marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 200 PM EST Tue Nov 25 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Over the short term...the new 12z mdls overall remain in good agrmt that the most sig wx feature over the next svrl days wl be a sfc low dvlpg on a front and movg NE to off the se coast tonite...intensfyg and tracking NNE off the mid Atlc coast to nr the 40n70w benchmark by early Wed evening (27/00z)...then contg NE acrs the nt1 wtrs Wed nite. In regards to the fcst track of this dvlpg low...other than the 12z global Gem contg to look lk a too far E (and also too weak) outlier...the other 12z mdls now fcst nrly indentical tracks with just minor timing differences. The 12z gefs mean indicates that the 12z GFS track is slightly too fast (by abt 3 hrs). Therefore a non-Gem 12z mdl consensus looks fine for a now high confidence fcst track. In rgrds to the fcst gradients ascd with this low...the 12z GFS/gfsp/UKMET/ECMWF all fcst very smlr timing and areal coverage for their gale force ascd bl winds. The biggest fcst challenge is whether this system wl attain storm force winds as prevly fcstd Wed nite as it passes just se of cp cod. Tho smlr to their prev 06z runs...the 12z GFS/gfsp fcst only solid 35-45 kt 30m bl and the usually conservative 12z UKMET fcstg 35-40 kt bl winds...am tempted to drop the storm wrngs. But with this low fcst to track invof the W wall of the Gulf Stream as it passes NNE acrs the nt2 wtrs...and the fact that the 12z gefs mean indicates that the 12z GFS may not be fcstg its low to intensify fast enuf (also noting the mr rapid 12z UKMET/ECMWF intensification)...believe the 12z GFS ascd bl winds may be too low. Therefore wl keep the prevly fcstd wrngs in place with this low. Then in the wake of this system the 12z GFS/gfsp/UKMET/ECMWF remain consistent vs their prev respective runs in fcstg a scndry cold front and/or sfc trof to mov ofshr acrs the nt2 wtrs Thu/Thu nite which wl cause the wnwly gradient to restrengthen. A consensus of these mdls looks rsnbl for the fcst strength of this gradient for now (gnrly up to 25 or 30 kt)...but wl hv to keep an eye out for potential gales dvlpg in the vcnty of the Gulf Stream. So with the 12z mdls rmng consistent...for the short term plan on contg to use the prevly populated slightly stronger 00z GFS 30m bl winds with just sm minor additional edits per the 12z mdls which wl result in no sig timing and/or areal coverage chngs to the prevly fcstd short term wrngs.
In the long range...the 12z global mdls gnrly agree that high pres wl bld twds the mid Atlc coast Fri...mov ofshr Fri nite/Sat...then maintain a ridge acrs the srn nt2 wtrs Sat nite into sun nite with strengthening sswly return flow dvlpg acrs the nrn wtrs. In comparison to the other 12z global mdls it looks lk the 12z GFS is fcstg this return flow to strengthen too quickly. Then on sun/sun nite...to be mr in line with the latest wpc medium range guidance...wl favor the slower 12z gfsp/UKMET/ECMWF solution for a cold front aprchg FM the NW and movg ofshr into the nrn wtrs late sun nite. Therefore in the long range wl go with a blend the current 00z GFS 30m bl winds and 12z ECMWF bk winds for Fri/Fri nite...then wl transition to all 12z ECMWF bl winds for Sat thru sun nite. So as a result no major long range chngs are anticipated for the next ofshr fcst package.
Seas...with the 12z wavewatch iii and 12z ECMWF wam rmng consistent thru the short term wl not repopulate the prevly used fcst wave grids thru Thu nite. Then wl blend the current grids with 50 percent of the 12z ECMWF wam for Fri/Fri nite...and then wl transition to all 12z ECMWF wam for Sat thru sun nite.
.Extratropical storm surge guidance...As the dvlpg low tracks NE up the coast the 12z etss and 12z estofs remain within .5 ft of each other in fcstg a Max surge gnrly in the 1.0 to 1.5 ft range to dvlp from Delmarva to cp cod Bay Wed into Wed night which overall looks reasonable.
.Nt1 New England waters... .anz800...Gulf of Maine... storm Wed night. .Anz805...Georges Bank west of 68w... gale Wed. Storm Wed night. .Anz900...Georges Bank east of 68w... gale Wed night. .Anz810...South of New England... gale Wed. Storm Wed night. .Anz815...South of Long Island... gale Wed into Wed night.
.Nt2 mid Atlc waters... .anz820...Hudson Canyon to Baltimore Canyon... gale Wed into Wed night. .Anz915...Hudson Canyon to the great South Channel... gale Wed into Wed night. .Anz920...Baltimore Canyon to the great South Channel... gale Wed into Wed night. .Anz905...The great South Channel to the Hague line... gale Wed into Wed night. .Anz910...East of the great South Channel and south of 39n... gale Wed into Wed night. .Anz825...Inner waters from Baltimore Canyon to Cape Charles Light... gale Wed into Wed night. .Anz828...Inner waters from Cape Charles Light to Currituck Beach Light... gale Wed. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale Wed into Wed night. .Anz830...Inner waters from Currituck Beach Light to Cape Hatteras... gale Wed. .Anz833...Inner waters from Cape Hatteras to Cape Fear... gale Wed. .Anz930...Outer waters from Hatteras Canyon to Cape Fear... gale Wed. .Anz835...Inner waters from Cape Fear to 31n... gale tonight into Wed. .Anz935...Outer waters from Cape Fear to 31n... gale Wed.
.Forecaster vukits. Ocean prediction center.