The rose diagram illustrates how frequently and how strongly the wind blows from different directions over a normal southern hemisphere summer. The largest spokes point in the directions the wind most commonly blows from and the shade of blue indicates the strength, with the darkest shade of blue showing the strongest winds. It is based on 5048 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Cartagena, located 32 km away (20 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 dominant wind at Cartagena blows from the SW. If the rose graph shows a fairly circular pattern, it means there is no strong bias in wind direction at Cartagena. By contrast, dominant spokes show favoured directions, and the more dark blue, the stronger the wind. Spokes point in the direction the wind blows from. During a typical southern hemisphere summer, the model suggests that winds are light enough for the sea to be glassy (pale blue) about 11% of the time (10 days each southern hemisphere summer) and blows offshore 11% of the time (10 days in an average southern hemisphere summer). Over an average southern hemisphere summer winds stronger than >40kph (25mph) are expected on 7 days at Cartagena
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.