Noosa - Alexandria Bay Swell Statistics, Autumn: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Noosa - Alexandria Bay that coincided with light winds or offshore conditions over a normal southern hemisphere autumn. It is based on 6580 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 largest swells greater than >3m (>10ft) are shown in red. In either graph, 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 SSE, whereas the the most common wind blows from the SE. 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 4 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal southern hemisphere autumn. Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Noosa - Alexandria Bay is exposed to open water swells, we calculate that clean surf can be found at Noosa - Alexandria Bay about 4% of the time and that surf is spoilt by onshore wind 23% of the time. This is means that we expect 25 days with waves in a typical southern hemisphere autumn, of which 4 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.