Aberystwyth harbour trap Swell Statistics, Spring: Surf with Light or Offshore Winds
This image shows only the swells directed at Aberystwyth harbour trap that coincided with light winds or offshore conditions over a normal northern hemisphere spring. It is based on 6577 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow illustrate increasing swell sizes and red shows the 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 SW (which was the same as the most common wind direction). The chart at the bottom shows the same thing but without direction information. For example, swells larger than 1.5 feet (0.5m) coincided with good wind conditions 1.4% of the time, equivalent to 1 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal northern hemisphere spring. Taking into account the proportion of these swells that coincided with forecast offshore winds, and given the fact that Aberystwyth harbour trap is slightly protected from open water swells, we estimate that clean surf can be found at Aberystwyth harbour trap about 1.4% of the time and that surf is spoilt by onshore wind 16% of the time. This is means that we expect 15 days with waves in a typical northern hemisphere spring, of which 1 days should be surfable.
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.