Trecco Bay Swell Statistics, Spring: All Swell – Any Wind
The figure illustrates the combination of swells directed at Trecco Bay through an average northern hemisphere spring and is based upon 5801 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 best grid node based on what we know about Trecco Bay, and at Trecco Bay the best grid node is 22 km away (14 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These occurred 36% of the time. Green and yellow illustrate increasing swell sizes and red shows largest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the prevailing swell direction, shown by the biggest spokes, was WSW, whereas the the most common wind blows from the W. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Trecco Bay and away from the coast. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Trecco Bay, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical northern hemisphere spring, swells large enough to cause surfable waves at Trecco Bay run for about 19% 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.