The weather is going crazy in Switzerland these days. Hardly a day without a place being devastated by the forces of nature. The worst hit on Tuesday evening in Cressier NE: After heavy storms, a boulder plowed its way through the village between Lake Biel and Lake Neuchâtel (Blick reported).
75 buildings are affected by the storm, residents speak of a nightmare. Insurance experts suspect property damage of around 15 million francs in the affected region.
Locally it is pouring out of buckets
Not only Cressier, but the whole of the Central Plateau was hit by violent thunderstorms last week. In the night from Wednesday to Thursday, the canton police received 800 damage reports.
Flooded basements, blocked train stations, bent trees and aquaplaning on the streets – the emergency services had their hands full. Across the country, thunderstorms have shattered huge amounts of vegetables and fruit.
The highest amounts of precipitation fell with 166.7 millimeters in Rüschegg BE and Kiesen near Thun BE with 155.9 millimeters. The statistically normal amount of rain to be expected in June was more than exceeded within a few days.
No relaxation in sight
In principle, violent summer thunderstorms are nothing unusual, says Geraldine Zollinger, meteorologist at Meteonews, to Blick. But: “That we have this enormous thunderstorm potential for several days at a time is extraordinary!”
This is due to a south to south-westerly high-altitude current that transports moist and unstable stratified air from the foothills of the Alps and the Jura to the Swiss Plateau. There it then piles up into destructive supercells because it is still gaining strength thanks to the warm floors.
After a brief relaxation, the weather conditions are practically identical again from Sunday evening. Means: Further storms and damage must be expected. “Where, that can hardly be predicted, since the phenomena involved are very local,” says Zollinger. While some places are literally flooded, it is currently far too dry in Ticino and Engadin.
Our weather is getting more and more extreme
On average, Switzerland is affected by such storms about every five to ten years, most recently in 2016 and 2007. In the future, such events are likely to occur more frequently due to global warming. The weather is becoming more extreme and unpredictable.
“In addition to the general tendency towards decreasing amounts of precipitation in summer, the calculations show that heavy precipitation can be expected more frequently and more intensively,” says climatologist Stephan Bader from Meteo Switzerland. “In other words: In the future summer it will rain less in total, but when it rains it will often be heavy precipitation.”
In this area in particular, the data situation is still extremely thin. A long-term analysis of the periodic frequency of thunderstorms is not available. There are also no reliable figures on the frequency of supercells that were responsible for the damage this week.