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.
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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.
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... None.
.Forecaster Rowland/Holley. Ocean prediction center.