Black Rock Surf Stats

This chart illustrates the variation of swells directed at Black Rock over a normal 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 coast so we have chosen the most applicable grid node based on what we know about Black Rock. In the case of Black Rock, the best grid node is 44 km away (27 miles). The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These happened only 61% of the time. Green and yellow show increasing swell sizes and red represents largest 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 dominant swell direction, shown by the longest spokes, was ENE, whereas the the most common wind blows from the SE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Black Rock and away from the coast. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Black Rock, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical April, swells large enough to cause clean enough to surf waves at Black Rock run for about 39% of the time.

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