Wet snow conditions trigger the formation of ice sleeves on overhead power lines and contribute to heavy snowfalls, which can cause severe infrastructural damage and consequently prolonged interruptions to the National Transmission Network. To develop action plans aimed at strengthening Power Network resilience, probability maps regarding ice sleeve formation and their loads on overhead power lines have been developed. Future scenarios for Italy were calculated based on 12 high-resolution Euro-CORDEX models (spatial resolution ~12 km), assuming a “Business-As-Usual” scenario (RCP8.5).

The meteorological reanalysis MERIDA (spatial resolution 4 km), covering the period 1990-2020, was used to correct model data using Extreme Value Analysis techniques. The MERIDA dataset was also utilized to implement the “Makkonen” model to describe ice sleeve growth on high-voltage lines. After validating the code by correlating results with failures recorded by the transmission network during particularly significant events, climate model outputs were used to estimate ice sleeve formation up to 2060 and derive future scenarios. Probability maps were developed using Extreme Value Analysis statistical techniques to describe expected values in twenty-year intervals centered on 2020, 2030, 2040, and 2050.

The results underscore that such phenomena are generally expected to decrease as snowfalls transition to precipitation due to global warming. However, if ice loads are expected to decrease at mid-low altitudes, these events may intensify in higher Alpine regions because, in warmer climates, temperatures between -1.0°C and +1.5°C will be more likely, thus allowing wet snow events at altitudes previously spared due to typical cold temperatures.