marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 739 PM PDT Wed Aug 23 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
At 00z, a cold front extended from the southwest Oregon coast across the far northern pz6 waters. A 1840z ascat-b pass depicted northerly winds to 25 kt over the coastal waters off northern California, while winds over the offshore zones remained in the 15 to 20 kt range. No notable changes with this evening update as the 18z GFS came in very close to the preferred 12z GFS solution used for the inherited grids. Still do not anticipate any gales within our offshore zones through Monday night. Most guidance continues to support gales over the coastal waters west of Point Saint George on Friday evening.
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The 18z surface analysis indicated a weak cold front across the Washington and Oregon offshore waters with a weak trough along the California coast. An ascat pass from 1746z indicated the strongest winds, around 20 kt over the northern and central California waters.
The 12z models remain in good agreement through most of the forecast period, with some differences showing up by early next week. During the short term period, the cold front will move slowly southeast tonight through Thursday across the northern and central California waters before dissipating over the central California waters Thursday night. Winds with this front will remain well below gale. Meanwhile, the trough will strengthen along the northern California coast Thursday into Saturday. This will result in mainly diurnal gales confined to the far southern Oregon and northern California coastal waters Friday night. Over the offshore waters the winds will remain below gale. The trough will then weaken again Sunday through Monday night with no gales expected. Then looking ahead to Sunday night through Monday night, all of the models indicate a low pressure moving into the Gulf of Alaska, while ridge remains in place over and west of the offshore waters. The GFS and UKMET are in decent agreement with the intensity of the low, while the ECMWF and CMC are quite a bit stronger. Regardless of which model is more accurate, the impact on the offshore and coastal waters will be minimal. Plan on using the GFS 10m winds to populate wind grids through the period. Prefer the GFS/UKMET for the day 5 period at this time as it is slower to break ridge down.
.Seas...The 18z sea state analysis indicated that observed seas continue to be within a foot of the wavewatch iii forecast values. Will use the wavewatch iii to populate wave grids through the period as differences between ECMWF wam are minimal.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... None.
.Forecaster reinhart/kosier. Ocean prediction center.