Black Rocks Surf Stats

The figure describes the combination of swells directed at Black Rocks through a typical May. It is based on 3440 NWW3 model predictions since 2007 (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 Black Rocks, and at Black Rocks the best grid node is 23 km away (14 miles). The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 95% of the time. Green and yellow illustrate increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell was forecast. The diagram implies that the most common swell direction, shown by the longest spokes, was SSE, whereas the the dominant wind blows from the WSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Black Rocks and away from the coast. We combine 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 good for surfing at Black Rocks, you can load a different image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average May, swells large enough to cause clean enough to surf waves at Black Rocks run for about 5% of the time.

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