Moonlight Beach Swell Statistics, Autumn: All Swell – Any Wind
The figure describes the combination of swells directed at Moonlight Beach through an average northern hemisphere autumn and is based upon 5829 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the most applicable grid node based on what we know about Moonlight Beach. In the case of Moonlight Beach, the best grid node is 20 km away (12 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 represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast only 8% of the time. Green and yellow illustrate increasing swell sizes and red shows the highest 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 longest spokes, was SW, whereas the the dominant wind blows from the WNW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Moonlight Beach and offshore. We combine 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 clean enough to surf at Moonlight Beach, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical northern hemisphere autumn, swells large enough to cause surfable waves at Moonlight Beach run for about 92% 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.