Aligator Rock Swell Statistics, Spring: All Swell – Any Wind
This image illustrates the combination of swells directed at Aligator Rock through a typical northern hemisphere spring. It is based on 6580 NWW3 model predictions since 2007 (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 Aligator Rock. In this particular case the best grid node is 42 km away (26 miles).
The rose diagram illustrates 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 happened only 53% 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 often that size swell was forecast.
The diagram indicates that the prevailing swell direction, shown by the largest 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 combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Aligator Rock, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average northern hemisphere spring, swells large enough to cause surfable waves at Aligator Rock 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.