marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 146 am PST Mon Dec 10 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
00z global model guidance in good agreement into early Thu, with differences noted thereafter. For the wind grids, will lean towards 00z GFS through 12z Thu, then go with the previous grids for continuity after 12z Thu and through Fri, and revert back to the GFS Fri night.
Latest guidance remains in good agreement with timing and strength of frontal system, a warm front followed by a cold front, expected to affect northern offshore waters late today and tonight. Model consensus still showing gale to near gale conditions in the southerly flow ahead of the boundary. GFS/NAM and Canadian along with high resolution arw/nmm/namnest show gales a bit farther S than both the ECMWF and the UKMET. Will continue to have gale warnings for the Washington and northern Oregon zones, which is in agreement with the previous forecast. Confidence in gales remains moderate to high for this system.
Models continue to show a quick surge of cold air advection following behind the cold front late Tue into Tue night with rapid passage of an upper trough and passage of a transient surface ridge. Did boost the GFS 10 meter winds by applying a stability smart toll that boosts the 10 meter winds in unstable areas by 10 percent or so. This will allow for gales to move into the northern offshore waters during this time period, which is in line with the previous forecast. Confidence in gales is moderate at this time.
A second cold front is expected to approach the northern offshore waters Wed, and move into the region Wed night and Thu. Latest model guidance indicate a stronger front with even the more conservative ECMWF/UKMET surface winds showing at least 35 kt, with some models showing winds up to 45 kt possible. Will limit winds to 40 kt for this package. Front stalls near the far se portion of the pz5 waters later Thu, then moves N as a warm front Thu night into Fri as an area of low pressure approaches.
Models continue to diverge with track of the low pressure system, with the ECMWF now slower and GFS faster and leading its ensemble members. Stayed with the previous grids with this package based on a blended 18z GFS/12z ECMWF solution with wpc medium range guidance along similar lines. Confidence is low to moderate with this system as the preferred solution is near the middle of the guidance. This will take the low across the northern offshore waters Thu night into Fri. For the winds, models in general agreement with gales for this system, but again with uncertainty with the track of the system, and will limit winds to 35 kt for now.
Yet another strong cold front is expected to approach the northern offshore waters Fri night, but gales expected to be west of the area by the end of the forecast period.
.Seas...Latest wave guidance within a foot or two of current surface observations across the coastal and offshore waters, even to the N near the Canadian coast where seas were running higher earlier. For the wave grids, will lean towards the 00z enp wavewatch guidance through 12z Thu and again Fri night, in- between use the previous grids, a 50/50 blend of the old 09/12z ECMWF wam and 18z enp Thu through Fri.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... .pzz800...inner waters from Cape Flattery to Cape Shoalwater... gale tonight. Gale Tuesday night. Gale possible Wednesday into Wednesday night. Gale possible Friday. .Pzz900...Outer waters from Cape Flattery to Cape Shoalwater... gale today into Tuesday night. Gale possible Wednesday into Wednesday night. Gale possible Friday. .Pzz805...Inner waters from Cape Shoalwater to Cape Lookout... gale tonight. Gale Tuesday night. Gale possible Wednesday into Wednesday night. Gale possible Thursday night into Friday. .Pzz905...Outer waters from Cape Shoalwater to Cape Lookout... gale tonight into Tuesday night. Gale possible Wednesday into Wednesday night. Gale possible Friday. .Pzz810...Inner waters from Cape Lookout to Florence or... gale tonight. Gale Tuesday night. Gale possible Thursday night into Friday. .Pzz910...Outer waters from Cape Lookout to Florence or... gale Tuesday into Tuesday night. Gale possible Wednesday. Gale possible Thursday night. .Pzz815...Inner waters from Florence or to point St. George... gale possible Thursday night. .Pzz915...Outer waters from Florence or to point St. George... gale Tuesday night. Gale possible Thursday night.
.Pz6 California waters... .pzz820...inner waters from point St. George to Point Arena... gale possible Thursday night.
.Forecaster Bancroft. Ocean prediction center.