We study the efficiency of a torsional-flutter energy harvester in non-synoptic windNon-synoptic wind environments. The apparatus has been proposed as an alternative to other flapping mills of medium size. The study is inspired by Professor Solari’s work that examines the dynamic response of structures due to non-stationary, turbulent thunderstormThunderstorm outflowsThunderstorm outflows. A sudden change of wind loadWind loads intensity during a thunderstormThunderstorm may either impact energy conversion or damage the apparatus. A stochastic model is used to investigate both pre-critical and post-critical regimes, influenced by non-stationary turbulenceTurbulence. The model also includes aeroelastic load variability through suitable random perturbation to the unsteady Wagner’s indicial function. Various geometries of the apparatus are considered: variable width of the blade-airfoil, aspect ratio (transverse length to chord), etc. The study describes recent numerical results and shows that unsteady turbulenceTurbulence has a detrimental effect on the performance and the instability onset. This paper was completed in 2024 while L. Caracoglia was on sabbatical leave and a Visiting Professor in the Department of Civil, Environmental and Mechanical Engineering of the University of Trento (Italy).