Porthjoke Surf Stats

This picture illustrates the variation of swells directed at Porthjoke through a typical September and is based upon 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the most applicable grid node based on what we know about Porthjoke. In the case of Porthjoke, the best grid node is 28 km away (17 miles). The rose diagram describes 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 were forecast only 12% of the time. Green and yellow show increasing swell sizes and largest 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 largest spokes, was W (which was the same as the most common wind direction). Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Porthjoke and out to sea. We group these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Porthjoke, you can view an alternative image 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 clean enough to surf waves at Porthjoke run for about 53% of the time.

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