This chart describes the variation of swells directed at Norderney over a normal September. It is based on 1677 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 optimum grid node based on what we know about Norderney. In this particular case the best grid node is 33 km away (21 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 show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 50% of the time. Green and yellow represent increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the dominant swell direction, shown by the largest spokes, was NW, whereas the the dominant wind blows from the WSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Norderney and out to sea. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are surfable at Norderney, 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 September, swells large enough to cause good for surfing waves at Norderney run for about 50% 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.