Generation of average wind speed for the dynamic speed ranges is currently calculated over the entire period selected for the wind rose.
Might it be a good idea to have an additional option, for example 'hours_for_average' to generate the average speed that creates your speed range for the bar?
As an example, you might want the rose to show data for 12 hours, but the bar to be generated relative to the average over a 2 hours period when a wind storm blows through?