marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 345 am EDT Sat Oct 21 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Current conditions...the 00z NCEP surface analysis shows a cold front extending SW into the far NE part of the nt2 waters, with a weak low pres trough extending SW into the Gulf of Maine. Otherwise, the surface analysis shows a high pres ridge over the remaining nt2 waters. Latest available ascat hi-res and ascat passes from a few hours ago show 15 to 20 kt winds over the Georges Bank and NE nt2 waters, and 10 to 15 kt winds elsewhere in the offshore waters.
Models/forecast...the 00z medium range models are in good agreement across the offshore waters for today through Mon night, so the representative 00z GFS 10m/30m solution with the stability smart tool will be used for the wind grids during this timeframe. A strong cold front is expected to approach the East Coast late Tue, then move E across the offshore waters Tue night through Wed night. The 00z GFS is faster than the other models with the cold front, and thus is not a preferred model solution for Tue through Wed night. All of the 00z medium range models now indicate gales in the S flow ahead of the cold front for Wed and Wed night, even though the GFS has stronger gales while the ECMWF/Gem/UKMET have marginal gales, so confidence is now high enough for gales to be introduced for Wed and Wed night. Since the 00z ECMWF has good support from the 00z Gem/UKMET, it will be used for Tue through the rest of the forecast period.
Seas...the 00z wna wavewatch and 00z ECMWF wam both initialized within a foot or two of the observations in the offshore waters. Both of the models are in very good agreement over the offshore waters for today through Mon, with a few minor differences developing on Mon night in the nt2 waters. A 50/50 blend of the 00z wavewatch/ECMWF wam will be used for the wave height grids through Mon night. Then will be using the 00z ECMWF wam exclusively for Tue through the rest of the forecast period, in order to be consistent with the preferred 00z ECMWF wind grids.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... .anz805...Georges Bank west of 68w... gale possible Wednesday night. .Anz900...Georges Bank east of 68w... gale possible Wednesday night.
.Nt2 mid-Atlantic waters... .anz920...Baltimore Canyon to the great South Channel... gale possible Wednesday into Wednesday night. .Anz905...The great South Channel to the Hague line... gale possible Wednesday night. .Anz910...East of the great South Channel and south of 39n... gale possible Wednesday into Wednesday night. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale possible Wednesday into Wednesday night.
.Forecaster Scovil/Scovil. Ocean prediction center.