Ahu Ahu Road Swell Statistics, Spring: Surf with Light or Offshore Winds
This image shows only the swells directed at Ahu Ahu Road that coincided with light winds or offshore conditions over a normal southern hemisphere spring. 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 illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow represent increasing swell sizes and red represents highest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was WSW, whereas the the dominant 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 22% of the time, equivalent to 20 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal southern hemisphere spring but 5% of the time we expect swell in the range 2-3m (6.5-10ft) 5%, equivalent to (5 days). Taking into account the fraction of these swells that coincided with expected offshore winds, and given the fact that Ahu Ahu Road is exposed to open water swells, we think that that clean surf can be found at Ahu Ahu Road about 22% of the time and that surf is messed up by onshore wind 71% of the time. This is means that we expect 85 days with waves in a typical southern hemisphere spring, of which 20 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.