Sandy Bay Surf Stats

The rose diagram illustrates the variation of swells directed at Sandy Bay through an average May, based on 3422 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the best grid node based on what we know about Sandy Bay. In this particular case the best grid node is 22 km away (14 miles). The rose diagram illustrates the distribution of swell sizes and directions, 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 happened only 52% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the dominant swell direction, shown by the longest spokes, was NW, whereas the the most common wind blows from the WSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Sandy Bay and out to sea. We combine these with the no surf category of the bar chart. To keep it simple we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Sandy Bay, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical May, swells large enough to cause surfable waves at Sandy Bay run for about 22% of the time.

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