Avalanche Swell Statistics, Winter: Surf with Light or Offshore Winds
This image shows only the swells directed at Avalanche that coincided with light winds or offshore conditions through a typical northern hemisphere winter. It is based on 6931 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 red illustrates the largest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the dominant swell direction, shown by the longest spokes, was NW, whereas the the most common 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 54% of the time, equivalent to 49 days. Expect open water swells to exceed >3m (>10ft) 3% of the time (3 days). Taking into account the proportion of these swells that coincided with forecast offshore winds, and given the fact that Avalanche is exposed to open water swells, we calculate that clean surf can be found at Avalanche about 54% of the time and that surf is blown out by onshore wind 29% of the time. This is means that we expect 76 days with waves in a typical northern hemisphere winter, of which 49 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.