Armadale Bay Swell Statistics, December: All Swell – Any Wind
The graph shows the combination of swells directed at Armadale Bay over a normal December, based on 2457 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 best grid node based on what we know about Armadale Bay. In this particular case the best grid node is 50 km away (31 miles).
The rose diagram illustrates 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 9% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the 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 largest spokes, was NW, whereas the the prevailing wind blows from the WSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Armadale Bay and offshore. 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 clean enough to surf at Armadale Bay, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical December, swells large enough to cause surfable waves at Armadale Bay run for about 91% 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.