Ann Street Peaks Swell Statistics, August: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Ann Street Peaks that coincided with light winds or offshore conditions through a typical August. It is based on 2480 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 show increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the prevailing swell direction, shown by the largest spokes, was ESE, whereas the the prevailing 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 24% of the time, equivalent to 7 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal August but 5% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 5%, equivalent to (2 days). Taking into account the proportion of these swells that coincided with expected offshore winds, and given the fact that Ann Street Peaks is exposed to open water swells, we think that that clean surf can be found at Ann Street Peaks about 24% of the time and that surf is messed up by onshore wind 50% of the time. This is means that we expect 23 days with waves in a typical August, of which 7 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.