marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 255 PM EDT Wed 23 Apr 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
1420z and 1520z hi res ascat-a and -b overpasses returned Max winds of 30 kt along a 39n71w to 35n75w line where Max SST gradient lies. NW winds should continue to increase this afternoon thru tngt. Have high level of confidence with previously forecast gales tda thru Thu ngt. There remains potential for winds to briefly reach storm force Thu evening over nern nt2 zones specifically anz905 and anz910 where SSTs are in 23 to 26 c range. 00z hi res ECMWF indicates 50 to 60 kt 925mb winds which could mix given low lvl lapse rates -12 to -14 here. With 12z GFS trending a bit stronger and past few runs of NAM indicating 50 kt at 975mb will go ahead and upgrade to marginal storm wrngs over above two zones late Thu into Thu ngt with about avg forecast confidence.
12z mdls are in good agreement that high pres ridge should exit the coast Thu ngt and Fri passing E of offshore waters by early Sat. Mdls diverge late Fri thru sun with next shrtwv approaching mid Atlc coast and then upper low thru Great Lakes and new engl Sat/sun. 12z GFS is a bit more progressive with cold front Fri ngt and Sat than 12z UKMET or 12z ECMWF. The latter mdls are more emphatic with dvlpg sfc low along front off mid Atlc coast Fri ngt and preferring ECMWF/UKMET which will increase winds to 25 or 30 kt over nrn mid Atlc zones Fri ngt into Sat ngt. Then as low deepens E of new engl/nrn mid Atlc waters plan to blend 12z GFS and 12z ECMWF close to 50/50 which will result in NW winds to 25 or 30 kt N of balt cnyn but mainly over outer offshore waters. Do not have sufficient confidence to add any NW gales at this time given mdl differences.
12z multigrid wavewatch iii continues about 2 to 3 ft too high with sig WV hgts off mid Atlc coast N of Hatteras this afternoon. As in previous forecast for later tda into Fri the slightly hier 00z ECMWF wave mdl is favored with NW gales. With preference for ECMWF over the weekend WV hgt grids will reflect 12z ECMWF wave except will tone down these sig WV hgts sun by a couple ft.
.Extratropical storm surge guidance...12z estofs indicating a negative surge more than double that of the 12z etss with values -1.5 to -2 ft from Delaware Bay to Long Island Sound Thu and Thu ngt. Whereas 12z etss is in 0 to -0.5 range. Based on previous cases the estofs is likely overdone with negative surge...with etss or at least a blend of the two seeming more reasonable.
.Nt1 New England waters... .anz800...Gulf of Maine... gale tonight into Thu. .Anz805...Georges Bank east of 68w... gale tonight into Thu night. .Anz900...Georges Bank west of 68w... gale tonight into Thu night. .Anz810...South of New England... gale tonight into Thu. .Anz815...South of Long Island... gale tonight into Thu.
.Nt2 mid Atlc waters... .anz820...Hudson Canyon to Baltimore Canyon... gale tonight. .Anz915...Hudson Canyon to the great South Channel... gale today into Thu night. .Anz920...Baltimore Canyon to the great South Channel... gale today into Thu night. .Anz905...The great South Channel to the Hague line... gale tonight. Storm Thu into Thu night. .Anz910...East of the great South Channel and south of 39n... gale tonight into Thu. Storm Thu night. .Anz825...Inner waters from Baltimore Canyon to Cape Charles Light... gale tonight. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale today into tonight.
.Forecaster Clark. Ocean prediction center.