marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 145 am PST Wed Jan 17 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
Low pressure is on track to pass to the west of the region and associated fronts will sweep across the northern and central waters while high pressure ridge will still persist over the southern waters. Pressure gradient will continue to be tight as a series of fronts will pass across the northern and central waters while a relaxed pressure gradient will still be confined to the far southern waters through most of the forecast period. Goes16 rgb geocolor satellite images still show massive clouds, associated with developing low to the west of the waters now 540 nm west of the Oregon waters that is moving northeast. Low level diffluence is still depicted over the southern waters. At 06z, NCEP weather map has high pressure 1025 mb just west of the southern waters that still extends a weak ridge across the southern waters while low pressure has deepened to 967 mb, with hurricane force winds in its southern sector, west of the central waters and its warm front stretches southeast across the Washington and Oregon waters. Another low pressure 977 mb with gale force winds is in the Gulf of Alaska. Farther west is still high pressure 1031 mb due far northwest of the Hawaiian islands near the dateline north of 30n that extends a strong ridge north into the Bering Sea. More low pressure systems are west of the high pressure ridge above. In the short term, low pressure west of the waters will keep deepening as it moves northeast and its associated fronts will move across the waters forcing a tighter pressure gradient that will elevate winds to storm force threshold over the western portion of the north waters while high pressure will remain in the same vicinity and help to keep elevated winds confined to the central and northern waters. Low pressure in the Gulf of Alaska will slowly move northwest as it weakens. In the extended period, a series of high pressure centers will be tracking east and will remain to the south of 40n allowing more active weather north of 40n. As such, a prolonged tight pressure gradient will be maintained by a series of low pressure systems that will pass over the central and northern waters.
Global models GFS/CMC/ecmwfhr/ukmethr have initialized the 00z surface observations with very small variations. However, models have some differences especially on the wind speed and also the areal coverage of the winds in warning threshold. In the short term, GFS and CMC have winds reaching storm force in the waters while ukmethr and ecmwfhr only have winds in the gale force range. Ecmwfhr is the only model among the 4 that has less than hurricane force winds with the low at 00z. GFS and CMC have slightly higher winds than ukmethr. Scatterometer pass at 0624z just missed the region of interest but earlier pass had some 70 kt wind barbs and considering that the system is still developing, winds must be at least in the 70 kt range and so will stay with GFS that has continued to depict a good handle on this system.
.Seas...Seas are still relatively large across the region ranging between 12 and 18 ft with a peak at 20 ft over the Oregon and northern California outer waters and they are building. Currently the peak value is 45 ft near 38n144w. Nww3 and ecmwfwave models continue to fit fairly well the observed seas pattern but there are still small differences on the actual peak values. Nww3 has maintained the match for both peak values over the forecast waters and the high seas with the impending low while ecmwfwave is still underdone by 2 ft over the waters and 3 ft over the high seas. Both wave models have continued to be quite consistent which makes it easier to apply any correction factor depending on the wave model choice. The low will still develop more and seas should keep on building and so will continue with nww3 and will stay close to the prevailing seas grids.
.Extratropical storm surge guidance...Storm surge around 9/10 is expected along the Canada coast and but will be less over the Oregon and Washington coasts with a peak on Thursday.
.Pz5 Washington/Oregon waters... .pzz800...inner waters from Cape Flattery to Cape Shoalwater... gale today into Thursday night. Gale possible Friday night into Saturday. Gale possible Sunday. .Pzz900...Outer waters from Cape Flattery to Cape Shoalwater... gale today. Storm tonight into Thursday. Gale Thursday night. Gale possible Friday into Friday night. Gale possible Sunday. .Pzz805...Inner waters from Cape Shoalwater to Cape Lookout... gale today into Thursday night. Gale possible Saturday into Sunday. .Pzz905...Outer waters from Cape Shoalwater to Cape Lookout... gale today. Storm tonight into Thursday. Gale Thursday night. Gale possible Friday into Saturday. Gale possible Sunday. .Pzz810...Inner waters from Cape Lookout to Florence or... gale today into Thursday. Gale possible Saturday. Storm possible Saturday night. Gale possible Sunday. .Pzz910...Outer waters from Cape Lookout to Florence or... gale today into Thursday night. Gale possible Friday. Gale possible Saturday. .Pzz815...Inner waters from Florence or to point St. George... gale today into tonight. Gale possible Saturday. Storm possible Saturday night. Gale possible Sunday. .Pzz915...Outer waters from Florence or to point St. George... gale today into Thursday night. Gale possible Friday. Gale possible Saturday into Saturday night.
.Pz6 California waters... .pzz820...inner waters from point St. George to Point Arena... gale today. Gale possible Saturday night into Sunday. .Pzz920...Outer waters from point St. George to Point Arena... gale today into tonight. Gale possible Saturday into Sunday. .Pzz825...Inner waters from Point Arena to Pigeon Point... gale possible Sunday into Sunday night. .Pzz925...Outer waters from Point Arena to Pigeon Point... gale possible Sunday.
.Forecaster musonda. Ocean prediction center.