Llanddwyn Island Surf Stats

The figure describes the range of swells directed at Llanddwyn Island through a typical November and is based upon 3346 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the optimum grid node based on what we know about Llanddwyn Island, and at Llanddwyn Island the best grid node is 16 km away (10 miles). The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast 50% of the time. Green and yellow illustrate increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how frequently that size swell was forecast. The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was SW, whereas the the dominant wind blows from the WSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Llanddwyn Island and out to sea. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Llanddwyn Island, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average November, swells large enough to cause clean enough to surf waves at Llanddwyn Island run for about 50% of the time.

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