Long Beach Swell Statistics, Spring: All Swell – Any Wind
This image describes the combination of swells directed at Long Beach through a typical northern hemisphere spring and is based upon 5140 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 best grid node based on what we know about Long Beach. In this particular case the best grid node is 46 km away (29 miles).
The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 50% of the time. Green and yellow represent increasing swell sizes and red shows 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 prevailing swell direction, shown by the longest spokes, was S, whereas the the dominant wind blows from the SSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Long Beach 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 diagram. Because wind determines whether or not waves are good for surfing at Long Beach, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average northern hemisphere spring, swells large enough to cause clean enough to surf waves at Long Beach run for about 50% 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.