This image shows the combination of swells directed at Mother Ivey s Spot M through a typical March, based on 1724 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the optimum grid node based on what we know about Mother Ivey s Spot M, and at Mother Ivey s Spot M the best grid node is 35 km away (22 miles).
The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 10% of the time. Green and yellow represent increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the prevailing swell direction, shown by the longest spokes, was W, whereas the the prevailing wind blows from the WNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Mother Ivey s Spot M 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 Mother Ivey s Spot M, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average March, swells large enough to cause clean enough to surf waves at Mother Ivey s Spot M run for about 35% 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.