Several storm fronts caused heavy hail, heavy rain and storms in parts of Switzerland on Sunday. Floods and damage occurred locally. The federal government had previously warned of great danger.
The first thunderstorm cells reached the country from the west in the afternoon. They first moved across the Lake Geneva region, the Friborg region and parts of the canton of Bern, central Switzerland and further east. Another line of thunderstorms followed in the evening. The Meteonews weather service registered over 36,000 lightning strikes by evening, including around 10,000 in the canton of Zurich.
According to the weather services, up to 31 liters of rain per square meter pelted down in Charmey FR. In Grenchen SO, storm floors roared at up to 118 kilometers per hour. There were also hurricane gusts in the high Alps.
Hailstones five centimeters in size
Hailstones with diameters of up to around five centimeters were reported from the cantons of Bern and Lucerne, as reported by SRF Meteo. The thunderstorms brought a significant cooling. In Geneva, temperatures dropped by more than 5 degrees to around 18 degrees within an hour.
A supercell thunderstorm formed in the Gruyère region. Of these particularly large and severe events, there are usually one or two per summer, said Christophe Salamin, meteorologist at Meteoschweiz, the Keystone-SDA news agency. However, it is rare for this type of storm to move over an inhabited area, as it did on Sunday.
Railway line interrupted in Valais
In the canton of Valais the railway line between Monthey and St-Gingolph was interrupted. The trains were canceled indefinitely due to storm damage.
Initially, nothing was known about further major damage. Locally there were flooded streets, fallen trees, dented cars and broken windows as well as flooded underpasses, as several media reported, citing photos and videos of eyewitnesses.
At the end of the hot spell with temperatures of over 30 degrees, there had been a tropical night in places on Sunday night. The record holder was the Lake Geneva region: the temperature in Vevey VD did not drop below 23.4 degrees at night and in Le Bouveret VS the lowest value was 23.1 degrees, as the private weather service Meteonews announced on Twitter. One speaks of a tropical night when the nighttime temperatures do not drop below 20 degrees.
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