marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 708 am PDT Fri Oct 19 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
High pressure currently centered west of the northern pz6 waters is combining with a low pressure trof along the California coast to produce northerly winds up to 20 knots off the coast of northern California with the strongest conditions west of Point Arena. Winds up to 20 knots or so will continue across the northeastern pz6 and southeastern pz5 waters into Saturday night and then begin to weaken. One cold front will dissipate west of the pz5 waters Friday, while another cold front will cross the area Monday night into Tuesday. Minimal gales are possible across the far northwestern pz5 waters Monday night in the southerly flow ahead of the front. For wind grids will continue to use the current grids throughout the forecast period. Current warnings look reasonable and few changes should be needed on the next offshore waters forecast.
For wave height grids will also continue to use the current grids throughout the forecast period.
Extratropical storm surge guidance...N/A.
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The 06z surface analysis indicated a high pressure ridge across the offshore waters as well as the Washington and Oregon coastal waters, with a weak trough along the California coast. Strong low pressure was located over the Gulf of Alaska near 54n146w with storm force winds in south quadrant as depicted by ascat pass. Over the offshore and coastal waters, winds were 15 kt or less except a small area of 20 kt was noted over the northern California coastal waters.
The 00z models are in very good agreement during the short term period through about 12z Monday, with differences showing up shortly thereafter and continuing through the extended period. For the short term period, high pressure ridge will remain in place through the weekend and into early Monday which will maintain the light wind regime. Big changes are in store later next Monday into Tuesday night and beyond as the ridge weakens which will allow fronts to begin impacting the Washington and Oregon waters. The models are in decent agreement with the first cold front that will move into the Washington and Oregon waters late Monday afternoon and night, and all continue to indicate a brief period of gales for the outer portion of the northern Washington waters. A weak ridge will build across the area Tuesday and Tuesday night before another strong cold front affects the Washington and Oregon waters the middle of next week. The models are actually reasonably close with the timing of the cold front into the Washington and Oregon waters, though there are big differences with the strength and track of low pressure which passes west of the area. For the wind grids, will use the GFS to populate through the period, except will use ECMWF toward the end of next week to better match up with coastal offices. Confidence with gales next Monday evening is now above average as all the models indicate the gales.
.Seas...The 06z sea state analysis indicated that observed seas continue to match up well with the enp forecast values. Will use the enp to populate wave grids, except will transition to ECMWF wam later next week similar to wind grids.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... .pzz900...outer waters from Cape Flattery to Cape Shoalwater... gale possible Monday night.
.Pz6 California waters... None.
.Forecaster nolt/kosier. Ocean prediction center.