Statistiques de Surf de Mana Island

The figure describes the combination of swells directed at Mana Island through a typical November, based on 3347 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the most applicable grid node based on what we know about Mana Island. In this particular case the best grid node is 25 km away (16 miles). The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These were forecast only 49% of the time. Green and yellow show increasing swell sizes and red shows highest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell occurs. The diagram suggests that the dominant swell direction, shown by the biggest spokes, was NW (which was the same as the dominant wind direction). Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Mana Island and out to sea. 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 clean enough to surf at Mana Island, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average November, swells large enough to cause surfable waves at Mana Island run for about 51% of the time.

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