Very strong thunderstorms in the south on Tuesday morning
From Italy, a particularly violent thunderstorm cell moved across Lake Maggiore and the Magadino plains to the Riviera and the Misox and Calanca valleys. The radar images show an extremely high and wide zone with the greatest intensity of precipitation (yellow). This indicates large hail and was also confirmed with reports of hailstones several centimeters in diameter. In Cadenazzo/TI the thunderstorm raged with a gust of 79 km/h.
Large amounts of rain in a short time
In Bellinzona/TI, 23.8 mm of rain fell within just 10 minutes. This is still a long way from the absolute record value for Switzerland of 41 mm in 10 minutes in Lausanne on June 11, 2018, but already above the critical value for the sewage system (from 18 mm in 10 minutes).
Thunderstorms with severe weather potential
It will probably not have been the last strong thunderstorm today. A so-called high-altitude low is slowly moving eastwards from Italy via Switzerland. More thunderstorms and heavy downpours will be triggered in places. A strong line of thunderstorms is possible again towards evening in Ticino. On the northern slope of the Alps, the rain showers will stretch into the night and sometimes even into Wednesday: Here, too, larger amounts of rain can accumulate locally.