Alkimos Swell Statistics, Autumn: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Alkimos that coincided with light winds or offshore conditions through a typical southern hemisphere autumn. It is based on 6580 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow represent increasing swell sizes and red shows the largest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was SW, whereas the the most common wind blows from the SSE. 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 42% of the time, equivalent to 38 days. Open water swells exceeding >3m (>10ft) only happen 1.0% of the time in a typical southern hemisphere autumn, equivalent to just one day but 9% of the time we expect swell in the range 2-3m (6.5-10ft) 9%, equivalent to (8 days). Taking into account the proportion of these swells that coincided with expected offshore winds, and given the fact that Alkimos is exposed to open water swells, we estimate that clean surf can be found at Alkimos about 42% of the time and that surf is spoilt by onshore wind 58% of the time. This is means that we expect 91 days with waves in a typical southern hemisphere autumn, of which 38 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.