Statistiques de Houle pour Arica, Automne: Vagues avec Vents Légers ou Favorables.
This image shows only the swells directed at Arica that coincided with light winds or offshore conditions through a typical southern hemisphere autumn and is based upon 6580 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 biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the most common swell direction, shown by the largest spokes, was SSW, whereas the the prevailing wind blows from the S. 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 8% of the time, equivalent to 7 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal southern hemisphere autumn but 3% of the time we expect swell in the range 2-3m (6.5-10ft) 3%, equivalent to (3 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Arica is exposed to open water swells, we calculate that clean surf can be found at Arica about 8% of the time and that surf is blown out by onshore wind 92% of the time. This is means that we expect 91 days with waves in a typical southern hemisphere autumn, of which 7 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.