Asu Swell Statistics, March: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Asu that coincided with light winds or offshore conditions through a typical March. It is based on 2220 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 represent increasing swell sizes and red shows the largest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was SSW, whereas the the most common wind blows from the WSW. 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 66% of the time, equivalent to 20 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal March but 37% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 37%, equivalent to (11 days). Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that Asu is exposed to open water swells, we estimate that clean surf can be found at Asu about 66% of the time and that surf is messed up by onshore wind 34% of the time. This is means that we expect 31 days with waves in a typical March, of which 20 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.