marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 913 am EDT Fri Aug 1 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
GOES WV imgry indc an upr trof ovr the ern conus...and a rdg to the E of the ofshr wtrs. The IR/vis imgry shows ts Bertha S of the area and a wk frntl bndry acrs the ofshr wtrs...and lgtng data indc tstms ovr the nt2 wtrs alng the frnt. The prev fcst had mention of tstms...so wl keep in the update pkg.
The 06z GFS has not changed much FM the prev run...indcg the upr pttn wl not change significantly thrut the fcst pd. The biggest fcst prblm rmns the track of Bertha...and the last NHC advsry indc it wl pass just E of the srn nt2 wtrs. With all the mdls indcg the mid- lvl rdg ovr the ern conus...the steering shud take Bertha to the N and then NE by next week. The GFS is slgtly E of the ecwmf soln...and the bulk of the guid is a bit W of the GFS. The GFS h5 trof is not surprisingly just se of the rest of the guid...which would explain the GFS track. Also...most solns indc a wk shrwv wl mov ovr the nrn ofshr wtrs Tue into Wed...and sevl solns introduce a low at the sfc. The shrtwv also causes the steering to turn more N-S...which could bring Bertha closer to the ofshr wtrs. Otrw the ofshr wtrs wl rmn under the influence of the rdg to the E...and stay in SW flow for a majorty of the pd. For the update...wl be flwg NHC track for the fcst on Bertha...and wl stay near continuity for the rmndr of the fcst pd.
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Note: the offnt1 and offnt2 will be issued later than normal because the NHC ofcl fcst track of T.S. Bertha crosses the ofshr wtrs.
Summary...satpix and latest sfc analysis indicate a stnry fnt extndg NE to SW across the nt2 wtrs tonite...with lightning strike product showing a line of isold to sct showers/tstms just E of the fntl bndry...and also over the far srn nt2 zones. Latest ascat hi-res passes at 01z and 02z show only light winds over all of the ofshr zones...so the stnry fnt is considered to be a weak ftr.
The stnry fnt will drift W and NW as a weak warm front late today into Sat nite...as a hi pres rdg blds W toward the ofshr areas. The fnt shd become nrly stnry alg the coast sun nite...then dsipt Mon as rdg blds W over the ofshr waters Mon and Mon night. Tropical Storm Bertha is expctd to move N and approach the se nt2 wtrs Mon nite...then pass just se of the nt2 area Tue and Tue nite.
Models...the Med rng mdls are in gud overall agreemnt across the ofshr wtrs into Mon...but there are signif diffs over the Mon nite thru Tue nite timeframe concerning the track and timing of Bertha. The latest 00z NHC fcst track for Bertha matches up best with the old 12z UKMET and 00z Gem. The main problem is the 00z Med rng mdls do not show gud continuity with their prev run wrt to Bertha. Based on the 09z preat3...the NHC track fcst is going to closely follow the 00z GFS...so I will be favoring the 00z GFS for the wind grids thru the entire fcst prd.
.Seas...Will be using the wna version of the 00z multigrid ww3 for the sea ht grids thru the fcst prd...since am using the 00z GFS for the wind grids as noted above.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster Kells/Scovil. Ocean prediction center.