Roca Alta Surf Stats

This picture shows the variation of swells directed at Roca Alta through a typical October and is based upon 3470 NWW3 model predictions since 2006 (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 Roca Alta, and at Roca Alta the best grid node is 6 km away (4 miles). The rose diagram illustrates 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 happened 25% of the time. Green and yellow show increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how commonly that size swell happens. The diagram implies that the prevailing swell direction, shown by the largest spokes, was NE, whereas the the prevailing wind blows from the NW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Roca Alta and away from the coast. We lump these in 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 Roca Alta, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average October, swells large enough to cause surfable waves at Roca Alta run for about 75% of the time.

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