Balephetrish (Tiree) Swell Statistics, November: All Swell – Any Wind
The graph describes the combination of swells directed at Balephetrish (Tiree) over a normal November, based on 2387 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the optimum grid node based on what we know about Balephetrish (Tiree). In the case of Balephetrish (Tiree), the best grid node is 8 km away (5 miles).
The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but 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 22% of the time. Green and yellow illustrate increasing swell sizes and highest 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 happens.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was WNW, whereas the the dominant wind blows from the WSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Balephetrish (Tiree) and out to sea. We lump these in 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 Balephetrish (Tiree), you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical November, swells large enough to cause clean enough to surf waves at Balephetrish (Tiree) run for about 78% 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.