Furnas Surf Stats

The rose diagram illustrates the range of swells directed at Furnas over a normal December. It is based on 3200 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the optimum grid node based on what we know about Furnas, and at Furnas the best grid node is 12 km away (7 miles). The rose diagram illustrates the distribution of swell sizes and directions, 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 occurred only 7% of the time. Green and yellow represent increasing swell sizes and red represents the largest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the most common swell direction, shown by the longest spokes, was WNW, whereas the the most common 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 Furnas and out to sea. We combine these with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Furnas, 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 December, swells large enough to cause good for surfing waves at Furnas run for about 93% of the time.

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