Arugam Bay Swell Statistics, May: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Arugam Bay that coincided with light winds or offshore conditions through a typical 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 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 biggest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the dominant swell direction, shown by the longest spokes, was S, whereas the the prevailing wind blows from the SW. 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 3% of the time, equivalent to 1 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal May. Taking into account the ratio of these swells that coincided with forecast offshore winds, and given the fact that Arugam Bay is exposed to open water swells, we calculate that clean surf can be found at Arugam Bay about 3% of the time and that surf is messed up by onshore wind 97% of the time. This is means that we expect 31 days with waves in a typical May, of which 1 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.