marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 951 PM EDT Tue Jul 22 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
The IR Sat img show most of the conv ascctd with a fnrtl sysm ovr the srn wtrs with most of the ligtng confined to the wrn parts. The radar has strong tstms cells ovr the far srn wtrs. More widespread tstms cells are inland ovr the se states and are not slated to move into the fcst wtrs. At 23/00z a broad hgh pres contes as described below and a stnr frnt acrs the srn wtrs. The pres grdnt is quite slack and the Max obs winds are only 15 kt. The last ascat pass was at 1504z and had no winds above 15 kt. The seas are equally mediocore ranging btwn 2 and 4 ft and both nww3 multi grid and ecmwfwave hv very similar seas pattern and are very close to that of the obs. The glbl mdls hv initialized well and they agree on the few synop features in the short term. See no need to deviate from the previous fcst and so will keep the status quo. In the short term the frnt will drift N as a wrm frnt but will remain ovr the srn wtrs and will finally dsipt. The pres grdnt will remain slack ovr the entire area and so no winds wrngs N the fcst.
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Broad high pres over the region today will move se as cold front slowly appchs FM the NW. Models have had a good handle on the timnig of this front for a few days and agree no taking front off the coast N of Cape May arnd daybreak Thu. Expect current to change lttl. GFS/NAM/ECMWF/UKMET incrs SW winds to 20 to 25 kt Max ovr the Gulf of Maine Wed. By late Thu...front to extend FM S Nova Scotia SW to the VA CAPES...with lgt to mod SW winds ahd of the front. The GFS dvlps scndry wvs along the front then tracks them NE. This keep a SW gradient of 20 to 30 kt ahd of th frnot thru Fri. The ECMWF and UKMET support this but are not as agressive...esp with the last low Thu ngt/Fri. Will likely blend in the UKMET or ECMWF to smooth out these strngr ftrs. While the nthrn part of the front mvs off to the E...models agree on srn end dsipng nr httrs cnyn Fri ngt/Sat.
By sun...the GFS bcms an outlier ni bringing clds upr low acrs the grt lakes while the UKMET/ECMWF hold a wkr S/W WV fthr W and are more progressive ovr the ern Atlc. Prefer a UKMET/ECMWF fcst of dvlpng a weak sfc low ovt the mid Atlc rng by 12z sun...and taking this low ENE acrs the srn New England waters sun/sun ngt. The Gem lends some support to the GFS...but its 500 mb pttrn is more like the ECMWF/UKMET. Will follow a 70ecmwf/30ukmet blend and wl will fcst incrsng SW flow ovr thr srn and mid Atlc waters at this time...but limit winds to 25 kt due to model uncertainty.
.Seas...The 12z multigrid wavewatch iii initilized seas well... fwllng the 06z run which was about 1 ft too high. Fcst gdnc looks good and will be followed closely...except will transition over to the ECMWF wam over the weekend as the ECMWF winds field is preferred ovr the GFS winds.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster musonda/prosise. Ocean prediction center.