marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 827 PM PDT Fri Jun 23 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
At this time I dont plan on making any changes to the current grids or associated text forecasts. The ascat pass from 19z indicates maximum winds to 30 kt across northern California into southern Oregon waters.
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Grids: 12z GFS 10m winds, 12z ww3 throughout. Brief discussion with some modifications mentioned below.
Ascat-b overpass at 18z provided sea truth to the ongoing forecast, with all wind retrievals 30 kt or less. Strongest gradient winds in the 25 to 30 kt range were located in the waters adjacent to point St. George and Cape Blanco, extending westward 250 nm covering the waters of inner zones 815 and 820, and the outer zones 915 and 920. Weakening trend will continue this evening and overnight, with winds diminishing below 25 kt by late tomorrow morning.
Over the weekend fairly quiet conditions / weak associated gradients / flat seas forecast as weak coastal trough shifts to the coastal Pacific NW, and high pressure ridging noses into the central waters. Late in the forecast period, Tue into Wed night, all global models signaling another round of strong prevailing northerlies building off the northern CA and southwest or coasts between strengthening coastal low pressure trough and building E Pacific high pressure. As of now strength of gradient suggests possible gales, but only marginal confidence in timing and coverage this far out in the forecast. Will limit winds in the extended period to 30 kt with the afternoon issuance, and allow future shifts and model runs to dictate if or when warning headlines are needed.
Seas: little differences noted when comparing the 12z wam and ww3, and with deference to the GFS in the wind grids, have no issues using the ww3 throughout the forecast period.
Extratropical storm surge guidance: N/A.
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... None.
.Forecaster Shaw/Collins. Ocean prediction center.