The rose diagram shows only the swells directed at Sanur Reef that coincided with light winds or offshore conditions through a typical January and is based upon 1728 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 the highest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was SW, whereas the the dominant wind blows from the WNW. 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 26% of the time, equivalent to 8 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal January but 25% of the time we expect swell in the range 2-3m (6.5-10ft) 25%, equivalent to (8 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Sanur Reef is quite sheltered from open water swells, we think that that clean surf can be found at Sanur Reef about 26% of the time and that surf is blown out by onshore wind 3% of the time. This is means that we expect 9 days with waves in a typical January, of which 8 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.