Ahu Ahu Road Swell Statistics, Winter: 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 through a typical southern hemisphere winter. 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 red represents biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell was forecast.
The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was WSW, whereas the the prevailing 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 33% of the time, equivalent to 30 days. Open water swells exceeding >3m (>10ft) only occur 0.6% of the time in a typical southern hemisphere winter, equivalent to just one day but 8% of the time we expect swell in the range 2-3m (6.5-10ft) 8%, equivalent to (7 days). Taking into account the fraction of these swells that coincided with forecast offshore winds, and given the fact that Ahu Ahu Road is exposed to open water swells, we calculate that clean surf can be found at Ahu Ahu Road about 33% of the time and that surf is blown out by onshore wind 54% of the time. This is means that we expect 79 days with waves in a typical southern hemisphere winter, of which 30 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.