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WATCH: ‘Fog avalanche’ rolls over mountain ridge in Swiss Jura

A new video taken by cross-country skiers shows beautiful fog waves cresting a ridge in the Jura mountains of western Switzerland.

WATCH: 'Fog avalanche' rolls over mountain ridge in Swiss Jura
The Swiss Jura is known for its fog waves.

Tourism authorities in the Jura & Three-Lakes region posted the video online on Monday and it has now been seen thousands of times.

Fog waves are something of a meteorological speciality in the Jura range of Switzerland with the Belchenflue mountain on the borders of the cantons of Basel-Landschaft and Soluthurn offering ideal conditions, according to Swiss daily NZZ.

A combination of geographic and weather conditions is required for fog avalanches to form.

A long, flat ridge is required. The windward side of the ridge needs to have a long steep slope – ideally a cliff – fronted by several kilometres of level country.

On the other side of the ridge, which is sheltered from the wind, the slope needs to be less steep so that the fog can slowly drift downwards.

At the same time, to get conditions like those seen in the Jura on the weekend, you need an upper fog line at the same altitude as – or just above – the ridge line.

A high-pressure area is also needed to ensure stable atmospheric conditions. In addition, the wind must also be blowing down on the ridge line as close as possible to vertical so that fog can be pushed along. Otherwise, it dissipates immediately.

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Why are there so many weather-related disasters in Switzerland this summer?

From mudslides to flooded hiking trails, several Swiss regions have suffered serious weather-related damage during this year’s summer season.

Why are there so many weather-related disasters in Switzerland this summer?

In the past weeks, frequent spells of extreme weather claimed lives and caused considerable material damage in several regions of the country.

Among them:

In June, parts of Switzerland, including the canton of Graubünden and the resort of Zermatt in Valais, were hit by huge floods, which claimed the lives of three people and left buildings and roads destroyed.

They were triggered by a violent thunderstorm that unleashed the rivers, causing a rock and mud avalanche in the municipality of Misox.

Additionally, landslide of mud and rubble destroyed a part of the north-south axis of the A13 motorway.

Areas of Valais and Ticino were also among those badly damaged by storms, with three people dead and five missing in the latter canton; the upper Val Maggia remained cut off from the rest of the country and without water and electricity for days.

And just this week, two people were injured in a massive storm in Brienz (canton Bern) and 70 others had to be evacuated from their homes, after the Milibach river overflowed after heavy rains, carrying stones, boulders and wood, which caused a water collector above the village to flow uncontrollably.

Buildings, parked vehicles, roads and public transport infrastructure were damaged.

Also, more than 620 trails –1,300 km in total – had to be closed to hikers due to heavy rains and flooding that hit some regions of the country at the end of June. 

READ ALSO: Hikers in Switzerland warned as hundreds of trails close

Why has this been happening?

“The summer of 2024 has been marked by particularly bad weather,” said meteorologist Felix Blumer. “There is one or two damaging thunderstorms every summer, but this year, there have been lot of them.”

There is a scientific explanation for this phenomenon: according to Blumer, most of the summer so far, the weather in Switzerland has been dominated by low pressure areas.

“It is precisely the low pressure situations that are important, with the summer solar radiation, the ground heats up very strongly. The warm, light air can rise, cool down, condense – resulting in showers and thunderstorms.”

In a simple(r) language, low pressure gives way to warm air and rainstorms, which explains the high number of strong and destructive thunderstorms.

Is the weather this summer really more ‘extreme’ than in the past?

According to Thomas Schlegel from Switzerland’s official weather service MeteoSwiss, “due to the extreme events that have occurred so far, 2024 will certainly go down in history as a year with a lot of bad weather and damage.”

He also cited “exceptional” lightning activity during the thunderstorms: over 70,000 lightning strikes were recorded — more than during a typical summer.

In fact, two people who were working in a field in Fribourg during one such lightning episode in July, were struck and injured, along with a police officer and a REGA pilot who came to their rescue. 

What’s ahead, weather-wise?

MeteoSwiss’ eight-day weather forecast predicts more rain and thunderstorms, ranging in severity, in various Swiss regions. 

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