Arpoador Swell Statistics, Spring: Surf with Light or Offshore Winds
This image shows only the swells directed at Arpoador that coincided with light winds or offshore conditions over a normal southern hemisphere spring and is based upon 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 highest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the prevailing swell direction, shown by the longest spokes, was SE, whereas the the dominant wind blows from the ENE. 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 24% of the time, equivalent to 22 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal southern hemisphere spring but 4% of the time we expect swell in the range 2-3m (6.5-10ft) 4%, equivalent to (4 days). Taking into account the ratio of these swells that coincided with forecast offshore winds, and given the fact that Arpoador is slightly protected from open water swells, we calculate that clean surf can be found at Arpoador about 24% of the time and that surf is blown out by onshore wind 18% of the time. This is means that we expect 38 days with waves in a typical southern hemisphere spring, of which 22 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.