marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 825 PM PDT sun Apr 20 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
The Sat img indct most of the conv clds assctd with a frntl bndry ovr the nrn wtrs. The radar show very isol tstms just ovr the N-ern portion of The Wash wtrs. At 21/0000z hgh pres 1025 mb along 130w just W of the srn wtrs has a ridge xtndg NE into the cntrl region with another ridge xtndg se passing just W of the srn wtrs. Low pres 998 mb about 360 nm NW of the region has a frnt strtchng se that continues se as a wrm frnt and SW as a cld frnt passing acrs the nrn wtrs and links up with a wrm frnt from low pres 1020 mb about 360 nm W of the cntrl region. Inland trof from low pres 1009 mb ovr AZ stretches NW along the CA coast. The pres grdnt is weak ovr most of the region xcpt the far nrn wtrs where the Max obs winds are 25 kt. The hghst seas are also confined to the nrn wtrs with 20 ft peaks ovr the NW parts. The last Jason pass at 2008z had 17 ft seas ovr the nrn wtrs. The nww3 multi grid WV mdl fits fairly well with the seas pattern xcept that it is underdone by up to 2 ft in some areas. Nww3 is also close to the ecmwfwave and has been quite consstnt with the fcst and so will stay with it for this update. The glb mdls have only a few synop features to agree on ovr the fcst wtrs and they have initilaized fairly well. In the short term the hgh pres will drift E as it dsipts while the low pres will zoom NE acrs the cntrl region as the cld frnt moves E acrs the nrn wtrs with its acctd low pres to the NW moving N then NW into the Gulf of AK. Another low pres will move from the NW twd the nrn wtrs. The pres grdnt will remain faily slack but as hgh pres builds from the W and the inland low pres trof deepens that will force isobars to pack up ovr the ern parts of the srn wtrs mid week. The energy curr in the Gulf of AK will be transfered se and that supports the deepening of the trof. All the mdls hv indctd enhanced winds ovr the ern parts of the srn wtrs. Both the ukmethr and ecmwfhr hv winds increasing to 30 kt while the GFS/CMC/NOGAPS and jma hv winds in the gale force range. So will reintroduce the gales ovr the srn wtrs in the xtndd prd.
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18z opc sfc analysis shows a dissipating warm front over the nrn pz5 waters W/a cold front entering the NW waters. A high pres ridge is present over the rest of the pz6 waters.
Through Wed night not many changes as the 12z guidance remains in decent agreement so favored 12z GFS through day 3. Cold front pushes through the pz5 waters tonight and nrn half of the pz6 waters Mon. A high pres ridge rebuilds over the nrn pz6 waters late Mon into Tue...while a weak low slides se across the pz5 waters Tue into Wed. Models begin to diverge a bit late Wed into thurs as the next low pres/frontal system approach the pz5 waters. While in general timing amongst the guidance is okay differences arise concerning the strength of the low...W/the 12z GFS/CMC suggesting gales in the nrn pz5 waters late Wed. W/this package decided to lean more towards a 12z GFS/ECMWF blend which still features the low but will keep winds below gale force Wed night in the nrn pz5 waters which is a change from the prior forecast. Beyond that the low moves N of the waters thurs while weakening and another frontal boundary approaches from the W Fri.
Over the pz6 waters decided to continue W/gales late Tue in the NE srn CA waters as the low pres trough strengthens along the coast but confdc is low to MDT at the moment.
.Seas...Favored 12z nww3 where 12z GFS winds were favored W/blend of 12z nww3/ECMWF wave model were a 12z GFS/ECMWF blend was used.
.Extratropical storm surge guidance...N/A.
.Warnings...Preliminary. Any changes will be coordinated through AWIPS 12 planet chat or by telephone:
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... .pzz840...inner waters from Santa Cruz Island, CA to San Clemente Island, CA... gale Tue. Gale possible Tue night.
.Forecaster musonda/Holley. Ocean prediction center.