Winthrop Jetty Surf Stats

This picture illustrates the range of swells directed at Winthrop Jetty through an average July, based on 3472 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 best grid node based on what we know about Winthrop Jetty, and at Winthrop Jetty the best grid node is 41 km away (25 miles). The rose diagram illustrates 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 54% of the time. Green and yellow represent increasing swell sizes and largest 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 prevailing swell direction, shown by the largest spokes, was E, whereas the the most common wind blows from the SSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Winthrop Jetty and offshore. We combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Winthrop Jetty, 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 July, swells large enough to cause surfable waves at Winthrop Jetty run for about 46% of the time.

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