Ala Moana Swell Statistics, July: All Swell – Any Wind
This image illustrates the range of swells directed at Ala Moana through a typical July and is based upon 2480 NWW3 model predictions since 2006 (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 Ala Moana, and at Ala Moana the best grid node is 39 km away (24 miles).
The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing 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 0% of the time. Green and yellow show increasing swell sizes and red shows the largest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the most common swell direction, shown by the longest spokes, was SSW, whereas the the most common wind blows from the S. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Ala Moana and offshore. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Ala Moana, 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 July, swells large enough to cause clean enough to surf waves at Ala Moana run for about 100% 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.