The rose diagram illustrates how commonly and how strongly the wind blows from different directions over a normal April. The longest spokes point in the directions the wind most commonly blows from and the shade of blue implies the strength, with the darkest shade of blue showing the strongest winds. It is based on 1630 NWW3 forecasts of wind since since 2007, at 3hr intervals, for the closest NWW3 model node to Back Bommie, located 9 km away (6 miles). There are not enough recording stations world wide to use actual wind data. No doubt some coastal places have very localized wind effects that would not be predicted by NWW3.
According to the model, the prevailing wind at Back Bommie blows from the SE. If the rose diagram shows a close to circular outline, it means there is no strong bias in wind direction at Back Bommie. By contrast, dominant spokes illustrate favoured directions, and the more deep blue, the stronger the wind. Spokes point in the direction the wind blows from. During a typical April, the model suggests that winds are light enough for the sea to be glassy (the lightest shade of blue) about 16% of the time (5 days each April) and blows offshore 31% of the time (9 days in an average April). Over an average April wind stronger than >40kph (25mph) was expected for only a single days at Back Bommie
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.