The following shows the difference in wind speed at 30 and 50 meters in Minnesota.
Because in the Harvestable Wind Power equation Wind Velocity is cubed a 2 meter per sec (m/s) increase will triple your kWh output.
For example 4.47m/s (10mph) to 6.47m/s (14.5mph) will make the following difference.
(6.47^3) / (4.47^3) = 3.03
Here is the equation for Wind Power.
HWP = 0.5 x 1.23 x SA x WV^3 x cP
(HWP) Harvestable Wind Power (w/hr) = 0.5 x AD (air density kg/cu m) x SA (sweep area m^2) x WV^3 (wind velocity m/s) x cP (coefficient of performance Betz limit 59.26%, R^1 or Copper loss, linear power curve to cubic curve matching — 0.25 for most systems)