Alkimos Swell Statistics, Setembro: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Alkimos that coincided with light winds or offshore conditions through a typical September. It is based on 2400 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 show increasing swell sizes and red represents highest 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 prevailing swell direction, shown by the biggest spokes, was WSW, whereas the the dominant wind blows from the SSW. 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 31% of the time, equivalent to 9 days. Open water swells exceeding >3m (>10ft) only arise 3% of the time in a typical September, equivalent to just one day but 10% of the time we expect swell in the range 2-3m (6.5-10ft) 10%, equivalent to (3 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Alkimos is exposed to open water swells, we calculate that clean surf can be found at Alkimos about 31% of the time and that surf is spoilt by onshore wind 69% of the time. This is means that we expect 30 days with waves in a typical September, of which 9 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.