Statistiques de Houle pour Acajutla, Janvier: Toutes Houles – Tous Vents

The figure describes the variation of swells directed at Acajutla through an average January and is based upon 2868 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the best grid node based on what we know about Acajutla. In this particular case the best grid node is 19 km away (12 miles).

The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened only 4% of the time. Green and yellow show increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how commonly that size swell occurs.

The diagram implies that the prevailing swell direction, shown by the largest spokes, was SSW, whereas the the dominant wind blows from the NNE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Acajutla and away from the coast. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Acajutla, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical January, swells large enough to cause surfable waves at Acajutla run for about 96% of the time.

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.