Ardmore Swell Statistics, Autumn: Surf with Light or Offshore Winds
This image shows only the swells directed at Ardmore that coincided with light winds or offshore conditions over a normal northern hemisphere autumn. It is based on 7252 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. Green and yellow show increasing swell sizes and red shows largest swells greater than >3m (>10ft). In each graph, 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 SW, whereas the the most common wind blows from the WSW. 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 0.3% of the time, equivalent to 0 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal northern hemisphere autumn. Taking into account the proportion of these swells that coincided with expected offshore winds, and given the fact that Ardmore is quite sheltered from open water swells, we think that that clean surf can be found at Ardmore about 0.3% of the time and that surf is spoilt by onshore wind 11% of the time. This is means that we expect 10 days with waves in a typical northern hemisphere autumn, of which 0 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.