Mana Island Surf Stats

The graph describes the variation of swells directed at Mana Island through an average June, based on 3266 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the most applicable grid node based on what we know about Mana Island, and at Mana Island the best grid node is 25 km away (16 miles). The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 63% of the time. Green and yellow illustrate increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how commonly that size swell happens. The diagram implies that the prevailing swell direction, shown by the biggest spokes, was NW, whereas the the dominant wind blows from the W. 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 lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose diagram. 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 expected to coincide with glassy or offshore wind conditions. In a typical June, swells large enough to cause surfable waves at Mana Island run for about 37% of the time.

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