Pontllyfni Surf Stats

The rose diagram describes the combination of swells directed at Pontllyfni over a normal May. It is based on 3438 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the optimum grid node based on what we know about Pontllyfni. In this particular case the best grid node is 11 km away (7 miles). The rose diagram illustrates the distribution of swell directions and swell sizes, 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 65% of the time. Green and yellow show increasing swell sizes and red shows highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell was forecast. The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was SW (which was the same as the dominant wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Pontllyfni and offshore. We combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are surfable at Pontllyfni, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical May, swells large enough to cause good for surfing waves at Pontllyfni run for about 1.0% of the time.

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