Kohala Lighthouse Surf Stats

This image describes the combination of swells directed at Kohala Lighthouse over a normal May. It is based on 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the optimum grid node based on what we know about Kohala Lighthouse. In the case of Kohala Lighthouse, the best grid node is 30 km away (19 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing 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 85% of the time. Green and yellow illustrate increasing swell sizes and red shows highest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell was forecast. The diagram implies that the prevailing swell direction, shown by the longest spokes, was N, whereas the the dominant wind blows from the ENE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Kohala Lighthouse and away from the coast. We combine 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 surfable at Kohala Lighthouse, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical May, swells large enough to cause good for surfing waves at Kohala Lighthouse run for about 15% of the time.

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