Arenillas Negras Swell Statistics, Spring: Surf with Light or Offshore Winds
This image shows only the swells directed at Arenillas Negras that coincided with light winds or offshore conditions through a typical 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 illustrates the biggest swells, greater than >3m (>10ft). In either graph, 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 longest spokes, was SW, whereas the the prevailing wind blows from the SSW. 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 10% of the time, equivalent to 9 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal southern hemisphere spring but 2% of the time we expect swell in the range 2-3m (6.5-10ft) 2%, equivalent to (2 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Arenillas Negras is exposed to open water swells, we calculate that clean surf can be found at Arenillas Negras about 10% of the time and that surf is spoilt by onshore wind 89% of the time. This is means that we expect 90 days with waves in a typical southern hemisphere spring, of which 9 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.