As hurricane Erin is travelling from the United States towards Europe, meteorologists are predicting very heavy rainfall and have issued a level 4 (second-highest) alert for certain Swiss regions.
Starting on the evening of Wednesday August 27th, heavy rain will hit much of Switzerland, according to the official weather service MeteoSchweiz.
Ticino and Graubünden will be particularly affected.
Meteorologists are especially concerned about the municipalities of Sumvitg, Lugnez, the Valser Valley, and the Rheinwald region, where precipitation could reach up to 150 litres per square metre between Wednesday and Thursday evening.
A level 4 out of 5 weather alert has been issued for these areas, as heavy rains increase the risk of flooding and mudslides.
MeteoSchweiz warned that this alert could be extended to other regions as well, depending on how the forecast evolves.
Worst-case scenario
The southern Alps face a particular risk, according to MeteoSchweiz.
Intense downpours and thunderstorms could repeatedly hit the same regions for several hours.
If this happens, the same situation as in the summer and autumn of 2024, when heavy damage was recorded in Ticino and Misox, could recur.
The amount of rain expected in eastern Switzerland (in orange). MeteoSchweiz
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Precipitation will be less intense north of the Alps.
In central and eastern Switzerland, the foehn (dry wind) will hold back the rain in these areas.
But as soon as the cold front approaches on Thursday, and as it passes through, areas affected by the foehn will also experience heavy rain.
According to the latest forecasts, the weather will not settle until Saturday.
As early as Sunday, a new cold front, originating from an Atlantic low, will reach the Alps.
However, the amount of rain it will bring is difficult to estimate at this point, MeteoSchweiz said.
