marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 1017 am EDT sun Oct 21 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Current satellite pictures indicate a lot of cold air cumulus across the offsore waters behind an exiting frontal boundary. Many of the wave height observations at 12z are running abouve the guidance, although the wam is slightly better than wna eary in the forecast period. Since ascat passes are not likely across the offshore waters by the time I issue the forcast I likely will only make minor adjustments to the grids,
----------------------------------------------------------------- previous discussion...
Storm force winds still ahead of a cold front and now east of the forecast waters will keep moving east away from the forecast waters in the short term. GOES 16 rgb geocolor satellite images still show cold clouds with a band of lightning strikes within the vicinity of the cold front. The latest NCEP weather map has to the west a ridge that extends from high pressure to the northeast of the waters. A strong cold front stretches from Georges Bank across the region to the southwestern waters. Pressure gradient is fairly tight over the waters and maximum winds are in the storm force threshold with gale force winds over the northeastern waters. Stability index map show instability to continue over the region and that will spread gale force winds to central waters in the short term.
At 500 mb, upper level ridge is now east of the region and significant energy embedded in an upper level trough now over the mid west states will shift into the waters. The models agree well in the short term on pushing the energy swiftly across the region. Models still differ slightly on the timing of the energy as it moves east over the forecast waters.
The latest model run for GFS/ukmethr/ecmwfhr/CMC have initialized fairly well the synoptic surface observations though there are just minor differences on the actual position of the front over the waters. Models have continued to show enhanced winds near the Gulf Stream. For consistency, will retain most of the official forecast winds and will stay with GFS at first then switch to ECMWF in the extended period.
.Seas...They are initially relatively large over the eastern waters with a peak at 20 ft but can be higher in storm force winds. Nww3 and ecmwfwave have initialized well the observed seas. Both wave models still agree well in the short term on keeping larger seas to the east of the waters but will subside as the front passes over the waters. Seas will then build again over the central waters as gale force winds spread into the central waters. Will use nww3 for the seas grids.
.Extratropical storm surge guidance...There will be no significant positive surge events over the region for the next few days.
.Nt1 New England waters... .anz800...Gulf of Maine... gale today into tonight. .Anz805...Georges Bank west of 68w... gale today into tonight. Gale possible Thursday night. .Anz900...Georges Bank east of 68w... gale today into tonight. .Anz810...South of New England... gale today. .Anz815...South of Long Island... gale today.
.Nt2 mid-Atlantic waters... .anz820...Hudson Canyon to Baltimore Canyon... gale today. Gale possible Thursday. .Anz915...Hudson Canyon to the great South Channel... gale today. Gale possible Thursday into Thursday night. .Anz920...Baltimore Canyon to the great South Channel... gale today. Gale possible Thursday into Thursday night. .Anz905...The great South Channel to the Hague line... gale today into tonight. Gale possible Tuesday night. Gale possible Thursday night. .Anz910...East of the great South Channel and south of 39n... gale today into tonight. Gale possible Tuesday night. Gale possible Thursday night. .Anz825...Inner waters from Baltimore Canyon to Cape Charles Light... gale today. .Anz828...Inner waters from Cape Charles Light to Currituck Beach Light... gale today. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale today. Gale possible Thursday. .Anz830...Inner waters from Currituck Beach Light to Cape Hatteras... gale today. .Anz833...Inner waters from Cape Hatteras to Cape Fear... gale today. .Anz930...Outer waters from Hatteras Canyon to Cape Fear... gale today.
.Forecaster Shaw/musonda. Ocean prediction center.