Statistiques de Surf de Portao

The graph shows the range of swells directed at Portao through a typical August, based on 3590 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 Portao, and at Portao the best grid node is 24 km away (15 miles). The rose diagram describes the distribution of swell sizes and swell direction, 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 were forecast only 77% of the time. Green and yellow show increasing swell sizes and biggest 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 most common swell direction, shown by the longest spokes, was NE, whereas the the prevailing wind blows from the ESE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Portao and away from the coast. We lump these in 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 surfable at Portao, 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 August, swells large enough to cause good for surfing waves at Portao run for about 23% of the time.

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