marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 320 PM EDT Wed Jun 20 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Current conditions...the 12z NCEP surface analysis shows a stationary front bowing roughly E to W across the central nt2 waters into the Cape Henry region. Otherwise, the analysis indicates weak high pressure ridging over the offshore waters. Latest available ascat and ascat hi-res passes from a few hours ago indicates 5 to 15 kt winds across the offshore waters. Lightning density product data at 1840z shows a line of scattered showers and tstms along the cold front in the outer zones of the central nt2 waters.
Models/forecasts...the 12z medium range models are in good overall agreement across the offshore waters for tonight into sun. The 12z CMC is showing large timing differences for the Mon and Mon night timeframe, while the 12z UKMET is significantly faster than the other models with the cold front on Mon and Mon night, and the 12z ECMWF/GFS area showing the best agreement for late sun through Mon night. Will use the 12z ECMWF for the wind grids over the entire forecast period, since it is still showing very good run to run consistency and has good support from the latest wpc medium range forecaster guidance. With the except of the 12z CMC near the end of the forecast period, all of the models indicate that the winds will remain at below gale force through Mon night, so confidence is very good for no hazard grids during the forecast period. Am not planning to make any significant changes to the current model trend at this time.
Seas...the 12z emcwf wam and 12z wna wavewatch both initialized well over the coastal and offshore waters versus the latest buoy observations and altimeter data, with seas 5 ft or less over the offshore waters. The models are in good agreement through the forecast period, with only a few minor differences noted mainly during the Fri into Sat timeframe. Will go with a 2:1 blend of the 12z ECMWF wam/wna wavewatch to smooth out the model differences while maintaining consistency with the preferred 12z ECMWF wind grids.
Extratropical storm surge guidance...N/A.
.Nt1 New England waters... None.
.Nt2 mid-Atlantic waters... None.
.Forecaster Scovil. Ocean prediction center.