Phillips Pump House Swell Statistics, May: All Swell – Any Wind
The figure shows the variation of swells directed at Phillips Pump House through a typical May. It is based on 1736 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the optimum grid node based on what we know about Phillips Pump House. In this particular case the best grid node is 28 km away (17 miles).
The rose diagram describes the distribution of swell sizes and swell direction, 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 only 16% of the time. Green and yellow show increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was SE, whereas the the prevailing wind blows from the SSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Phillips Pump House and out to sea. 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 clean enough to surf at Phillips Pump House, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average May, swells large enough to cause surfable waves at Phillips Pump House run for about 84% 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.