Balephetrish (Tiree) Swell Statistics, November: All Swell – Any Wind
This image shows the range of swells directed at Balephetrish (Tiree) through an average November. It is based on 2147 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the most applicable 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 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 23% of the time. Green and yellow show increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the most common swell direction, shown by the longest spokes, was WNW, whereas the the prevailing wind blows from the SW. 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 group these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Balephetrish (Tiree), 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 November, swells large enough to cause surfable waves at Balephetrish (Tiree) run for about 77% 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.