marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 753 PM PDT Wed may 24 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
The most recent ascat pass from 19z shows gale winds across the inner offshore waters along the northern California coast, extending into the far se portion of the Oregon waters. A swath of 30 kt winds also is shown extending along the southern coast of Vancouver Island into the far NE portion of the Washington waters. The GFS was forecasting winds to increase since that pass and there could be gales occurring there now. At this time I don't plan on making any changes to the current grids or associated text forecast.
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The gale warnings over the central waters will continue through early Thursday. Latest satellite images still show anticyclonic circulation west of the northern waters while low clouds cover the southern waters. The latest observations including scatterometer pass about 1730z show maximum winds in gale force range over the central waters. At 1800z the NCEP map still has a broad high pressure with several centers over the eastern and central Pacific Ocean. Inland low pressure 1007 mb over northern California has a cold front stretching southwest across the southern waters with its trough extending northwest into Oregon coast. Pressure gradient over the central region is tight but well relaxed elsewhere. Farther west is area are low pressure with first center 1012 mb and second 1014 in the Sea of Okhotsk. The second low will move into the Bering Sea and develop gale force winds in its southern sector in the short term.
In the upper levels the models GFS/CMC/ukmethr/ecmwfhr have indicated a cut off low with some energy just south of the upper level ridge that expands north with ridge axis along 145w longitude. There is some remnant energy from a weakening upper level trough west of the central waters. In the short term the models agree on maintaining the upper level high pressure to the west but weak, with its ridge axis moving east into the forecast region and that will slacken the pressure gradient over the central waters. The ridge axis will persist thereafter through the forecast period.
The models CMC/GFS/ecmwfhr/ukmethr/NOGAPS have initialized well the 18z surface observations. The models have also continue with a general agreement in the short term to weaken the high pressure west of the region which will result in a relaxed pressure gradient over the central waters. Will stay with GFS for the winds with just minor adjustments especially in areas with higher winds.
.Seas...The seas are small over the southern forecast waters ranging between 3 and 6 ft. Seas range between 6 and 15 ft over the north waters. Largest seas with peak at 20 ft are over the central waters. Ecmwfwave and nww3 wave models have initialized well the 18z observed seas pattern but in areas with maximum winds the seas are within 2 ft less than the observations. Will switch to nww3 in this forecast issuance but modify it slightly to match the ecmwfwave areal coverage especially seas in areas of higher winds.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... .pzz800...inner waters from Cape Flattery to Cape Shoalwater... gale tonight. .Pzz815...Inner waters from Florence or to point St. George... gale tonight.
.Pz6 California waters... .pzz820...inner waters from point St. George to Point Arena... gale tonight into Thursday. .Pzz920...Outer waters from point St. George to Point Arena... gale tonight.
.Forecaster Shaw/musonda. Ocean prediction center.