Arrifana Swell Statistics, April: All Swell – Any Wind
This image shows the range of swells directed at Arrifana over a normal April. It is based on 2160 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the best grid node based on what we know about Arrifana, and at Arrifana the best grid node is 26 km away (16 miles).
The rose diagram illustrates the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These occurred only 6% of the time. Green and yellow represent increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In either 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 biggest spokes, was WNW, whereas the the prevailing wind blows from the NNW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Arrifana and out to sea. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are surfable at Arrifana, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical April, swells large enough to cause good for surfing waves at Arrifana run for about 69% 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.