Army Beach Swell Statistics, December: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Army Beach that coincided with light winds or offshore conditions over a normal December. It is based on 2457 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 represents highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell was forecast.
The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was NNW, whereas the the dominant wind blows from the E. 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 29% of the time, equivalent to 9 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal December but 13% of the time we expect swell in the range 2-3m (6.5-10ft) 13%, equivalent to (4 days). Taking into account the proportion of these swells that coincided with expected offshore winds, and given the fact that Army Beach is exposed to open water swells, we think that that clean surf can be found at Army Beach about 29% of the time and that surf is blown out by onshore wind 47% of the time. This is means that we expect 23 days with waves in a typical December, of which 9 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.