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Water tornadoes and tornadoes over land in Europe occur more frequently than we think (Photo credit: Getty Images)
These terrifying spinning phenomena on land and water are a lot more common than you might think.
This type of weather phenomenon known as water tornadoes has been making headlines around the world this week after they were believed to be the cause of the sinking of the luxury yacht Bayesian, carrying British tech tycoon Mike Lynch and others, off the coast of Sicily. While these storms may sound like freak events, experts say that both water and land tornadoes are more common in Europe than we might think.
“A waterspout tornado is basically a tornado that occurs over water. A tornado is a column of rotating air that extends from a storm cloud,” says Peter Groenemeyer, director of the European Storm Research Institute, an organization that aims to help Europe prepare for severe storms through scientific research, communication and better forecasting.
Europe experiences about 300 land tornadoes and 500 water tornadoes annually, he said, citing data from the European Severe Weather Database. That's far fewer than the U.S., which experiences about 1,000 tornadoes annually, but it's a threat that needs to be better understood and prepared for, he said, especially as violent tornadoes have caused damage and loss of life in Europe as well. In 2021, violent tornadoes ripped through villages in the Czech Republic, killing several people and injuring more than 150. The state's governor described it as “living hell.”
But experts including Groenemeyer warn that Europe is underestimating the risk of tornadoes and water tornadoes, possibly because national weather services operate independently and don't always share weather data regularly, he says.
“If you think of Europe as one contiguous region, you'll see that tornadoes are not that uncommon,” he says, “but each of these weather services is in a particular county, and of course each small region doesn't see tornadoes that often. That's what we mean by 'underestimated threat'. Each weather service sees tornadoes very rarely, and at that moment they're probably very surprised by this event and think, 'It's hard to prepare for this and give a warning.' It's not considered a sufficient risk.”
For example, an analysis of the Czech disaster concluded that “eyewitness testimony collected after the tornado indicated that many people were unaware of the danger associated with it. Ultimately, most people tried to escape to the safest parts of their homes, but often it was too late.”
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In Europe, around 300 tornadoes occur over land annually (Credit: Getty Images)
Waterspouts may not seem like much of a threat to people on land, but they can be terrifying because they rush towards harbors and coastlines, capsize ships, and do not always stay above water. An analysis of tornadoes and waterspouts recorded in Italy between 2001 and 2016 found that there were 707 waterspouts and 371 tornadoes, with 25% of the waterspouts making landfall and becoming tornadoes.
Water tornadoes typically occur during relatively weak storms, Gronemeyer said. “We call these clear-air tornadoes,” he said. “They occur very frequently in calm conditions near the coastline, where winds from one direction coming from the land and another direction coming from the ocean often interact, so you can have winds coming from different directions close to each other, and where these winds meet, they change direction.”
In the Sicily yacht disaster, the storm appears to have been very strong, but it's unclear whether the plume observed at sea was a water column or a downburst. A downburst is “a huge amount of air that blows out of the storm, hits the ground, and spreads out to create very strong winds,” he explains. On land, experts can look at the shape of the damage path after a storm to assess exactly what the storm was like, but at sea that's not possible. Storms may not leave a record of damage beyond things like broken boats, and that alone isn't enough to paint a clear picture of the incident, he explains.
In recent years, contributions from storm spotters have provided a clearer picture of when and where these phenomena are most likely to occur. An analysis of tornadoes and waterspouts reported in Catalonia on the Iberian Peninsula between 2000 and 2019 found that the Southern European region is a hotspot for tornadoes and waterspouts. With 105 tornadoes and 329 waterspouts reported over an area of 32,000 square kilometers (12,355 square miles), it is one of the densest in the Mediterranean basin.
Images of water tornadoes taken with mobile phones and shared on social media are crucial to better documenting these storms, says Oriol Rodrigues of the University of Barcelona, one of the Catalan study authors. “Large, powerful tornadoes can be detected by operational weather radar, but most weak tornadoes and water tornadoes are too small to be observed by this technology,” he says. “That's why our main source of information is direct witnesses. It's great that people can contribute to improving the detection of this phenomenon and help scientists conduct new research.”
An analysis of 234 waterspouts recorded in the Spanish Balearic Islands between 1989 and 2020 found that most of them occurred in the fall, with the most frequent occurring in September. The researchers analyzed the relationship with sea surface temperature and found that “higher temperatures increase the frequency of waterspouts, especially between 23 °C and 26 °C (73 °F and 79 °F).” The Italian study also found that waterspouts mainly occur in the fall.
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Climate change is causing more intense storms across Europe (Photo: Getty Images)
Understanding how climate change is affecting watertornadoes and tornadoes is another challenge, Gronemeyer said.
Overall, climate change is causing more intense storms in Europe. “There's more energy available for very powerful storms. This has to do with higher evaporation rates as temperatures rise,” says Groenemeyer. Warmer air can hold more water vapor, which condenses in clouds into droplets and ice crystals, releasing heat and creating thunderstorms. “So more water vapor in the air means more powerful storms,” Groenemeyer adds. “This is what's happening in south-central Europe, especially around northern Italy, where warm air from the Mediterranean meets the Alps.”
When it comes to tornadoes and waterspouts, the effects of climate change may be slightly different and aren't yet fully understood, Groenemeyer said. For example, he said, the Mediterranean storm season is getting longer, with more storms occurring earlier in August than the typically stormy months of September and October.
Normally, warm, dry air from the Sahara covers much of the Mediterranean, forming a kind of lid that prevents the air just above the ocean from rising. But “when sea surface temperatures rise, it becomes easier for conditions to arise where moist, hot air from below can break through this lid of air coming from the Sahara,” Gronemeyer says. “So warmer sea surface temperatures can lead to more storms earlier in the season.”
As part of a growing global effort to respond to extreme weather, the European Storm Institute launched a campaign called “TIM” to better understand storms, especially those near mountain ranges. The campaign connects data from meteorological services across Europe and collects additional data with mobile radars, weather balloons, and sensors. This will ultimately help scientists better predict and prepare for these storms, Gronemeyer says.
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