Back Bommie Surf Stats

The figure describes the variation of swells directed at Back Bommie through a typical September and is based upon 3360 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 most applicable grid node based on what we know about Back Bommie. In the case of Back Bommie, the best grid node is 9 km away (6 miles). The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but 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 only 20% of the time. Green and yellow represent increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the dominant swell direction, shown by the longest spokes, was SE, whereas the the dominant wind blows from the WNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Back Bommie and away from the coast. We combine these 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 clean enough to surf at Back Bommie, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average September, swells large enough to cause surfable waves at Back Bommie run for about 80% of the time.

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