pressure areas over the eastern North Pacific Ocean this morning
with one center over the northeast Oregon offshore waters,
another west of the southern California offshore waters and a
third over the eastern Gulf of Alaska, well northwest of the
Washington offshore waters. These weak lows are forecast to
dissipate over the next 24 hours or so. For the morning update
the only changes will be to adjust the ongoing forecast to fit
current conditions noted just prior to forecast issuance, and to
fit nearby coastal and TAFB forecasts a little better.

As far as seas heights are concerned, again the only adjustments
will be to fit the previous forecast to current conditions and
adjacent coastal WFO and TAFB forecasts over the next few days.
Sea heights are running a foot or so above the previous forecast
mainly over southern California waters per the latest
observations and altimeter passes. Sea heights range from 8 to 9
feet or so over parts of the southern California waters, to 4 to
6 feet from northern California northward to the Washington
waters per the latest observations, and the 12Z RP1 OPC sea
state analysis graphic.

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

The ASCAT pass from 06Z shows mainly light winds across much of
the California offshore waters, except the far SE portion which
still has winds 20-25 kt South of point Conception. Further North
over the PZ5 waters winds are mainly out of the N at 15-20 kt,
except for southeastern Oregon waters where light winds prevail.
An altimeter pass from 04Z indicates seas are generally 7 ft or
less over much of the offshore waters. The 00Z global models
continue to be in excellent agreement during the upcoming week.
There is a very minor difference later in the forecast period
between the GFS and the European models. The GFS is slightly
faster with a frontal passage across the Washington and Oregon
waters than the ECMWF, which holds the ridge over the region
longer. This difference is very minor however as the winds remain
light. I will populate the wind grids using the 10M GFS through
06Z Thursday, then transition to the ECMWF for the remainder of
the forecast period.

Seas...Both the ENP and WAM offer similar solutions over the next
7 days, and both appear reasonable. I will populate the wave
grids to match the wind grids. During the period I am using the
GFS I will use the corresponding ENP, and the same goes with the
WAM.

Extratropical Storm Surge Guidance: n/a.


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Mills/Shaw. Ocean Prediction Center.



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