120th Street Surf Stats

The figure describes the variation of swells directed at 120th Street over a normal September. It is based on 2880 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the optimum grid node based on what we know about 120th Street. In this particular case the best grid node is 8 km away (5 miles). The rose diagram describes 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 were forecast only 13% of the time. Green and yellow represent increasing swell sizes and red represents the highest 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 prevailing swell direction, shown by the largest spokes, was ESE, whereas the the dominant wind blows from the NE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from 120th Street and out to sea. 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 diagram. Because wind determines whether or not waves are surfable at 120th Street, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical September, swells large enough to cause good for surfing waves at 120th Street run for about 87% of the time.

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