Itaipu Surf Stats

The graph shows the variation of swells directed at Itaipu over a normal May. It is based on 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the optimum grid node based on what we know about Itaipu, and at Itaipu the best grid node is 39 km away (24 miles). The rose diagram illustrates the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 1.9% 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 frequently that size swell happens. The diagram suggests that the most common swell direction, shown by the longest spokes, was SSE, whereas the the prevailing wind blows from the ENE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Itaipu 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 Itaipu, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical May, swells large enough to cause surfable waves at Itaipu run for about 9% of the time.

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