Southend Reef Swell Statistics, October: All Swell – Any Wind
The graph illustrates the combination of swells directed at Southend Reef through an average October, based on 1984 NWW3 model predictions since 2008 (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 Southend Reef. In the case of Southend Reef, the best grid node is 32 km away (20 miles).
The rose diagram describes the distribution of swell sizes and swell direction, 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 happened only 67% of the time. Green and yellow represent increasing swell sizes and red shows largest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the prevailing swell direction, shown by the biggest spokes, was S, whereas the the most common wind blows from the SW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Southend Reef 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 diagram. Because wind determines whether or not waves are good for surfing at Southend Reef, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical October, swells large enough to cause clean enough to surf waves at Southend Reef run for about 33% 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.