Zanzibar Surf Stats

The graph illustrates the variation of swells directed at Zanzibar over a normal 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 coastline so we have chosen the most applicable grid node based on what we know about Zanzibar, and at Zanzibar the best grid node is 35 km away (22 miles). The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without 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 92% of the time. Green and yellow illustrate increasing swell sizes and red represents largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the most common swell direction, shown by the largest spokes, was NNW, whereas the the most common wind blows from the E. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Zanzibar and out to sea. We group 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 Zanzibar, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical September, swells large enough to cause good for surfing waves at Zanzibar run for about 0% of the time.

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