series.windbarb.softThreshold

When this is true, the series will not cause the Y axis to cross the zero plane (or threshold option) unless the data actually crosses the plane.

For example, if softThreshold is false, a series of 0, 1, 2, 3 will make the Y axis show negative values according to the minPadding option. If softThreshold is true, the Y axis starts at 0.