Black Rocks Surf Stats

This image describes the variation of swells directed at Black Rocks through a typical April. It is based on 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the most applicable grid node based on what we know about Black Rocks, and at Black Rocks the best grid node is 35 km away (22 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 were forecast only 22% of the time. Green and yellow illustrate increasing swell sizes and red represents highest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell occurs. The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was WNW, whereas the the dominant wind blows from the SSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Black Rocks and offshore. 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 clean enough to surf at Black Rocks, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average April, swells large enough to cause surfable waves at Black Rocks run for about 78% of the time.

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