The Knap Surf Stats

The figure describes the combination of swells directed at The Knap over a normal October. It is based on 3471 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the best grid node based on what we know about The Knap. In this particular case the best grid node is 50 km away (31 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 show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These happened 25% of the time. Green and yellow illustrate increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In both graphs, 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 WSW, whereas the the dominant wind blows from the SSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from The Knap and out to sea. We lump these in 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 clean enough to surf at The Knap, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical October, swells large enough to cause surfable waves at The Knap run for about 1.0% of the time.

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