Alibaba Swell Statistics, February: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Alibaba that coincided with light winds or offshore conditions through a typical February. It is based on 2102 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow show increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was NW, whereas the the prevailing wind blows from the NE. The chart at the bottom shows the same thing but without direction information. For example, swells larger than 1.5 feet (0.5m) coincided with good wind conditions 7% of the time, equivalent to 2 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal February. Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Alibaba is exposed to open water swells, we think that that clean surf can be found at Alibaba about 7% of the time and that surf is spoilt by onshore wind 52% of the time. This is means that we expect 17 days with waves in a typical February, of which 2 days should be clean enough to surf.
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.