Winthrop Jetty Surf Stats

This image illustrates the variation of swells directed at Winthrop Jetty over a normal June and is based upon 3384 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the most applicable grid node based on what we know about Winthrop Jetty. In the case of Winthrop Jetty, the best grid node is 41 km away (25 miles). The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast 48% 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 commonly that size swell happens. The diagram implies that the prevailing swell direction, shown by the longest spokes, was E, whereas the the most common wind blows from the SSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Winthrop Jetty and out to sea. 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 good for surfing at Winthrop Jetty, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical June, swells large enough to cause clean enough to surf waves at Winthrop Jetty run for about 52% of the time.

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