Statistiques de Houle pour Annestown, Hiver: Toutes Houles – Tous Vents
The graph shows the variation of swells directed at Annestown over a normal northern hemisphere winter. It is based on 6931 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the most applicable grid node based on what we know about Annestown, and at Annestown the best grid node is 21 km away (13 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These occurred only 31% of the time. Green and yellow represent increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the dominant swell direction, shown by the longest spokes, was SW, whereas the the prevailing wind blows from the WSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Annestown and away from the coast. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Annestown, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical northern hemisphere winter, swells large enough to cause clean enough to surf waves at Annestown run for about 43% 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.