Airport Lefts Swell Statistics, April: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Airport Lefts that coincided with light winds or offshore conditions through a typical April. It is based on 2160 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 show increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the most common 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 85% of the time, equivalent to 26 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal April but 22% of the time we expect swell in the range 2-3m (6.5-10ft) 22%, equivalent to (7 days). Taking into account the ratio of these swells that coincided with forecast 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 85% of the time and that surf is blown out by onshore wind 15% of the time. This is means that we expect 30 days with waves in a typical April, of which 26 days should be clean enough to surf.
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.