marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 1021 PM EDT Tue Sep 2 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Hgh pres E of the region still xtnds a ridge into the srn wtrs and the glbl mdls fit well with the obs synop pattern. A cld frnt acrs the mid Atlc states is steadly approaching the nrn wtrs while a trof continues into the se states and the glbl mdls hv initialized well with these features. Weak ridging ovr the srn wtrs has maintained mostly SW winds acrs the region with hgr winds to 20 kt ovr the cntrl region which is inline with the last ascat at 1536z.
The glb mdls are in agrmnt ovr the short term but they differ slightly in the xtndd prd mainly because the syms are very weak and so mdls have problems in the depiction of cnters. Otherwise all the glbl mdls exhibit similar squence and path of the sysms acrs the fcst wtrs. The glbl mdls concensus on winds is mainly light winds from the wrn sectr. There are no mjr discrpncs and so will continue with GFS just like the previous forecast with no wrngs.
Most of the enrgy will keep passing N of the region with just sporadic small pockets of energy from the S reaching only the far srn wtrs. Synop features aloft suggest mostly zonal flow in the short term then a trof dips slightly S twd the end of the xtndd prd.
In the short term the hgh pres to the E of the srn wtrs will remain nrly stnry as it maintains a ridge acrs the srn wtrs. The cld frnt will mv E ovr the nrn wtrs then stall acrs the cntrl wtrs. In the xtndd prd the hgh pres will weaken and allow another cld frnt to approach the region wtrs.
----------------------------------------------------------------- Previous discussion...
Summary...a hi pres rdg will persist over the cntrl and srn nt2 wtrs thru the fcst prd. A weak cold fnt will move se over the nt1 and nrn nt2 wtrs tonite into Wed...cont se into the cntrl nt2 wtrs late Wed into Thu...then stall and dsipt over the srn nt2 wtrs late Thu into Fri. Another rdg will bld over the ofshr wtrs N of the fnt Thu...then shift se across the ofshr areas Thu nite thru Sat. Another cold fnt will move slowly se and aprch the new eng and New Jersey csts Fri nite into Sat...then move se over the nt1 and nrn nt2 wtrs later Sat thru sun nite.
Models...the 12z Med rng mdls are in vry gud overall agreemnt thru the fcst prd...except the Gem/UKMET are a ltl faster with the cold fnt over the Fri thru Sat nite timeframe. GFS 10m has stg support from the 12z ECMWF and latest wpc Med rng fcstr guidance...so it will be used for the wind grids over the fcst prd. Am not planning to make any signif changes to the current fcst trend.
.Seas...The 12z multigrid ww3 mdl initialized within about a foot of the obsrvd sea hts. The 12z mww3 and ECMWF wam are within a foot or two of each other thru the fcst prd...so will use the wna version of the 12z mww3 mdl for the wave ht grids.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster musonda/Scovil. Ocean prediction center.