Slaughterhouse Swell Statistics, All Year: All Swell – Any Wind
The graph shows the variation of swells directed at Slaughterhouse through a typical year and is based upon 21628 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the best grid node based on what we know about Slaughterhouse. In this particular case the best grid node is 15 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 without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened only 48% of the time. Green and yellow represent increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In both graphs, 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 longest spokes, was N, whereas the the prevailing wind blows from the E. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Slaughterhouse and away from the coast. We group 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 Slaughterhouse, you can load a different image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average year, swells large enough to cause good for surfing waves at Slaughterhouse run for about 52% 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.