ADs/Doubles Swell Statistics, September: All Swell – Any Wind
The figure describes the range of swells directed at ADs/Doubles over a normal September. It is based on 2400 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the best grid node based on what we know about ADs/Doubles, and at ADs/Doubles the best grid node is 28 km away (17 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks 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 happened only 53% of the time. Green and yellow show increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In each 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 longest spokes, was ENE (which was the same as the dominant wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from ADs/Doubles 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 ADs/Doubles, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical September, swells large enough to cause good for surfing waves at ADs/Doubles run for about 47% 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.