Usami Surf Stats

The rose diagram describes the variation of swells directed at Usami over a normal October and is based upon 3471 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 optimum grid node based on what we know about Usami. In the case of Usami, the best grid node is 77 km away (48 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 represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These happened only 55% of the time. Green and yellow illustrate increasing swell sizes and red shows the highest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell was forecast. The diagram indicates that the prevailing swell direction, shown by the largest spokes, was E, whereas the the dominant wind blows from the NE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Usami 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 graph. Because wind determines whether or not waves are clean enough to surf at Usami, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical October, swells large enough to cause surfable waves at Usami run for about 7% of the time.

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