Black Rock Surf Stats

The graph shows the combination of swells directed at Black Rock through an average May. It is based on 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the best grid node based on what we know about Black Rock. In the case of Black Rock, the best grid node is 23 km away (14 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing 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 40% of the time. Green and yellow illustrate increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In both graphs, 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 biggest spokes, was WSW, whereas the the prevailing wind blows from the W. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Black Rock and offshore. We combine these 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 view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical May, swells large enough to cause good for surfing waves at Black Rock run for about 14% of the time.

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