Abermawr Swell Statistics, Winter: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Abermawr that coincided with light winds or offshore conditions over a normal northern hemisphere winter. It is based on 6931 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 represent increasing swell sizes and red shows highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the prevailing swell direction, shown by the longest spokes, was SW (which was the same as the dominant wind direction). 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 13% of the time, equivalent to 12 days. Open water swells exceeding >3m (>10ft) only happen 1.4% of the time in a typical northern hemisphere winter, equivalent to just one day 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 ratio of these swells that coincided with predicted offshore winds, and given the fact that Abermawr is slightly protected from open water swells, we estimate that clean surf can be found at Abermawr about 13% of the time and that surf is blown out by onshore wind 48% of the time. This is means that we expect 56 days with waves in a typical northern hemisphere winter, 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.