Prediction: Increase in Thunder Showers

In a recent study published in "Science Advances", researchers from the University of Bern and ETH Zurich have predicted an increase in severe thunderstorms, known as supercell thunderstorms, across Europe due to climate change.

The study, which simulated the frequency of supercell-like thunderstorms in Switzerland and other parts of Europe, revealed that a 3°C warming would significantly increase these storms, particularly in the Alpine region. The researchers used Earth system models with a resolution of 50 kilometers and 95 vertical layers to conduct their study.

However, it's important to note that these thunderstorm cells, although they can occur in groups, typically have a diameter of only a few kilometers and are not yet detectable by climate models.

Last week, heavy rainfall in Italy affected various regions, causing numerous trees to be uprooted, houses to be damaged, and landslides to occur. Particularly large hailstones of mostly two to three centimeters in diameter were reported from the central and southern Italian regions of Umbria, Abruzzo, Molise, and Puglia. The largest hailstone, with a diameter of nearly ten centimeters, was reported from the village of Guglionesi in the Molise region.

The intense and destructive hail is an indication that some of the rainfall was associated with so-called supercells, meaning particularly severe thunderstorms. The simulation results showed slightly less intense thunderstorms than actually occurred, according to co-author Monika Feldmann.

The accuracy and reliability of weather forecast models depend on the grid resolution and the size of the time steps, with smaller being better, but limited by computing power. In the past, most global models for the Intergovernmental Panel on Climate Change (IPCC) were calculated with a resolution of approximately 200 by 200 kilometers. The study, however, simulated the frequency of supercell thunderstorms in Europe with a resolution of 2.2 kilometers.

The study also suggests that more crop and weather damage can be expected in southern Germany in the future due to an increase in supercell thunderstorms. Parts of Switzerland, Slovenia, and France were also affected, with several wind funnels or tornadoes reported.

The study compared the simulated frequency of supercell thunderstorms under current conditions with European weather data from 2016 to 2021. The number of supercell thunderstorms could increase by up to 52 percent, particularly on the north side of the Alps.

This new study predicts an increase in these particularly severe weather events in a warming world, emphasizing the need for continued research and preparedness in the face of climate change.