Anse a La Gourde Swell Statistics, December: All Swell – Any Wind
The figure illustrates the variation of swells directed at Anse a La Gourde over a normal December and is based upon 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 Anse a La Gourde. In the case of Anse a La Gourde, the best grid node is 35 km away (22 miles).
The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 2% of the time. Green and yellow illustrate increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In either 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 biggest spokes, was NE, whereas the the most common wind blows from the ENE. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Anse a La Gourde 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 good for surfing at Anse a La Gourde, 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 Anse a La Gourde run for about 98% 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.