Kahana Bay Surf Stats

The figure illustrates the range of swells directed at Kahana Bay through an average April, based on 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the optimum grid node based on what we know about Kahana Bay. In the case of Kahana Bay, the best grid node is 39 km away (24 miles). The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks 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 only 49% of the time. Green and yellow show increasing swell sizes and red illustrates largest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell occurs. The diagram indicates that the dominant swell direction, shown by the biggest spokes, was NE, whereas the the most common wind blows from the E. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Kahana Bay and away from the coast. We group 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 clean enough to surf at Kahana Bay, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause surfable waves at Kahana Bay run for about 51% of the time.

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