Aberystwyth harbour trap Swell Statistics, Spring: All Swell – Any Wind
The rose diagram illustrates the variation of swells directed at Aberystwyth harbour trap through an average northern hemisphere spring and is based upon 6577 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the optimum grid node based on what we know about Aberystwyth harbour trap. In this particular case the best grid node is 29 km away (18 miles).
The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but 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 happened 53% of the time. Green and yellow represent increasing swell sizes and red represents largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the most common swell direction, shown by the biggest spokes, was WSW (which was the same as the most common wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Aberystwyth harbour trap and offshore. We combine these 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 good for surfing at Aberystwyth harbour trap, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical northern hemisphere spring, swells large enough to cause clean enough to surf waves at Aberystwyth harbour trap run for about 17% 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.