Statistiques de Houle pour Ampang, Hiver: Toutes Houles – Tous Vents
This picture describes the combination of swells directed at Ampang through a typical southern hemisphere winter, based on 7266 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the most applicable grid node based on what we know about Ampang, and at Ampang the best grid node is 14 km away (9 miles).
The rose diagram shows the distribution of swell directions and swell sizes, 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 occurred only 33% of the time. Green and yellow represent increasing swell sizes and red illustrates the highest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the dominant swell direction, shown by the biggest spokes, was SSW, whereas the the dominant wind blows from the ESE. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Ampang and offshore. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose plot. Because wind determines whether or not waves are surfable at Ampang, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average southern hemisphere winter, swells large enough to cause good for surfing waves at Ampang run for about 65% 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.