The legacy OPC website URL https://www.opc.ncep.noaa.gov permanently redirects to https://ocean.weather.gov. On or after July 9, 2019 the old URL will not work. Users must use https://ocean.weather.gov to access the OPC website. More information is available at https://www.weather.gov/media/notification/scn19-10opc_terminate.pdf.
 
PLEASE NOTE: This .shtml webpage is going to be converted to .php format on June 4, 2019. On that date you will need to replace ".shtml" with ".php" in the URL address bar. The actual page content will remain the same. More information is available at https://www.weather.gov/media/notification/scn19-11opc_shtml.pdf.

About Marine Weather Discussion (MWD)

This product describes expected warnings over areas in the offshore waters of both the Atlantic and Pacific Oceans and is used for coordination with National Weather Service Forecast Offices. The narrative may highlight wind speeds and wave heights in relation to current forecasts and computer model guidance.  This product is produced four times daily.

Description of synoptic and mesoscale features expected to affect areas in and adjacent to offshore waters in both the Atlantic and Pacific Oceans. The narrative describes weather, wind speeds, and seas focusing mainly on conditions through the next 48 hours. It emphasizes timing and issuance of warnings. 

The MWD includes future trends of wind and sea conditions, effects of currents such as the Gulf Stream in the Atlantic Ocean, and how the latest  computer model guidance is handling features of significance to the mariner.

The product includes confidence levels for warning criteria for extratropical storms and related weather features that can produce such conditions. Confidence is based on the level of model agreement, and may take into account known model biases that affect would likely affect the forecast.

The area described in the MWD covers the offshore and adjacent waters of the Western North Atlantic Ocean and the Eastern North Pacific Ocean.