Box Beach Swell Statistics, April: All Swell – Any Wind
This picture shows the variation of swells directed at Box Beach through an average April and is based upon 2160 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the most applicable grid node based on what we know about Box Beach, and at Box Beach the best grid node is 34 km away (21 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 10% of the time. Green and yellow illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In both graphs, 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 SE, whereas the the prevailing wind blows from the S. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Box Beach and away from the coast. 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 diagram. Because wind determines whether or not waves are clean enough to surf at Box Beach, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause surfable waves at Box Beach run for about 90% 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.