Aberystwyth harbour trap Swell Statistics, November: Surf with Light or Offshore Winds
This image shows only the swells directed at Aberystwyth harbour trap that coincided with light winds or offshore conditions over a normal November. It is based on 2386 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 illustrate increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In either graph, 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 SW, whereas the the prevailing wind blows from the WSW. 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 4% of the time, equivalent to 1 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal November. Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Aberystwyth harbour trap is slightly protected from open water swells, we think that that clean surf can be found at Aberystwyth harbour trap about 4% of the time and that surf is messed up by onshore wind 32% of the time. This is means that we expect 11 days with waves in a typical November, of which 1 days should be surfable.
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.