Aticama Swell Statistics, Winter: Surf with Light or Offshore Winds
This image shows only the swells directed at Aticama that coincided with light winds or offshore conditions over a normal northern hemisphere winter. It is based on 6931 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 illustrate increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the prevailing swell direction, shown by the longest spokes, was SW, whereas the the dominant wind blows from the N. 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 30% of the time, equivalent to 27 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal northern hemisphere winter but 6% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 6%, equivalent to (5 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Aticama is exposed to open water swells, we think that that clean surf can be found at Aticama about 30% of the time and that surf is messed up by onshore wind 9% of the time. This is means that we expect 35 days with waves in a typical northern hemisphere winter, of which 27 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.