Backdoors Surf Stats

The rose diagram illustrates the variation of swells directed at Backdoors through an average May and is based upon 3440 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 optimum grid node based on what we know about Backdoors, and at Backdoors the best grid node is 45 km away (28 miles). The rose diagram shows the distribution of swell directions and swell sizes, 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 occurred only 0.8% of the time. Green and yellow illustrate increasing swell sizes and red represents largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell was forecast. The diagram suggests that the most common swell direction, shown by the longest spokes, was SW (which was the same as the most common wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Backdoors and offshore. We combine these 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 surfable at Backdoors, 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 good for surfing waves at Backdoors run for about 99% of the time.

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