marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 140 am PST Sat Feb 16 2019
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
Low pressure over the northern waters will move east of the region in the near short term then high pressure will strengthen and remain anchored to the west of the region through the rest of the forecast period. Latest NCEP weather map has gale force low pressure analyzed near 45n125w at 06z will continue to move east of the Oregon offshore waters. Latest ascat data about 0450z had gales southwest of the low center and over the coastal Oregon waters west of Cape Blanco. The low will gradually weaken as it moves east away from the waters, but much of the model guidance continues to depict a secondary northerly surge today that will bring northwesterly gales into the outer waters between Florence, or and Point Arena, CA. Therefore, we will maintain gale headlines for these zones today.
Overall, the global model guidance is in good agreement this weekend into early next week. Strong high pressure will persist west of 140w, while a developing coastal trough will result in an enhanced offshore pressure gradient that maintains northerly winds across the forecast area through early next week. The model consensus keeps sustained winds below gale force through Tue night, so no additional headlines appear necessary at this time. GFS is generally favored for winds today through Tue night with minimal model differences noted during this period.
Late in the period, model spread increases as low pressure and an associated frontal system dive southeast from the Gulf of Alaska toward the pz5 waters. The GFS guidance appeared to be an outlier with widespread gales across the pz5 zones Wed/Wed night as the front crosses the region. The ECMWF/CMC/UKMET winds were generally 5-10 kt weaker, although the ECMWF did generate marginal gales over the outer waters Wed night. This system will be monitored for gale potential in the coming days. For now, we will take a conservative approach and use a blend of the cmwf/UKMET winds for Wed/Wed night to keep sustained winds just below gale force until we gain more confidence.
.Seas...Seas are very large with a peak at 30 ft over the western edge of the northern California waters. Otherwise, seas range between 12 and 27 ft over the central waters while they range between 8 and 11 ft over the rest of the region. Wavewatch initialized well based on available buoy observations. With the wave models in relatively good agreement through Tue night, forecast will be based on a blend of the wavewatch with previous grids. For Wed/Wed night, will transition to the ecmwfwave with a reduction applied since forecast winds will be adjusted to be slightly weaker than the operational ECMWF.
.Extratropical storm surge guidance...No significant positive surge events are expected over the next few days.
.Pz5 Washington/Oregon waters... .pzz915...outer waters from Florence or to point St. George... gale today.
.Pz6 California waters... .pzz920...outer waters from point St. George to Point Arena... gale today.
.Forecaster musonda. Ocean prediction center.