Ribeira da Janela Surf Stats

The graph shows the combination of swells directed at Ribeira da Janela through a typical September, based on 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the optimum grid node based on what we know about Ribeira da Janela, and at Ribeira da Janela 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 were forecast only 5% of the time. Green and yellow represent increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In either 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 NNW, whereas the the prevailing wind blows from the NNE. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Ribeira da Janela and offshore. We combine these 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 surfable at Ribeira da Janela, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average September, swells large enough to cause good for surfing waves at Ribeira da Janela run for about 95% of the time.

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