Agate and Pearl Street Swell Statistics, September: All Swell – Any Wind
The graph illustrates the variation of swells directed at Agate and Pearl Street through an average September, based on 2400 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the optimum grid node based on what we know about Agate and Pearl Street, and at Agate and Pearl Street the best grid node is 21 km away (13 miles).
The rose diagram describes the distribution of swell directions and swell sizes, 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 87% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the dominant swell direction, shown by the largest spokes, was WSW (which was the same as the most common wind direction). Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Agate and Pearl Street and away from the coast. We group these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Agate and Pearl Street, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical September, swells large enough to cause clean enough to surf waves at Agate and Pearl Street run for about 13% 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.