Tornadoes in Europe: an Unknown Threat
300 tornadoes hit Europe each year, causing injuries and destruction. Still, almost nobody knows they exist.
When you think of tornadoes, you think of the United States. The United States, especially the tornado-prone region called tornado-alley is one of the world’s hotspots for tornadic activity. But the truth is that tornadoes can occur almost anywhere on this planet.
What is a Tornado?
A tornado is a cone of air that spins around itself at high speeds. Only when this cone reaches the earth’s surface, it’s deemed a tornado. Tornadoes form at the base of a cumulonimbus cloud during the most violent storms.
Tornadoes and hurricanes are often used as a synonym. In reality, these two phenomena are wildly different. For starters, a hurricane can get a couple of hundred kilometers/miles in diameter. The widest tornado ever recorded was the El Reno tornado in Oklahoma, US. It measured 4.2km (2.6 mi) in diameter. Besides that, wind speeds can get much higher during tornadic events.
The Three Main Storm Types
Before taking a look at the tornadic activity in Europe, it’s essential to know how tornadoes form. As previously stated, tornadoes form at the base of cumulonimbus clouds. But the vast majority of cumulonimbus clouds never generate a tornado.
There are three main types of (thunder)storms: single-cell, multicell, and supercell. These types start off similarly: a cumulus cloud starts to grow into a cumulonimbus cloud. There are two main parameters that determine the eventual type and severity of the storm.
Temperature and Moisture: these two parameters, including some other smaller ones, are generally combined into one: CAPE (Convective Available Potential Energy). As the name suggests, this parameter indicates the amount of potential energy present in the troposphere. If thunderstorms form, they can use this energy. The higher the CAPE values (higher temperature and more moisture), the more violent storms can become.
Wind shear: wind shear describes changes in wind speed and wind direction with altitude. Wind shear is the main factor in determining the storm type.
- A low wind shear results in single-cell, this type of storm has a relatively short lifespan and is considered weak.
- Moderate wind shear transforms single-cell into multicell. This type of storm keeps generating new cells, resulting in a longer lifespan and more severe consequences.
- When high wind shear (and at least moderate levels of CAPE) are present, supercells can occur. They are called “the mother of all storms”. This is the type of storm producing large hail, severe wind gusts, and tornadoes. They can stay alive for multiple hours at a time.
Supercells
Supercells occur mainly during the summer months, due to higher available energy (higher temperature, humidity). Tornado Alley is known for its photogenic supercells, but these storms can produce some nasty side effects.
Supercells can produce a lot of rainfall in a short period of time. Besides that, there is often a hail core present with hail stones of 1in (2.5cm) in diameter. Storms can produce wind gusts up to 60mph (100km/h).
About one in four supercells produce a tornado.
These supercells aren’t exclusively occurring in the United States. Many countries all over the world get to deal with these sometimes violent thunderstorms, including Europe.
Tornadoes in Europe
Europe receives about 300 tornadoes annually (excluding waterspouts). In comparison, about 1,000 hit the United States in an average year. Most of the tornadoes in Europe are considered weak (F0, F1). Stronger tornadoes are less common. The last time an F5 tornado hit Europe was in 1967, in Palluel, France. In the US, there is an F5 tornado every 16 months (on average).
European Regions Without Tornadoes
Tornadoes occur almost anywhere in Europe. The only regions that are free of tornadoes are:
- Iceland and Northern Scandinavia
- The Balkan and Turkey
Many of the southern European (Mediterranean) regions only have a few historical land tornadoes. But the coastal areas of these regions are prone to waterspouts.
Waterspouts are a type of tornado that forms over water. On some occasions, it impacts coastal areas when making “landfall”. Waterspouts can be split up into two groups: fair-weather waterspouts and supercell waterspouts. The latter is identical to a normal land tornado. The former is less dangerous than a tornado, with lower wind speed and no other side effects.
The Tornado Alley of Europe
There are some regions in Europe that seem to have a much higher density of tornadoes than others. The region that has had the most tornado reports (1950–2015) stretches from Southern England over the Benelux to Germany.
This region got the nickname “Tornado Alley of Europe”, but is it really?
England, the Benelux, and Germany are the most densely populated regions in Europe. Research has suggested that higher population density has an impact on the number of reports. The actual tornado density could be different from the perceived. Especially in Eastern and Southern Europe, the actual numbers could be higher.
Besides this region, islands including Malta and Cyprus have had relatively many tornadoes (mostly waterspouts) over the last 65 years.
Timing and Seasonality
Most tornadoes occur in the summer months, the months of May, June, July, and August account for about 70% of all tornadoes. The winter months account for less than 3% of the total each.
July is historically the month with the most tornadoes, with about 25% of all tornadoes occurring in this month. Most of Western, Central, and Eastern Europe reach their maximum amount of tornadoes in July.
Since temperatures reach the highest during midday and in the afternoon, storms often form during those times of the day. Storms can remain active heading into the evening. It isn’t a surprise that most tornadoes occur between 13h and 19h. Waterspouts occur during the day, without a notable peak, they generally form between 7h and 16h. Waterspouts also tend to form later in the year, when water temperatures in the Mediterranean are higher.
Tornado Classification
Tornadoes are classified on the Fujita scale (F0-F5) or the enhanced Fujita scale (EF0-EF5). These scales take damages and wind speed data into account to estimate the severity of the tornado.
When excluding waterspouts, 300 tornadoes hit Europe each year on average. About 70% of all tornadoes are F0 or F1 in strength. This means that wind gusts reach speeds up to 120km/h (75mph) for F0 tornadoes and 180km/h (112mph) for F1 tornadoes.
About 10% of all tornadoes fall into the F2 or F3 category. Reaching wind speeds up to 250km/h (150mph) for F2 and 330km/h (205mph) for F3 categorized tornadoes. This results in severe damage to buildings and the wipeout of complete forests. Less than 1% of tornadoes fall into the F4 category. The remaining 20% is unclassified.
Injuries and Damages
The number of injuries and fatalities due to tornadoes is relatively low in Europe compared to for example the United States. In Europe, about 1.5 per 10 million inhabitants are injured every year due to tornadoes, and in the United States, there are more than 40 injuries (per 10 million) annually. More and more violent tornadoes are the primary cause, but stronger housing in Europe could also play a role.
The cost of damages due to tornadoes has been on the rise in Europe. In the period 2000–2015, yearly damages accounted for €25 million in costs yearly (on average). In the US, this number hovers around $200–500 million in an average year but can reach as high as $3 billion in some years.
Long-Term Trends
The number of reported tornadoes has risen significantly since 1990. In the 20th century, less than 100 tornadoes were reported annually. Since 2000, that number is about 300. The main reason for this trend is improved reporting. In 2006 the ESWD (European Severe Weather Database) started operations. The ESWD collects and validates severe weather reports, including tornadoes.
Since tornadoes have only been reported on a regular base since about 2000, the time period has been too small to make any conclusions regarding tornado activity in Europe. It is too early to determine if climate change has an impact on the number and intensity of tornadoes. Over the past 15 years, there hasn’t been a significant increase or reduction in the number of tornadoes.
Recent Tornadoes in Europe
In 2022, 251 tornadoes and 523 waterspouts hit Europe. Of the 251 tornadoes, 10% were categorized as strong (F2-F3). Tornadoes caused 84 injuries and 6 fatalities in 2022. In recent history, 2022 was the year with the least amount of tornadoes. In 2017, over 500 tornadoes were reported.
Even though the number of tornadoes was relatively low, an exceptionally severe F3 tornado hit France and Belgium. This tornado which originated southwest of Amiens stayed active for over 145km, making it the longest-recorded tornado in Europe. This tornado was part of a severe tornado outbreak with 11 tornadoes formed on the afternoon of 23 October. The fact that such a strong tornado formed this late in the year, made it even more special.
The tornado outbreak of 9 August 2019 sparked a tornado in Amsterdam (The Netherlands) and an F2 tornado in the town of Pétange (Luxembourg), injuring 19 inhabitants.
The event with the most tornadoes during this century is the tornado outbreak of July 2005. Over multiple days, 46 tornadoes were sparked across Western, Central, and East Europe, injuring 63.
In 2021, a severe F4 tornado hit multiple towns in the Southeast of Czechia. Six people lost their lives, and over 200 got injured. Dozens of homes were destroyed. It is probably the tornado with the biggest human toll in recent history.
Conclusion
Even though the number and intensity of tornadoes in Europe don’t seem significant in comparison with the United States, over 300 tornadoes and 500 waterspouts hit the continent annually.
Most regions of Europe are susceptible to tornadoes. Most of them occur in Western and Central Europe. Most waterspouts occur in the Mediterranean area.
The Tornadoes in Europe might be an Underestimated Threat
