marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 910 am EST Sat Dec 20 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Weak 1018 mb low pres is located off the NE coast of fla per the 12z prelim NCEP sfc analysis. A trof extends NE from the low to a psn off the Carolina coast. High pres extends from VA N into se Canada. The low will drift NE ovr the next day or two as the high also drifts NE. For the am update we will tweak the prev fcst slightly to fit a bit better with nearby cwf and TAFB fcsts... and the latest obs...ascat...and rapid-scat data. Otw...we will wait for a full set of 12z mdl guid before making any sig changes...if needed...to the ongoing opc fcst. Gales still appear lkly by the middle of next wk as an upr lvl trof slides NE from the central U.S. And assoc deepening sfc low pres tracks thru the OH valley into the grt lks.
Seas...sea hts range from nr 1 ft just off Long Island to 4 to 5 ovr wtrs well off the srn New England coast...to around 4 ft off the S Carolina coast. The obs off the Carolina coast are running about 2 ft abv the latest WV watch iii mdl guid. Again for the am update we will tweak the prev fcst to fit with the latest obs and nearby cwfs and TAFB fcsts...but otw...make no major changes to the prev opc fcst for the am update.
----------------------------------------------------------------- Previous discussion...
Summary...a high pres ridge will build ofshr today into sun...then shift NE across the nrn nt2 and nt1 wtrs sun nite thru Tue. Dvlpg low pres will form off the South Carolina coast sun nite...drift N over the mid Atlc waters near the coast Mon into Tue...then weaken as it aprchs the New Jersey coast later Tue and Tue nite. The low will pull a warm front N across the nt2 wtrs sun nite thru Tue. The warm fnt will lift N over the nt1 wtrs Tue nite thru Wed nite. A stg cold front will move E off the se coast Wed aftn...sweep ofshr of the mid Atlc coast late Wed...then move E over all of the ofshr areas Wed nite.
Models...the 00z Med rng mdls are in gud overall agreemnt across the ofshr wtrs thru the fcst prd...except they differ with the timing of the stg cold fnt during the Tue nite thru Wed nite prd. 00z Gem/NOGAPS are fastest with the cold fnt...while 00z UKMET is slowest...and 00z ecwmf/GFS are median solns wrt timing of this ftr. 00z ECMWF looks somewhat underdone with the S to se flow ahead of the fronts Tue nite thru Wed nite compared to the other mdls...so will use the 00z GFS 30m to populate the wind grids thru the entire fcst prd because the ECMWF/GFS are in excellent agreemnt wrt timing.
.Seas...The wna version of 00z multigrid ww3 mdl initialized within a ft or two of buoy obs over the ofshr wtrs. The 00z mww3 and 00z ECMWF wam are in close agreemnt into early Mon...so will populate the sea ht grids with the 00z mww3 for today into early Mon. The 00z mww3 and 00z ECMWF wam diverge somewhat during the later Mon thru Wed nite prd...so will be using a 50/50 blend of these mdls for this timeframe to smooth out the diffs.
.Extratropical storm surge guidance...Estofs is indicating a pos surge in the 1.0 to 1.5 ft rng alg the mid Atlc and new eng coasts for late Wed thru into early Thu...assocd with stg S to se flow ahead of a warm fnt and a cold fnt.
.Nt1 New England waters... .anz800...Gulf of Maine... gale possible Wed into Wed night. .Anz805...Georges Bank west of 68w... gale possible Wed into Wed night. .Anz900...Georges Bank east of 68w... gale possible Wed night. .Anz810...South of New England... gale possible Wed into Wed night. .Anz815...South of Long Island... gale possible Wed into Wed night.
.Nt2 mid Atlc waters... .anz820...Hudson Canyon to Baltimore Canyon... gale possible Wed into Wed night. .Anz915...Hudson Canyon to the great South Channel... gale possible Wed into Wed night. .Anz920...Baltimore Canyon to the great South Channel... gale possible Wed into Wed night. .Anz905...The great South Channel to the Hague line... gale possible Wed into Wed night. .Anz910...East of the great South Channel and south of 39n... gale possible Wed night. .Anz825...Inner waters from Baltimore Canyon to Cape Charles Light... gale possible Wed into Wed night. .Anz828...Inner waters from Cape Charles Light to Currituck Beach Light... gale possible Wed into Wed night. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale possible Wed into Wed night. .Anz830...Inner waters from Currituck Beach Light to Cape Hatteras... gale possible Wed into Wed night. .Anz833...Inner waters from Cape Hatteras to Cape Fear... gale possible Wed into Wed night. .Anz930...Outer waters from Hatteras Canyon to Cape Fear... gale possible Wed into Wed night. .Anz835...Inner waters from Cape Fear to 31n... gale possible Tue night into Wed night. .Anz935...Outer waters from Cape Fear to 31n... gale possible Wed into Wed night.
.Forecaster Mills/Scovil. Ocean prediction center.