Armadale Bay Swell Statistics, September: Surf with Light or Offshore Winds
This image shows only the swells directed at Armadale Bay that coincided with light winds or offshore conditions over a normal September and is based upon 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 represent increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell was forecast.
The diagram suggests that the dominant swell direction, shown by the largest spokes, was WNW, whereas the the prevailing wind blows from the SW. 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 44% of the time, equivalent to 13 days. Open water swells exceeding >3m (>10ft) only occur 1.8% of the time in a typical September, equivalent to just one day but 13% of the time we expect swell in the range 2-3m (6.5-10ft) 13%, equivalent to (4 days). Taking into account the proportion of these swells that coincided with predicted offshore winds, and given the fact that Armadale Bay is exposed to open water swells, we estimate that clean surf can be found at Armadale Bay about 44% of the time and that surf is messed up by onshore wind 46% of the time. This is means that we expect 27 days with waves in a typical September, of which 13 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.