Kanaha Swell Statistics, April: Surf with Light or Offshore Winds
This image shows only the swells directed at Kanaha that coincided with light winds or offshore conditions through a typical April and is based upon 1920 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 represents the highest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the dominant swell direction, shown by the longest spokes, was NNE, whereas the the dominant wind blows from the E. 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 41% of the time, equivalent to 12 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal April but 16% of the time we expect swell in the range 2-3m (6.5-10ft) 16%, equivalent to (5 days). Taking into account the proportion of these swells that coincided with expected offshore winds we calculate that clean surf can be found at Kanaha about 41% of the time and that surf is spoilt by onshore wind 18% of the time. This is means that we expect 18 days with waves in a typical April, of which 12 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.