Avalon Pier Swell Statistics, April: Surf with Light or Offshore Winds
This image shows only the swells directed at Avalon Pier that coincided with light winds or offshore conditions over a normal April and is based upon 2160 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 show increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the most common swell direction, shown by the longest spokes, was ENE, whereas the the most common wind blows from the W. 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 15% of the time, equivalent to 4 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal April. Taking into account the proportion of these swells that coincided with expected offshore winds, and given the fact that Avalon Pier is exposed to open water swells, we estimate that clean surf can be found at Avalon Pier about 15% of the time and that surf is spoilt by onshore wind 38% of the time. This is means that we expect 16 days with waves in a typical April, of which 4 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.