marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 231 am EST Sat Nov 28 2015
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Cold front on the doorstep of the nt1 waters and the Gulf of Maine. Pre-front SW-ly flow has subsided slightly over the past few hours...and what was once 20-30 kt winds is now closer to 10-20 kt with an occasional ship ob to 25. Within just the next couple of hours winds shud shift as the front moves through.
Tda into late Mon the 00z cycle of model solns rmn in pretty good agreement. See no problems using the 00z GFS output thrut this time frame as the above mentioned cold front moves gradually S across the nrn portions this weekend bfr finally stalling nr latitude 36n by Mon morning. As the actual high center pushes farther se sun into Mon...stronger NE winds are xpctd to develop just after fropa. Per usual the 10m bl winds appear slightly lower than what we normally see in these scenarios...especially invof the Gulf Stream...and to account for the expected slightly hier winds will use a 75/25 blend with the 30m winds into about 00z Tue.
Tue and beyond the forecast becomes quite problematic as a lopres develops along the stnry front near the Outer Banks...then accelerates NE-Ward while intensifying ahead or along an aprchg cold front. Worth noting for the 3rd consecutive run the GFS has trended stronger and slightly faster with this initial developing low. 00z non-NCEP solns are split into two camps as the Gem/UKMET are faster/weaker...while the ECMWF develops a second stronger low along the cdfnt late Wed across the NW waters near the Gulf of Maine. The newest ECMWF cycle is appreciably stronger and slightly faster with this second low.
With such varying model solns and the fact that this is late d4 and beyond...for sake of forecast consistency will opt to leave the extended portions of the grids unchanged. Beginning 00z Tue will trend the official fcst towards the prev grids...which were based on the 27/12z ECMWF.
Seas...in similar fashion will use 00z ww3 wna thru late Mon...then transition the fcst twd prev grids based on the 27/12z ECMWF wam.
Extratropical storm surge guidance...00z etss guidance suggest pos surge values aprcgh a ft beginning Mon aftn into Tue from the VA CAPES N to abt Sandy Hook. These values certainly seem reasonably with all guidance suggesting a strong onshore flow during this time.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster Collins. Ocean prediction center.