Mangersta Sands (Lewis) Surf Stats

The figure illustrates the variation of swells directed at Mangersta Sands (Lewis) through a typical July, based on 3472 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the optimum grid node based on what we know about Mangersta Sands (Lewis). In the case of Mangersta Sands (Lewis), the best grid node is 19 km away (12 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 25% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the dominant swell direction, shown by the biggest spokes, was W, whereas the the most common wind blows from the SW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Mangersta Sands (Lewis) and offshore. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Mangersta Sands (Lewis), you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average July, swells large enough to cause clean enough to surf waves at Mangersta Sands (Lewis) run for about 75% of the time.

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