Sandbox Swell Statistics, November: All Swell – Any Wind
The graph describes the combination of swells directed at Sandbox over a normal November and is based upon 2147 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 most applicable grid node based on what we know about Sandbox, and at Sandbox the best grid node is 19 km away (12 miles).
The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These happened only 63% of the time. Green and yellow show increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the most common swell direction, shown by the biggest spokes, was W, whereas the the dominant wind blows from the NNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Sandbox 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 Sandbox, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical November, swells large enough to cause clean enough to surf waves at Sandbox run for about 37% 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.