Storm Atiyah, which affected Ireland on Sunday 8th December, created some mountainous seas off Ireland’s coast recorded by The Irish Weather Buoy Network. The M6 buoy, which is located approximately 200 miles off the west coast, measured an individual wave height of 19.5m (64ft) during the height of the storm.
An explanation of the Sea State Description, as used for Sea Area Forecast sea crossings, can be found here
Marine Weather Services Sea Area Map