.Marine weather discussion for N Atlantic Ocean .NWS ocean prediction center Washington DC 930 am EDT Fri 23 Jun 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
The latest models are consistent that the south to southwest winds across the offshore waters will gradually increase tonight through Saturday evening. There is some potential for winds to reach marginal gales across the northern outer nt2 waters over the Gulf Stream Saturday afternoon and evening. With this mornings forecast updates will continue to limit the winds to 30 kt, but will watch the trend in today's 12z guidance. At the moment we do not have sufficient forecast confidence to upgrade these outer zones to gales. The strength of the winds at the surface will largely depend on how stable the lower levels remain over the Gulf Stream. The 4km NAM which usually handles this better than the GFS, is obly showing marginally unstable low level lapse rates. The 00z/06z wavewatch iii and 00z ECMWF wam are both well initialized with the west Atlantic wave heights this morning. We will not be making any significant adjustments to the previous opc forecast grids.
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Summary...the 00z NCEP surface analysis shows a warm front extending roughly se to NW across the nrn nt2 and srn nt1 waters, with high pres ridges over most of the nt1 waters and across the srn and central nt2 waters. Latest available ascat hi-res and ascat passes from a few hours ago indicate 5 to 15 kt winds over the offshore waters.
Models...00z medium range models are in good overall agreement across the offshore waters through the forecast period, although there are some minor timing differences evident for Tue and Tue night. However, the 00z GFS 10m solution has good support from the latest wpc medium range forecaster guidance and appears to be representative enough to be used for the wind grids over the entire forecast period.
Seas...the 00z wna wavewatch and 00z ECMWF wam both initialized reasonably well over the coastal/offshore waters. The models are in good overall agreement across the offshore waters over the entire forecast period, with only minor differences noted. A representative 50/50 blend of the 00z wna wavewatch/ECMWF wam will be used for the sea height grids for the entire forecast period, in order to smooth out the model differences.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... None.
.Nt2 mid-Atlantic waters... None.
.Forecaster Clark/Scovil. Ocean prediction center.