Gualala Rivermouth Surf Stats

The rose diagram describes the combination of swells directed at Gualala Rivermouth over a normal April. It is based on 3360 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 most applicable grid node based on what we know about Gualala Rivermouth. In this particular case the best grid node is 37 km away (23 miles). The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing without 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 were forecast only 73% of the time. Green and yellow illustrate increasing swell sizes and red represents the highest 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 longest spokes, was WSW, whereas the the dominant wind blows from the WNW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Gualala Rivermouth 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 Gualala Rivermouth, 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 April, swells large enough to cause surfable waves at Gualala Rivermouth run for about 27% of the time.

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