Abermawr Swell Statistics, Summer: Surf with Light or Offshore Winds
This image shows only the swells directed at Abermawr that coincided with light winds or offshore conditions over a normal northern hemisphere summer. It is based on 7266 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 represent 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 commonly that size swell occurs.
The diagram implies that the most common swell direction, shown by the biggest spokes, was SW, whereas the the prevailing wind blows from the W. 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 6% of the time, equivalent to 5 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal northern hemisphere summer but 4% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 4%, equivalent to (4 days). Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that Abermawr is slightly protected from open water swells, we calculate that clean surf can be found at Abermawr about 6% of the time and that surf is spoilt by onshore wind 22% of the time. This is means that we expect 25 days with waves in a typical northern hemisphere summer, of which 5 days should be clean enough to surf.
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.