Jacobs Bay Surf Stats

The rose diagram shows the variation of swells directed at Jacobs Bay over a normal July and is based upon 3720 NWW3 model predictions since 2006 (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 Jacobs Bay. In this particular case the best grid node is 37 km away (23 miles). The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These happened only 1.9% of the time. Green and yellow represent increasing swell sizes and red shows the biggest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the most common swell direction, shown by the largest spokes, was SW, whereas the the prevailing 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 Jacobs Bay and out to sea. We lump these in 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 surfable at Jacobs Bay, 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 July, swells large enough to cause good for surfing waves at Jacobs Bay run for about 98% of the time.

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