Airport Lefts Swell Statistics, July: Surf with Light or Offshore Winds
This image shows only the swells directed at Airport Lefts that coincided with light winds or offshore conditions through a typical July. It is based on 2480 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. Green and yellow illustrate increasing swell sizes and red illustrates the highest 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 prevailing swell direction, shown by the longest spokes, was SSW, whereas the the dominant wind blows from the ESE. 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 98% of the time, equivalent to 30 days. Open water swells exceeding >3m (>10ft) only happen 1.7% of the time in a typical July, equivalent to just one day but 69% of the time we expect swell in the range 2-3m (6.5-10ft) 69%, equivalent to (21 days). Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that Airport Lefts is exposed to open water swells, we estimate that clean surf can be found at Airport Lefts about 98% of the time and that surf is spoilt by onshore wind 1.0% of the time. This is means that we expect 31 days with waves in a typical July, of which 30 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.