Extreme windstorm hazard in northern Italy using non-asymptotic statistics

As recently shown by the storm Vaia that hit Northeastern Italy in the fall of 2018, extreme wind represents a critical weather-related hazard in this region. Over the course of this century, changes in the frequency of extreme windstorms are expected. Obtaining an accurate understanding of wind speed distribution in present and future conditions is thus vital. Robust estimates of the probability of occurrence of extreme winds must be developed and employed to save lives and reduce economic losses. The objective of this study is to develop a novel non-asymptotic statistical method to estimate extreme wind return levels at multiple temporal scales (wind gusts, hourly, daily). Our approach is based on the identification of independent wind storms and estimation of ordinary wind speed events, the latter defined over the Veneto region using multi-year observations from 146 stations. To model the cumulative distribution function of ordinary wind speed events, different parametric distributions are compared, including mixture models specifications. By separately considering storm occurrence and conditional wind speed intensity, the proposed method could improve our understanding of wind speed extremes in the area and provides a tool for projecting future extreme wind speed return levels based on available model simulations.