Kerlouan Swell Statistics, Summer: All Swell – Any Wind
The figure shows the combination of swells directed at Kerlouan through a typical northern hemisphere summer, based on 5802 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 Kerlouan. In the case of Kerlouan, the best grid node is 48 km away (30 miles).
The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These were forecast only 48% of the time. Green and yellow represent increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the most common swell direction, shown by the biggest spokes, was WNW, whereas the the prevailing wind blows from the W. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Kerlouan 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 plot. Because wind determines whether or not waves are surfable at Kerlouan, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average northern hemisphere summer, swells large enough to cause good for surfing waves at Kerlouan run for about 52% of the time.
IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.