marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 826 PM PDT Fri Jul 21 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
Gale Warning headlines over the eastern portion of the central waters will be retained in this issuance as inland low pressure trough strengthens near the California coast. Satellite images show mostly cloudy skies across the region with clearing beginning over the eastern portion. Highest winds at 30 kt have been observed over the southern waters. At 00z the NCEP map has high pressure 1026 mb west of the southern waters with its ridge extending east into the central and southern waters. A warm front across the northern waters extends from low pressure 1002 mb in the Gulf of Alaska. Inland trough extends near California coast from low pressure over Arizona and its combined effect with the ridge has resulted in tighter pressure gradient over the central waters were winds will increase to gale force. The models GFS/CMC/ukmethr/ecmwfhr have been quite consistent with the developing gale force winds and so with moderate to high confidence will keep the gale warnings. The models have a good agreement on few synoptic features that will impact the weather and seas across the forecast waters and so will just continue with GFS. In the short term, high pressure to the west of the waters will shift its center slightly west but will keep strengthening its ridge over the region while the inland trough deepens.
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The latest surface analysis indicates that a high pressure ridge west of the pz6 waters continues to combine with an inland thermal trof to produce northwest winds up to 30 knots across portions of the central and southern pz6 waters. The strongest conditions will remain west of Point Conception through tonight, then begin to weaken Saturday. The strongest conditions will then shift north to off of Point Saint George by late Saturday and Saturday night as the thermal trof strengthens, with gales mainly confined to the coastal waters. By Sunday the gales are still expected to extend into the offshore waters and then continue into Sunday night. Conditions will then weaken later Monday. Farther north, a weak cold front currently approaching the pz5 waters will move across the area later today and tonight. The latest runs of the GFS and ECMWF look to be in reasonable agreement across the eastern Pacific through Wednesday. For wind grids will continue to use the GFS 10m winds throughout. Current warnings look reasonable and few changes should be needed on the next offshore waters forecast.
The nww3 looks reasonable with the seas and will be followed fairly closely during the forecast period.
Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... .pzz815...inner waters from Florence or to point St. George... gale Sunday. Gale possible Sunday night.
.Pz6 California waters... .pzz820...inner waters from point St. George to Point Arena... gale Saturday night into Sunday. Gale possible Sunday night.
.Forecaster musonda/nolt. Ocean prediction center.