Ampang Swell Statistics, December: Surf with Light or Offshore Winds
This image shows only the swells directed at Ampang that coincided with light winds or offshore conditions through a typical December. It is based on 2457 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 both graphs, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was SSW, whereas the the dominant 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 40% of the time, equivalent to 12 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal December but 5% of the time we expect swell in the range 2-3m (6.5-10ft) 5%, equivalent to (2 days). Taking into account the fraction of these swells that coincided with predicted 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 40% of the time and that surf is spoilt by onshore wind 12% of the time. This is means that we expect 16 days with waves in a typical December, of which 12 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.