marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 1248 PM PST Tue Nov 21 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
The 18z surface analysis indicated a warm front over the far northern Washington offshore waters, with low pressure near 48n138w. A strong cold front was west of the offshore waters extending north to south along 136w.
The 12z models continue to be in good agreement through the short term period through Friday night, but continue to diverge over the weekend. For the short term period, will maintain the gales over portions of the Washington and Oregon waters into early this evening, with winds diminishing below gale later in the evening. Another low will pass northwest of the Washington waters Wednesday with a brief period of gales expected over the outer portion of the northern Washington waters Wednesday afternoon. Then for Thursday into Thursday night, a trough will pass across the Washington and Oregon waters with all the models in reasonable agreement, although the ECMWF is slightly further north compared to the GFS/UKMET/CMC. Will side with the model consensus here and use the GFS which will result in a six to twelve hour period of gales over the Washington/Oregon waters. A brief break is expected Friday and Friday night before the next system affects the area over the weekend. As for the system over the weekend, the models have been extremely erratic the past few days with this system. The GFS a few days ago indicated a strong low moving across the Washington/Oregon and northern California waters, then trended significantly weaker yesterday and last night. The 12z GFS run has again trended much stronger and faster with the this system. The UKMET is less progressive, while the ECMWF is in between, and is also not too different from CMC. With this in mind, will use the ECMWF to populate wind grids beginning 12z Saturday and continue through the end of period. However, confidence is below average given the large changes the past few days with this system. This will result in gales over most of the Washington and Oregon waters and far nothern portion of northern California waters Saturday into early Sunday. Another trough will move across the northern waters Sunday night with a brief period of gales over the Oregon waters.
.Seas...The 18z sea state analysis indicated that both the wavewatch iii and ECMWF wam were both too high with seas over the Washington and Oregon waters by about 3 to 6 feet on average. An extreme example buoy 46089 over the eastern Oregon waters was reporting 12 feet at 20z with the wavewatch forecast 19 feet and the ECMWF wam at 16 feet. The observed seas over the California waters were mostly within a foot of the models. Will lower adjust seas lower over the Washington and Oregon waters for tonight, then will go close to the wavewatch through 12z Saturday. Will then use the ECMWF wam for the remainder of the period.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... .pzz800...inner waters from Cape Flattery to Cape Shoalwater... gale possible Saturday night. .Pzz900...Outer waters from Cape Flattery to Cape Shoalwater... gale Wednesday. Gale possible Saturday night. .Pzz805...Inner waters from Cape Shoalwater to Cape Lookout... gale today. Gale possible Saturday night. .Pzz905...Outer waters from Cape Shoalwater to Cape Lookout... gale today. Gale Thursday. Gale possible Saturday into Saturday night. .Pzz810...Inner waters from Cape Lookout to Florence or... gale today. Gale possible Saturday night. .Pzz910...Outer waters from Cape Lookout to Florence or... gale today. Gale Thursday. Gale possible Saturday. .Pzz815...Inner waters from Florence or to point St. George... gale today. Gale possible Saturday night. Gale possible Sunday night. .Pzz915...Outer waters from Florence or to point St. George... gale today. Gale possible Saturday into Saturday night. Gale possible Sunday night.
.Pz6 California waters... .pzz920...outer waters from point St. George to Point Arena... gale possible Saturday into Saturday night.
.Forecaster kosier. Ocean prediction center.