Asu Swell Statistics, Janeiro: Surf with Light or Offshore Winds
This image shows only the swells directed at Asu that coincided with light winds or offshore conditions through a typical January. It is based on 2372 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. Green and yellow illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In either 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 biggest spokes, was SSW, whereas the the prevailing wind blows from the WSW. 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 69% of the time, equivalent to 21 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal January but 31% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 31%, equivalent to (10 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that Asu is exposed to open water swells, we think that that clean surf can be found at Asu about 69% of the time and that surf is blown out by onshore wind 31% of the time. This is means that we expect 31 days with waves in a typical January, of which 21 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.