marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 237 PM EST sun Nov 23 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Two main events for this forecast period. Fortunately...the models have come into better agreement through the forecast period. First event is srly gales dvlpng tonight in the almot 60 mb gradient dffrnc btwn strong wrn Atlc high and strng low mvng NE into the Great Lakes. GFS has been consistent on S to se winds incrsng to 30 to 35 kt early tngt S of balt cnyn...with gales spreading into the srn new engand waters by mrng. Both the UKMET and ECMWF 10m winds are quite smlr so cnfdnc is high. Under a 75 kt 925 mb ll jet...area of srly gales wl migrate into the nrn waters Mon. Wud not be srprsd to see some of the higher obsrvng platform to gust to 45 kt. May incrs the tstms tngt and Mon off the se coast as the sref is quite enthustc about cnvtvn here and ecwn has a grtr than 50 pct chc of svr tstms.
GFS/ECMWF/UKMET almost idntcl in timing of front pushng E over the waters Mon ngt and Tue...with gradu W to SW dmnshng winds. Models consistent in fcstg low to dvlp ovr the ern gf of mex and mov NE alng stnry front to just se of Cape Romain by 12z Wed. The new GFS is nearly idenical to its 00z run and agrees well with the ECMWF mean...and wpc man progs. The ECMWF and UKMET remain slgtly W of the GFS track. The new UKMET is about 6 hours faster. The NAM/Gem and parallel GFS remain E of the GFS and weaker. By 12z Thu...expect low to be nr the srn tip of Nova Scotia. Area of gales wl dvlp arnd the low early Wed then expand as low deepens and mvs NE.
Qstn rmns on strngth of the winds. The GFS dvlps storm frc winds ahd of assd front Wed ngt...these look ovrdn. Concerned about psbl storm frc winds on back side of low...as dpctd by the GFS 10m winds. The GFS and UKMET are the strngst...and the op GFS is in the middle of the ensmbl members. Given the event is almost 96 hrs aways and length of time of the strngst winds is short...wl limit winds to 47 kts...but otw blv this wl likle dvlp into a storm as the GFS tends to underplay these types of events...esp early in the season. Expect gales to quickly end by early Thu as los mvs off to the NE and front sweeps eastwrd.
Global models in general agrmnt on lrg high pres building ltr offshr later Thu thrugh Fri ngt. Qstn is strngth of the NW flow and pinning dwn the area of strngst winds...as the GFS hints at psbl NW gales early Fri. Wl blend in the UKMET and ECMWF gradients and cap winds at 30 kt.
.Seas...At 18z...obsrvd wave hgts are close to the 12z multigrid wavewatch iii gdnc. The ECMWF wam seas are generally 10 to 25 pct higher..esp in the srly flow and looks ovrdn. Wl use the ww gdnc but dcrs seas off the se coast early tngt as the GFS blvs winds are se to 40 kt off the SC coast now. Will trim back seas a ft or two in the srly flow...and incrs seas slgtly in the nrly flow. Worth noting...the wavewatch ensmbl has psbl Max seas of 35 ft nr 38n 60w late Wed.
.Extratropical storm surge guidance...The etss and estofs hv a neg surge of 1 to 2 ft off the mid Atlc and srn New England coast tngt...that lasts into Mon ngt. This is fllwd by a pos surge of 1 to 2 ft in nearly the same areas dvlpng Wed ngt.
.Nt1 New England waters... .anz800...Gulf of Maine... gale Mon into Mon night. Gale possible Wed night into Thu. .Anz805...Georges Bank west of 68w... gale Mon into Mon night. Gale possible Wed night. .Anz900...Georges Bank east of 68w... gale Mon into Mon night. Gale possible Wed night into Thu. .Anz810...South of New England... gale Mon. Gale possible Wed night. .Anz815...South of Long Island... gale Mon. Gale possible Wed into Wed night.
.Nt2 mid Atlc waters... .anz820...Hudson Canyon to Baltimore Canyon... gale tonight into Mon. Gale possible Wed into Wed night. .Anz915...Hudson Canyon to the great South Channel... gale Mon. Gale possible Wed into Wed night. .Anz920...Baltimore Canyon to the great South Channel... gale Mon. Gale possible Wed into Wed night. .Anz905...The great South Channel to the Hague line... gale Mon into Mon night. Gale possible Wed night into Thu. .Anz910...East of the great South Channel and south of 39n... gale possible Wed night into Thu. .Anz825...Inner waters from Baltimore Canyon to Cape Charles Light... gale tonight into Mon. Gale possible Wed into Wed night. .Anz828...Inner waters from Cape Charles Light to Currituck Beach Light... gale tonight. Gale possible Wed into Wed night. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale Mon. Gale possible Wed into Wed night. .Anz830...Inner waters from Currituck Beach Light to Cape Hatteras... gale tonight. Gale possible Wed into Wed night. .Anz833...Inner waters from Cape Hatteras to Cape Fear... gale tonight. Gale possible Wed. .Anz930...Outer waters from Hatteras Canyon to Cape Fear... gale Mon. Gale possible Wed into Wed night. .Anz835...Inner waters from Cape Fear to 31n... gale tonight. Gale possible Wed. .Anz935...Outer waters from Cape Fear to 31n... gale possible Wed.
.Forecaster prosise. Ocean prediction center.