Mouse Rock Swell Statistics, December: All Swell – Any Wind
This image shows the variation of swells directed at Mouse Rock through an average December and is based upon 2209 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the best grid node based on what we know about Mouse Rock, and at Mouse Rock the best grid node is 50 km away (31 miles).
The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing without 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 0.7% of the time. Green and yellow illustrate increasing swell sizes and red shows the biggest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the dominant swell direction, shown by the largest spokes, was WNW, whereas the the prevailing wind blows from the NNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Mouse Rock and away from the coast. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Mouse Rock, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical December, swells large enough to cause clean enough to surf waves at Mouse Rock run for about 99% 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.