Hells Mouth (Porth Neigwl) Surf Stats

The rose diagram describes the variation of swells directed at Hells Mouth (Porth Neigwl) over a normal May, based on 3437 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the best grid node based on what we know about Hells Mouth (Porth Neigwl), and at Hells Mouth (Porth Neigwl) the best grid node is 36 km away (22 miles). The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These occurred 55% of the time. Green and yellow represent increasing swell sizes and red illustrates the highest swells, greater than >3m (>10ft). In each 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 longest spokes, was SW, whereas the the dominant wind blows from the WSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Hells Mouth (Porth Neigwl) and offshore. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are clean enough to surf at Hells Mouth (Porth Neigwl), you can load a different image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical May, swells large enough to cause surfable waves at Hells Mouth (Porth Neigwl) run for about 45% of the time.

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