Anna Maria Key Swell Statistics, April: All Swell – Any Wind
The figure describes the variation of swells directed at Anna Maria Key over a normal April and is based upon 2159 NWW3 model predictions since 2007 (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 Anna Maria Key. In this particular case the best grid node is 26 km away (16 miles).
The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but 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 happened 85% of the time. Green and yellow show increasing swell sizes and red shows the highest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the dominant swell direction, shown by the largest spokes, was NW, whereas the the dominant wind blows from the E. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Anna Maria Key and offshore. We group these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Anna Maria Key, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical April, swells large enough to cause surfable waves at Anna Maria Key run for about 15% 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.