Black Rock Surf Stats

The graph describes the combination of swells directed at Black Rock through an average April, based on 3359 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 optimum grid node based on what we know about Black Rock. In this particular case the best grid node is 23 km away (14 miles). The rose diagram shows the distribution of swell directions and swell sizes, 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 happened 39% of the time. Green and yellow represent increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how frequently that size swell was forecast. The diagram suggests that the dominant swell direction, shown by the longest spokes, was WSW, whereas the the dominant 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 lump these in with the no surf category of the bar chart. To keep it simple we don't show these in the rose graph. Because wind determines whether or not waves are surfable at Black Rock, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause good for surfing waves at Black Rock run for about 14% of the time.

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