Aligator Rock Swell Statistics, October: 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 through a typical October. 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 illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow show increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was NNW, whereas the the prevailing 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 53% of the time, equivalent to 16 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal October but 31% of the time we expect swell in the range 2-3m (6.5-10ft) 31%, equivalent to (10 days). Taking into account the proportion of these swells that coincided with forecast offshore winds, and given the fact that Aligator Rock is exposed to open water swells, we calculate that clean surf can be found at Aligator Rock about 53% of the time and that surf is messed up by onshore wind 5% of the time. This is means that we expect 18 days with waves in a typical October, of which 16 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.