Aligator Rock Swell Statistics, May: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Aligator Rock that coincided with light winds or offshore conditions over a normal May. It is based on 2200 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow illustrate increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the most common swell direction, shown by the largest spokes, was NNW, whereas the the dominant wind blows from the E. 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 33% of the time, equivalent to 10 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal May but 7% of the time we expect swell in the range 2-3m (6.5-10ft) 7%, equivalent to (2 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Aligator Rock is exposed to open water swells, we estimate that clean surf can be found at Aligator Rock about 33% of the time and that surf is messed up by onshore wind 4% of the time. This is means that we expect 11 days with waves in a typical May, of which 10 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.