marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 835 PM PDT Fri Aug 17 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
High pressure this evening was centered to the W of the WA/OR waters and persists through Mon before becoming weaker Mon night. A trof over inland areas of CA intensifies near the N coast tonight and persists through Mon before also weakening late Mon and Mon night. At the moment the pressure gradient is strongest along N CA and or coast. Earlier ascat pass had 30 kt in this region and 18z GFS was slightly weaker than data indicated. Model guidance does look good with the winds for tonight through early Mon where strongest gradient will be persistent. For the updated forecast will stay with prior grids which look fine.
Seas...at 00z highest seas to 11 ft were located along the Pt St George near the CA coast where the strongest pressure gradient was. This fits well with both the wwiii and ECMWF wam model guidance which has highest seas through tonight in this region and expands further S along the inner waters of the nrn CA waters Sat.
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Per the 18z NCEP surface analysis a high pressure ridge was located across the opc offshore pz5 and pz6 waters while a low pressure trough was present just inland of the California coast. The latest ascat high resolution data revealed 10-25 kt winds over the pz5 waters, extending down into the northwest pz6 waters. 5-15 kt winds were noted over the southern pz6 waters east of 122w.
Yet again the latest model package, this 12z package, continues to the good agreement seen over the 5 day forecast period, continuing the trend seen all week. Hence will continue using the latest version of the GFS, the 12z run, for this forecast issuance. High pressure ridging continues to be the dominate feature over the offshore waters with low pressure troughing expected to strengthen later today and maintain that strength into Monday before weakening late Monday. Continue to expect winds to remain below gale force over the offshore waters through the period, though winds will remain increased over the pz5 and northern pz6 waters today into Monday in response to the tightening pressure gradient due to the interaction of the high pressure ridge with the strengthening low pressure trough.
.Seas...Favored the 12z nww3 over the forecast period given the choice to favor teh 12z GFS winds over the forecast period.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... None.
.Forecaster Rowland/Holley. Ocean prediction center.