Avalanche Swell Statistics, Janeiro: Surf with Light or Offshore Winds
This image shows only the swells directed at Avalanche that coincided with light winds or offshore conditions over a normal January and is based upon 2372 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 shows biggest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the most common swell direction, shown by the largest spokes, was NW, whereas the the prevailing wind blows from the ENE. 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 49% of the time, equivalent to 15 days. Open water swells exceeding >3m (>10ft) only arise 4% of the time in a typical January, equivalent to just one day but 26% of the time we expect swell in the range 2-3m (6.5-10ft) 26%, equivalent to (8 days). Taking into account the ratio of these swells that coincided with forecast offshore winds, and given the fact that Avalanche is exposed to open water swells, we think that that clean surf can be found at Avalanche about 49% of the time and that surf is blown out by onshore wind 39% of the time. This is means that we expect 27 days with waves in a typical January, of which 15 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.