Andrew Molera State Park Swell Statistics, Aprile: Surf with Light or Offshore Winds
This image shows only the swells directed at Andrew Molera State Park that coincided with light winds or offshore conditions through a typical April. It is based on 2160 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 illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the dominant swell direction, shown by the longest spokes, was WNW, whereas the the prevailing wind blows from the NW. 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 27% of the time, equivalent to 8 days. Open water swells exceeding >3m (>10ft) only occur 2% of the time in a typical April, equivalent to just one day but 14% of the time we expect swell in the range 2-3m (6.5-10ft) 14%, equivalent to (4 days). Taking into account the fraction of these swells that coincided with expected offshore winds, and given the fact that Andrew Molera State Park is exposed to open water swells, we calculate that clean surf can be found at Andrew Molera State Park about 27% of the time and that surf is blown out by onshore wind 63% of the time. This is means that we expect 27 days with waves in a typical April, of which 8 days should be clean enough to surf.
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.