Batu Mandi Swell Statistics, February: All Swell – Any Wind
This chart describes the range of swells directed at Batu Mandi over a normal February and is based upon 2032 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 Batu Mandi. In this particular case the best grid node is 35 km away (22 miles).
The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without 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 were forecast only 9% of the time. Green and yellow represent increasing swell sizes and red illustrates highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was SSW, whereas the the dominant wind blows from the W. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Batu Mandi and out to sea. We combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are surfable at Batu Mandi, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical February, swells large enough to cause good for surfing waves at Batu Mandi run for about 91% 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.