Statistiques de Surf de Barra do Sai

The figure shows the variation of swells directed at Barra do Sai over a normal August, based on 3574 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the optimum grid node based on what we know about Barra do Sai. In the case of Barra do Sai, the best grid node is 15 km away (9 miles). The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These were forecast 70% of the time. Green and yellow illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how often that size swell occurs. The diagram indicates that the most common swell direction, shown by the longest spokes, was SSE, whereas the the prevailing wind blows from the E. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Barra do Sai and offshore. We group 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 Barra do Sai, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical August, swells large enough to cause surfable waves at Barra do Sai run for about 30% of the time.

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