Arugam Bay Swell Statistics, Winter: All Swell – Any Wind
This chart shows the combination of swells directed at Arugam Bay over a normal northern hemisphere winter and is based upon 6931 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the most applicable grid node based on what we know about Arugam Bay. 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 without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 42% of the time. Green and yellow show increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was S, whereas the the prevailing wind blows from the NNE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Arugam Bay and out to sea. We lump these in 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 surfable at Arugam Bay, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical northern hemisphere winter, swells large enough to cause good for surfing waves at Arugam Bay run for about 58% 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.