Arica Swell Statistics, October: All Swell – Any Wind
The rose diagram illustrates the variation of swells directed at Arica over a normal October and is based upon 2480 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the most applicable grid node based on what we know about Arica. In this particular case the best grid node is 27 km away (17 miles).
The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 0% of the time. Green and yellow illustrate increasing swell sizes and red shows the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the most common swell direction, shown by the largest spokes, was SSW, whereas the the most common wind blows from the S. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Arica and offshore. We group these 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 good for surfing at Arica, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical October, swells large enough to cause clean enough to surf waves at Arica run for about 100% 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.