AGPN40 KWNM 160330 CCA
MIMPAC

Marine Weather Discussion for N Pacific Ocean...CORRECTED
NWS Ocean Prediction Center Washington DC
830 PM PDT Wed Aug 15 2018

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

A High pressure ridge W of the offshore waters this evening will
be strengthening to the W of the nrn and central areas through
early Sat, then persist through Mon night while gradually
becoming weaker. Coastal trof along nrn CA will gradually
intensify from Thu night into Fri, then persist over this area
into Sun and become weaker into Mon. Strongest winds were along
the inner waters of the WA waters where winds were to 20 kt and
should increase to 25 kt overnight into Thu. As a coastal trof
develops along nrn CA late on Thu into Thu night winds increase to
at least 25 kt along the inner waters of the OR/nrn CA waters and
further increase later Fri night into Sat. For the updated
forecast will not be making any changes with prior grids looking
reasonable across the offshore areas.

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

Per the 18z NCEP surface analysis a high pressure ridge was
located over the offshore PZ5 and PZ6 waters. The latest ASCAT
high resolution data revealed 10-20 kt winds over the PZ5 waters
with the higher winds located in the northwest half of the
waters. 5-15 kt winds were noted over the northern and southern
PZ6 waters.

The 12z guidance continued to maintain good agreement over the
period with the only real differences being noted by day 5 being
the strength of the high pressure ridge overhead. While this
difference on day 5 wasn't huge, felt it was reasonable to allow
the prior grids to remain in for day 5 while the rest of the
forecast period consisted of using the 12z GFS winds. High
pressure ridging continues to be the dominate feature over the
forecast period. A low pressure trough is still expected to
strengthen along the northern California coast late Friday and
expand northward along the Oregon and Washington coasts into
overnight Sunday into Monday, before weakening. Guidance is in
agreement in winds increasing over parts of the southeast PZ5 and
northern PZ6 waters beginning later Friday in response to the
strengthening gradient between the high pressure ridge and low
pressure trough with winds easing a bit overnight Sunday into
Monday. Still anticipate any gales to remain confined to the
adjacent WFO coastal waters east of the northern PZ6 waters but
as has been the case the last several days we will continue to
monitor the trends in subsequent model cycles.

.SEAS...Favored the 12z NWW3 through Monday 00z, allowing the
prior grids to remain in afterwards


.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
None.

.PZ6 California Waters...
None.

$$

.Forecaster Rowland/Holley. Ocean Prediction Center.