Ampang Swell Statistics, Spring: Surf with Light or Offshore Winds
This image shows only the swells directed at Ampang that coincided with light winds or offshore conditions over a normal southern hemisphere spring. It is based on 7252 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 red shows biggest swells greater than >3m (>10ft). 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 largest spokes, was SSW, whereas the the prevailing wind blows from the S. 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 22% of the time, equivalent to 20 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal southern hemisphere spring but 6% of the time we expect swell in the range 2-3m (6.5-10ft) 6%, equivalent to (5 days). Taking into account the proportion of these swells that coincided with forecast offshore winds, and given the fact that Ampang is slightly protected from open water swells, we estimate that clean surf can be found at Ampang about 22% of the time and that surf is spoilt by onshore wind 42% of the time. This is means that we expect 58 days with waves in a typical southern hemisphere spring, of which 20 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.