Ano Nuevo Swell Statistics, Janeiro: All Swell – Any Wind
The rose diagram shows the variation of swells directed at Ano Nuevo through an average January and is based upon 2372 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the optimum grid node based on what we know about Ano Nuevo. In this particular case the best grid node is 21 km away (13 miles).
The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened only 67% of the time. Green and yellow show increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In both graphs, 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 longest spokes, was W, whereas the the prevailing wind blows from the NNE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Ano Nuevo and out to sea. We group these 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 clean enough to surf at Ano Nuevo, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical January, swells large enough to cause surfable waves at Ano Nuevo run for about 26% 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.