Rock Island Surf Stats

The rose diagram describes the combination of swells directed at Rock Island through an average July. It is based on 3472 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 optimum grid node based on what we know about Rock Island. In the case of Rock Island, the best grid node is 33 km away (21 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 illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 58% of the time. Green and yellow illustrate 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 happens. The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was S (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 Rock Island and offshore. We group 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 good for surfing at Rock Island, 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 July, swells large enough to cause clean enough to surf waves at Rock Island run for about 42% of the time.

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