This chart illustrates the variation of swells directed at LancesLeft through an average January and is based upon 1728 NWW3 model predictions since 2007 (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 LancesLeft. In this particular case the best grid node is 21 km away (13 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 show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These happened only 0.3% of the time. Green and yellow represent increasing swell sizes and red represents largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was SW, whereas the the most common wind blows from the NW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from LancesLeft 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 plot. Because wind determines whether or not waves are surfable at LancesLeft, 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 January, swells large enough to cause good for surfing waves at LancesLeft run for about 100% 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.