This chart illustrates the range of swells directed at Aberdeen Area Beach over a normal northern hemisphere spring. It is based on 5138 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the best grid node based on what we know about Aberdeen Area Beach. In this particular case the best grid node is 23 km away (14 miles).
The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing 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 happened only 82% of the time. Green and yellow show increasing swell sizes and red illustrates largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell was forecast.
The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was WSW, whereas the the most common wind blows from the W. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Aberdeen Area Beach and away from the coast. We combine these with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Aberdeen Area Beach, 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 spring, swells large enough to cause clean enough to surf waves at Aberdeen Area Beach run for about 18% 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.