Assateague Swell Statistics, May: Surf with Light or Offshore Winds
This image shows only the swells directed at Assateague that coincided with light winds or offshore conditions through a typical May. It is based on 2200 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow show increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the most common swell direction, shown by the largest spokes, was SE, whereas the the prevailing wind blows from the SSW. 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 34% of the time, equivalent to 11 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal May but 8% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 8%, equivalent to (2 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Assateague is exposed to open water swells, we think that that clean surf can be found at Assateague about 34% of the time and that surf is messed up by onshore wind 49% of the time. This is means that we expect 26 days with waves in a typical May, of which 11 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.