Statistiques de Surf de Llanddwyn Island

This image describes the variation of swells directed at Llanddwyn Island through an average August. It is based on 3581 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the best grid node based on what we know about Llanddwyn Island. In this particular case the best grid node is 16 km away (10 miles). The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast 49% of the time. Green and yellow illustrate increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell happens. The diagram implies that the most common swell direction, shown by the largest spokes, was SW, whereas the the dominant wind blows from the WSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Llanddwyn Island and offshore. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Llanddwyn Island, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical August, swells large enough to cause clean enough to surf waves at Llanddwyn Island run for about 51% of the time.

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