marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 840 PM EDT Sat may 26 2018
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Current conditions...the 18z NCEP surface analysis shows a cold front extending roughly E to W across the northern Gulf of Maine, with a low pressure trough approaching the mid Atlantic coast. Otherwise, the analysis shows a high pressure ridge over the offshore waters. Latest available ascat and ascat hi-res passes from this morning shows 15 to 20 kt wind in SW flow over the nt1 and northern nt2 waters, with 5 to 15 kt across the remaining offshore waters.
Models/forecast...the 12z medium range models are in good agreement across the offshore waters during the forecast period, except they are disagreeing somewhat regarding a low pressure system that is expected to track E across the central nt2 waters on Tue and Tue night. Will use the 12z GFS 10m solution for the wind grids for tonight into early Mon for consistency purposes, then go with the 12z ECMWF for later Mon through the rest of the forecast period, since it is a good median model solution for Tue and Tue night. Confidence in the forecast is slightly above average, due to the good model agreement for most of the forecast period. Am not planning to make any significant changes to the current forecast trend at this time.
Seas...the 12z wna wavewatch and 12z ECMWF wam both initialized well over the coastal and offshore waters versus the latest buoy observations and altimeter data. In order to be consistent with the preferred wind grids, the 12z wavewatch will be used for the sea height grids for tonight into early Mon, followed by the 12z wam for later Mon through the rest of the forecast period.
Extratropical storm surge guidance...N/A.
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Global models in good agreement through most of the forecast period, with only a few minor differences here and there. For the wind grids, will lean towards the 12z GFS through 12z Mon, then switch towards the 12z ECMWF thereafter.
Models in general good agreement with timing of cold front to move offshore across the northern waters tonight. Front then expected to stall right along the nt1/nt2 border sun. Models are in good agreement with an area of low pressure developing over the waters along the frontal boundary late sun, and moving east along the boundary Sun night into Mon. No significant changes in the latest guidance from previous run and was in line with current forecast trend. No major changes expected in the forecast with this system.
Models trying to come into some agreement on an area of low pressure developing and moving east across the central nt2 waters Tue into Tue night. GFS a bit faster with the track of this low than other guidance. Still prefer the ECMWF solution for this system as it continues to be a good compromise.
High pressure then expected to move southeast over the nt1 waters Wed and Wed night, and into the northern nt2 waters Thu and Thu night.
.Seas...Wave guidance within a foot or two of current observations. For the wave grids, will lean towards the 12z enp until 12z Mon, then switch towards the 12z ECMWF thereafter.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... None.
.Nt2 mid-Atlantic waters... None.
.Forecaster Scovil/achorn. Ocean prediction center.