Saharan dust and “foehn of the decade” in Switzerland
Published: Saturday, Mar 30th 2024, 18:40
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Dust from the Sahara and a foehn storm caused problems in Switzerland on Saturday. An estimated 180,000 tons of Saharan dust over the country led to poor air quality and cloudy skies, while strong foehn gusts caused isolated damage.
According to meteorologist Jörg Kachelmann, Friday's Föhn storm was the "Föhn of the decade", as he wrote in an online article in the Tamedia newspapers on Saturday. There were winds of 200 km/h on the Lauberhorn BE, gusts of 198 km/h on the Klingenstock SZ and gusts of 191 km/h on the Gütsch ob Andermatt UR. According to Kachelmann, the Swiss Föhn made it as far as Germany.
According to Kachelmann, the extreme event was made possible by a large difference in air pressure between north and south. The high temperatures outside the foehn also contributed to this, "so that no heavy block of cold air had to be cleared away".
Broken ship and temperature records
Strong winds damaged the historic steamboat "Simplon" on Lake Geneva, as the CGN shipping company announced at a press conference. It was towed to the Ouchy shipyard in Lausanne VD. In particular, the "Belle Epoque" suffered a "major water ingress in the stern" and a smaller one in the engine room. Part of the hull and the floor were also torn apart.
The weather had serious consequences for a 60-year-old woman at the Jakobsbad campsite in Appenzell Innerrhoden on Friday: The canopy of a caravan, which had been torn from its anchoring by the storm, fell on her. The woman suffered moderate injuries, according to the cantonal police. She was taken to hospital by Rega.
In addition to the strong wind, the foehn also brought mild temperatures. According to SRF Meteo, the highest temperatures in the Föhn valleys on Friday were just under 22 degrees. In La Brévine NE, the average daily temperature on Friday was 12.7 degrees Celsius, the highest for the month of March since measurements began, according to MeteoSwiss on X. In Château-d'Oex VD and Aigle VD, the average daily temperatures reached the second highest March values at 11.7 and 16.3 degrees respectively.
Extraordinary amount of Sahara dust
The 180,000 tons of sand from the desert calculated by SRF Meteo is more than twice as much as in previous episodes of this kind, as meteorologist Roman Brogli said on the radio. According to the meteorologist's calculations, this could fill around 10,000 law cars. Lined up end to end, they could cause a traffic jam of around 100 kilometers.
When Saharan dust is in the air, it reflects and scatters some of the sunlight. The sky turns yellowish and the sunrises and sunsets are more spectacular. If it settles on snow, it can slow down skiing, among other things.
The dust also leads to an increased concentration of particulate matter in the air. In Davos, it exceeded the scale for measuring particulate matter on Friday, wrote MeteoSwiss on X.
The short-lived Saharan dust is likely to have a negligible impact on the health of the vast majority of people. Natural particulate matter makes up around one percent of the other total particulate matter concentration.
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