Seabrook Beach Swell Statistics, All Year: All Swell – Any Wind
The figure shows the variation of swells directed at Seabrook Beach through an average year and is based upon 21624 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 Seabrook Beach. In the case of Seabrook Beach, the best grid node is 29 km away (18 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast 42% of the time. Green and yellow show increasing swell sizes and red shows the biggest swells, greater than >3m (>10ft). In either 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 largest spokes, was ESE, whereas the the prevailing wind blows from the W. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Seabrook Beach and offshore. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Seabrook Beach, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical year, swells large enough to cause clean enough to surf waves at Seabrook Beach run for about 58% 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.