Playa de San Lorenzo Swell Statistics, Autumn: All Swell – Any Wind
This image describes the variation of swells directed at Playa de San Lorenzo through a typical northern hemisphere autumn. It is based on 6516 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 best grid node based on what we know about Playa de San Lorenzo. In the case of Playa de San Lorenzo, the best grid node is 53 km away (33 miles).
The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 9% of the time. Green and yellow represent increasing swell sizes and red represents highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was NW, whereas the the dominant wind blows from the N. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Playa de San Lorenzo and offshore. 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 surfable at Playa de San Lorenzo, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average northern hemisphere autumn, swells large enough to cause good for surfing waves at Playa de San Lorenzo run for about 75% of the time.
IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.