The rose diagram illustrates the range of swells directed at Cortegaca through an average March. It is based on 1724 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the optimum grid node based on what we know about Cortegaca. In the case of Cortegaca, the best grid node is 30 km away (19 miles).
The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing without 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 4% of the time. Green and yellow represent increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was WNW, whereas the the most common wind blows from the N. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Cortegaca and away from the coast. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are surfable at Cortegaca, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical March, swells large enough to cause good for surfing waves at Cortegaca run for about 96% 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.