Statistiques de Surf de Portsea Back Beach

This chart shows the combination of swells directed at Portsea Back Beach through an average August, based on 3590 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the best grid node based on what we know about Portsea Back Beach. In the case of Portsea Back Beach, the best grid node is 25 km away (16 miles). The rose diagram describes 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 were forecast only 7% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell occurs. The diagram indicates that the prevailing swell direction, shown by the largest spokes, was SW, whereas the the prevailing wind blows from the WNW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Portsea Back Beach 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 plot. Because wind determines whether or not waves are good for surfing at Portsea Back Beach, 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 August, swells large enough to cause clean enough to surf waves at Portsea Back Beach run for about 93% of the time.

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