Aligator Rock Swell Statistics, December: All Swell – Any Wind
The rose diagram illustrates the variation of swells directed at Aligator Rock over a normal December. It is based on 2457 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the most applicable grid node based on what we know about Aligator Rock. In the case of Aligator Rock, the best grid node is 42 km away (26 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 show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These were forecast only 35% of the time. Green and yellow represent increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the dominant swell direction, shown by the longest spokes, was NNW, whereas the the most common wind blows from the E. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Aligator Rock 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 clean enough to surf at Aligator Rock, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical December, swells large enough to cause surfable waves at Aligator Rock run for about 65% 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.