Postollonec Surf Stats

The rose diagram illustrates the variation of swells directed at Postollonec through an average September and is based upon 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the most applicable grid node based on what we know about Postollonec. In this particular case 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 but lacks direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These happened only 6% of the time. Green and yellow represent increasing swell sizes and red shows the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the prevailing swell direction, shown by the largest spokes, was W, whereas the the most common wind blows from the WNW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Postollonec and out to sea. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose diagram. Because wind determines whether or not waves are clean enough to surf at Postollonec, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical September, swells large enough to cause surfable waves at Postollonec run for about 6% of the time.

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