marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 248 PM EDT Thu may 25 2017
.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 models have converged towards very similar forecast tracks for the surface low now approaching the nrn mid Atlantic coast to track NE across the srn New England coast tonight, pass E across the Gulf of Maine Fri, then pass E of the nt1 waters Fri night into Sat. The models also share similar timing for an associated warm front to lift N into the nt1 waters tonight/early Fri, while at the same time the low pulls a cold front E across the waters tonight into late Fri. In regards to the forecast gradients associated with these fronts, N of the warm front per the now slightly weaker 12z GFS it looks more marginal if the previously forecasted Ely gales will develop in nt1 zone anz800 early tonight. But for now with the 12z NAM/Gem forecasting slightly stronger Ely gradients and the usually conservative 12z UKMET/ECMWF forecasting solid 25-30 kt boundary layer (bl) winds, will go ahead and continue with this Gale Warning. Further S in association with the cold front, with all of the models forecasting gale force associated bl winds (which were confirmed by an earlier 1528z high resolution ascat-a scatterometer pass), forecast confidence is significantly higher that gales will continue across the central nt2 waters, primarily in the vicinity of the Gulf Stream. Therefore, similar to the previous offshore forecast package for tonight through Sat, plan on populating our forecast wind grids with our smart tool that will place stronger 12z GFS first sigma level winds in unstable areas and weaker 12z GFS 10m winds in stable areas (which will be primarily from the Gulf Stream northward). So per these winds, do not anticipate making any major timing and/or areal coverage changes to the previously forecasted gale warnings.
In the long range, the 12z models continue to forecast an ill defined pattern with weak associated features (with sub gale force winds). Versus its previous respective runs, the 12z GFS is now more progressive in forecasting a weak surface low to track E along a stationary front across the central nt2 waters Sat night into Sun night. The 12z Gem supports this solution, but the 12z gefs mean indicates that the 12z GFS is likely too fast with this low, which is also evidenced by the less progressive 12z UKMET/ECMWF solutions. The 12z GFS/Gem are then similar in forecasting the front to lift slowly nwd Mon/Mon night with several weak lows tracking E along the front, while the 12z UKMET forecasts a more progressive warm fropa with a stronger associated frontal wave. Since its less progressive than the 12z UKMET and not quite as slow as the 12z GFS/Gem, the 12z ECMWF looks like perhaps a reasonable compromise for this warm fropa. Then the 12z global models come into somewhat better agreement that a weak cold front will approach from the NW Tue, then push offshore into the nrn waters Tue night. So since its been somewhat more consistent, plan on favoring the 12z ECMWF solution for this long range pattern and as a result will populate with its bl winds on Sat night through Tue night.
.Seas...The slightly higher 12z wavewatch iii has intitialized the current seas better than the 12z ECMWF wam. With this in mind and since the 12z GFS solution will be favored, will populate our forecast wave grids with 12z wavewatch iii seas for tonight through Sat. Then since the 12z ECMWF solution will become favored, will transition to populating with 12z ECMWF wam seas on Sat night through Tue night.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... .anz800...Gulf of Maine... gale tonight.
.Nt2 mid-Atlantic waters... .anz920...Baltimore Canyon to the great South Channel... gale tonight into Friday. .Anz910...East of the great South Channel and south of 39n... gale tonight into Friday. .Anz828...Inner waters from Cape Charles Light to Currituck Beach Light... gale tonight. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale tonight into Friday. .Anz830...Inner waters from Currituck Beach Light to Cape Hatteras... gale tonight. .Anz833...Inner waters from Cape Hatteras to Cape Fear... gale today. .Anz930...Outer waters from Hatteras Canyon to Cape Fear... gale tonight.
.Forecaster vukits. Ocean prediction center.