Arenillas Negras Swell Statistics, December: All Swell – Any Wind
This picture shows the range of swells directed at Arenillas Negras over a normal December, based on 2457 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the most applicable grid node based on what we know about Arenillas Negras, and at Arenillas Negras the best grid node is 19 km away (12 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 illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened only 0.4% of the time. Green and yellow represent increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the most common swell direction, shown by the biggest spokes, was SW, whereas the the prevailing wind blows from the SSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Arenillas Negras and away from the coast. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Arenillas Negras, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical December, swells large enough to cause clean enough to surf waves at Arenillas Negras 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.