marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 117 PM PDT Thu Apr 19 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
12z global models in good agreement through the forecast period. For the wind grids, will lean towards the 12z GFS for most of this forecast, with a slight deviation towards the 12z ECMWF beginning Mon night.
High pressure will set up northwest of the pz6 waters tonight and Fri and interacts with a coastal trough along California. Latest model guidance continues to suggest Max winds in the 25 kt range for this event, and will keep winds to 25 kt in the forecast. Ridge weakens Fri night as a cold front approaches the northern waters.
Models in good agreement with strength and track of the front, with Max winds of 30 kt in the southerly flow ahead of the front over pz5 waters late Fri into Fri night, and continue with 30 kt winds in the westerly flow behind the front Fri night. See no reason to deviate from the model with this system, and will keep winds to 30 kt in the forecast.
Strong ridge builds to the northwest Sat and Sat night and interacts with a coastal trough along northern and central California. 10m winds from the GFS/ECMWF/do show gale conditions, but limit them to the coastal waters Sat night into Sun night. Believe highest chances of gales will be in the coastal waters near point St George as the high keeps the tightest gradient near the coast, but can not rule out the possibility of gales extending into the adjacent offshore waters. Looks like the best chance of a gale entering into the offshore waters would be Sat night as models showing a 1034 mb high just to the northwest. So will continue with a small area of gales in the offshore waters off northern California for Sat night, but confidence is Low. Ridge slowly weakens sun through Mon night.
Another cold front is expected to approach the waters Mon and Mon night, but is expected to dissipate before moving into the offshore waters as it hits the ridge. High pressure expected to rebuild Tue and Tue night, as the coastal trough intensifies. No gales expected with this system at this time, but will need to be monitored.
.Seas...Wave guidance within a foot or two of current observations. For the wave grids, will lean towards the 12z enp through 18z sun, then move more towards the 12z ecmwfwave thereafter.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... .pzz820...inner waters from point St. George to Point Arena... gale possible Saturday night.
.Forecaster achorn. Ocean prediction center.