Balephetrish (Tiree) Swell Statistics, May: All Swell – Any Wind
This image shows the range of swells directed at Balephetrish (Tiree) through an average May, based on 2200 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 best 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 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 29% of the time. Green and yellow show increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the most common swell direction, shown by the biggest spokes, was WNW, whereas the the prevailing 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 combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. 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. In a typical May, swells large enough to cause clean enough to surf waves at Balephetrish (Tiree) run for about 71% 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.