marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 632 am PDT Tue Mar 31 2015
.Forecast discussion: major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
No changes are planned for the morning update. The 06z GFS was very close to the previous 00z run...with the 06z NAM also similar. Previous shift used 00z GFS through Fri night...then transisitioned to blend with ECMWF Sat as differences become larger. This still looks reasonable...and warning headlines also on target. The 12z sea state analysis indicated that observed seas were within a ft of the mww3 forecast values.
----------------------------------------------------------------- Previous discussion...
Short term...a 508z ascat-b pass indicated Max winds nr 20 to 25 kt ovr wtrs off the central calif coast...mainly W and NW of pt Conception...with winds gnrly under 20 kt elsewhere ovr the off wtrs very early this morning. The prelim 06z opc sfc analysis indicated a weakening cold front from the pac NW coast SW ovr NW calif off wtrs with hi pres building E along 35n. A 1034 mb hi pres center is located currently about 775 nm N of Hawaii. As the pres gradient between high pres building E toward the off wtrs and a dvlpg coastal low pres trof strengthens there will be an increasing chance for gales ovr portions of the srn and central calif off wtrs ltr today thru Wed ngt. At this time...the main concern ovr the off wtrs for the next few days will be the increasing threat for N-NW gales dvlpg off the srn and central calif coast by ltr today...then contg tngt into Wed and Wed ngt. Gales appear most lkly ovr the inner wtrs of zones 840 and 835 by ltr today with confdc in these gales occurring somewhat abv average. Gales may spread N to the inner wtrs of zones 830 and 825 Wed ngt. Confdc in these gales occurring is near to slightly below Ave. Conditions are expected to improve somewhat Thu into Thu ngt as the high builds E and NE into srn pz5 wtrs and the coastal low pres trof begins to weaken. The next cold front will slide E into pz5 wtrs Thu ngt. The latest mdl guid suggests that this front will be a little weaker than previously fcst. We will therefore remove gales for parts of the nrn pz5 wtrs for Thu ngt. For the early am package...we will stay close to the 00z GFS 30m winds for the fcst today thru Thu ngt.
Long term...for Fri and Fri ngt the 00z mdl guid remains in pretty decent agreement ovr the off wtrs. We will stay close to the 30m GFS winds for the fcst for Fri and Fri ngt ovr the off wtrs as a result. Winds are fcst to remain sub-gale ovr the off wtrs for Fri and Fri ngt...with any gales holding to the NW of the pz5 wtrs as low pres to the NW of the wtrs slides se and weakens. For Sat and Sat ngt...we will use a 50-50 blend of the 00z GFS and 00z ECMWF mdls. The 00z GFS attempts to bring gales back to the inner wtrs of srn-central calif Sat and Sat ngt...with the 00z ECMWF indicating sub-gale force winds. The blend of the two mdls keeps winds just below gale force for portions of the inner srn and central calif wtrs Sat and Sat ngt...for now.
.Seas...The 00z enp WV watch iii mdl guid appears to have initialized well ovr the off wtrs per the latest rp1 sea state analysis. We will remain close to the 00z enp ww3 mdl output as a result for today thru Fri ngt...and then as we use a 50-50 blend of the GFS and ECMWF as noted abv for winds...we will use a 50-50 blend of the ww3 and ECMWF wam WV guid for fcst sea hts for Sat and Sat ngt...altho trimming back hts ovr NW wash wtrs slightly for Sat and Sat ngt to fit a bit better with our fcst winds at that time.
.Extratropical storm surge guidance...Na
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... .pzz825...inner waters from Point Arena to Pigeon Point... gale Wed night. .Pzz830...Inner waters from Pigeon Point to Point Piedras Blancas... gale Wed night. .Pzz835...Inner waters from Point Piedras Blancas to Santa Cruz Island, CA... gale today into Wed night. .Pzz840...Inner waters from Santa Cruz Island, CA to San Clemente Island, CA... gale today into Wed night.
.Forecaster kosier/Mills. Ocean prediction center.