Arrieta Swell Statistics, Novembro: Surf with Light or Offshore Winds
This image shows only the swells directed at Arrieta that coincided with light winds or offshore conditions over a normal November and is based upon 2387 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 each graph, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was NNW, whereas the the most common wind blows from the NNE. 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 11% of the time, equivalent to 3 days. Open water swells exceeding >3m (>10ft) only happen 3% of the time in a typical November, equivalent to just one day but 8% of the time we expect swell in the range 2-3m (6.5-10ft) 8%, equivalent to (2 days). Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that Arrieta is quite sheltered from open water swells, we calculate that clean surf can be found at Arrieta about 11% of the time and that surf is spoilt by onshore wind 31% of the time. This is means that we expect 13 days with waves in a typical November, of which 3 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.