Porthjoke Surf Stats

The figure shows the range of swells directed at Porthjoke through an average October, based on 3471 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the most applicable grid node based on what we know about Porthjoke, and at Porthjoke the best grid node is 28 km away (17 miles). The rose diagram describes the distribution of swell sizes and swell direction, 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 10% of the time. Green and yellow show increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In both graphs, 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 largest spokes, was W, whereas the the prevailing wind blows from the SW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Porthjoke and away from the coast. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Porthjoke, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical October, swells large enough to cause surfable waves at Porthjoke run for about 66% of the time.

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