This image shows only the swells directed at Generals that coincided with light winds or offshore conditions through a typical northern hemisphere winter and is based upon 5048 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 represent increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the most common swell direction, shown by the biggest spokes, was WNW, whereas the the dominant wind blows from the NW. 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 23% of the time, equivalent to 21 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal northern hemisphere winter but 12% of the time we expect swell in the range 2-3m (6.5-10ft) 12%, equivalent to (11 days). Taking into account the fraction of these swells that coincided with forecast offshore winds, and given the fact that Generals is slightly protected from open water swells, we think that that clean surf can be found at Generals about 23% of the time and that surf is spoilt by onshore wind 12% of the time. This is means that we expect 32 days with waves in a typical northern hemisphere winter, of which 21 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.