marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 805 am PDT Thu Jun 20 2019
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
12z surface analysis shows an expansive high pressure area extending from the Gulf of Alaska to a 1032 mb high centered near 48n138w to another high pressure 1031 mb centered W of the northern California waters near 42n139w. This epac high continues to interact with a coastal trough across interior northern and central California and create a strengthened pressure gradient with gale force winds occurring within the inner northern and central California waters. The high is expected to remain nearly stationary through Sunday with the pressure gradient relaxing enough by late Friday night that winds will likely drop below gale force. Thereafter, the high will drift westward as well, with winds diminishing below 30 kt by Monday.
.Seas...12z sea-state analysis indicates an area of 15 to 16 ft seas straddling the coastal and inner offshore northern and central California waters with an area of 12 to 15 ft seas spreading southwestward from the maximum in response to the 30 to 35 kt wind field noted above. Enp wavewatch guidance appears to have a foot or two higher values than that of the ecwave, so current grids remain in better alignment with current conditions.
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For the wind grids, will lean towards the 00z GFS through the end of the forecast period Mon night. GFS has good support from the 00z UKMET and from the 00z ECMWF through the short term.
As has been for the last several days, main weather features over the next few days will continue to be the epac high and its interaction with the coastal trough along northern and central California. Latest ascat pass continues to show area of gales along the northern and central California coast and extending westward into the eastern portions of the adjacent offshore waters. Model guidance continues to be in good agreement with this pattern remaining through Fri, but with the possibility of winds falling below gale force for a brief time during the late morning and into the afternoon hours during the lull in the diurnal cycle. Guidance agrees with gradient relaxing enough for gales to diminish later Fri night and will allow for gales to diminish then. No changes to the headlines are expected at this time with high confidence in the forecast.
For Sat and sun, will favor the slightly stronger GFS over the ECMWF as it has support from the UKMET. Gales are not expected over the offshore waters during this time period, but winds will remain in the 20 to 30 kt range. Pattern is expected to diminish even more Mon and Mon night as a weak area of low pressure moves into the northern offshore waters.
.Seas...For the wave grids, will lean towards the 00z enp wavewatch guidance through the end of the forecast period Mon night. Seas near 15 to 16 ft in the gale area. Do not anticipate seas getting much higher through Fri.
.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 today into Friday night. .Pzz825...Inner waters from Point Arena to Pigeon Point... gale today into Friday night.
.Forecaster Huffman/achorn. Ocean prediction center.