How often does California get tornadoes

Up to 60 dangerous tornadoes per year: Germany is on Europe's Tornado Alley

Tornadoes are raging not only in the USA, but also in Europe - and especially in Germany. Because our home is in the middle of a European "tornado avenue" that extends from southern England via northern and eastern Germany to Poland.

Another strip, in which the often destructive whirlwinds occur, extends in southwest Germany near the Alps. In addition, tornadoes also occur in other parts of the old continent, albeit much less frequently. Meteorologists from the University of Hamburg estimate their number at 500 to 600 per year.

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The infamous Tornado Alley in the American Midwest produces twice as many tornadoes. Many of them leave wide swaths of devastation and kill residents. On average, around 50 people die there every year as a result of the cyclones. In some years, many “killer tornadoes” also form. Then the number of victims increases considerably. In 2020, 24 killer tornadoes killed 76 people. It was the highest death toll since 2011, when 59 of these frenzied storms killed more than 550 people.

Creation of a tornado

In contrast, most of the tornadoes in Germany and Europe are weaker. This is due to the different landscape profiles in both regions. Basically, tornadoes occur when air masses of different humidity or temperature push one another or collide from different directions

First, thunderclouds form, which spiral into the sky due to the Coriolis effect. Inside this cloud spiral, a second, narrower and faster rotating vortex is created, which extends to the ground. This is the real tornado.

Lifespan less than ten minutes

Unlike hurricanes, which last around a week on average (in rare cases up to four weeks), the lifespan of tornadoes is between a few seconds and over an hour, but on average less than ten minutes. But only about two percent inflate into killer tornadoes. These can devastate a strip of land that is only a few hundred meters wide but up to 160 kilometers long.

In the South and Midwest of the USA, the conditions for the formation of the cyclones are particularly favorable. This is where cold polar air and warm, humid air from the Gulf of Mexico meet. They flow over huge areas with almost no elevation in the ground. This favors the development of the notorious super cells, which usually produce very strong tornadoes.

Mountains as locking bars

In Europe, on the other hand, the Alps block the path of moist subtropical air, and the low mountain ranges also act like natural barriers. However, this does not apply to Tornado Alley: From the south of England to Poland, the terrain is relatively flat, so that warm, humid Mediterranean air and hot, dry continental air masses can flow together almost undisturbed.

Accordingly, tornadoes are usually linked to the warm season and the frequency of thunderstorms. Most cyclones in Germany occur in July. The maximum over the North and Baltic Seas is in August and over the Mediterranean Sea in October. However, they also occur occasionally in winter. Great Britain is the country with the most tornadoes per unit area in the world: meteorologists there count around 40 to 50 tornadoes annually, with an accumulation in southern England. However, the majority of storms are weak.

Tornadoes in Germany

This also applies to Germany, where, according to the German Weather Service (DWD), between 30 and 60 tornadoes occur each year, causing damage. On average, however, around ten storms are more destructive. They go hand in hand with considerable devastation and even claim fatalities.

A devastating cyclone in Hamburg in 2006 knocked down three construction cranes and killed two people. Pforzheim in Baden-Württemberg was just as badly hit in July 1968. There were also two deaths there, plus around 200 injuries and damage in the tens of millions. A tornado in 2004 drew an even greater swath of devastation through the towns of Micheln and Trebbichau in Saxony-Anhalt. Eleven people were injured and 275 homes were damaged.

In May 2018 a tornado swept through the Viersen area in North Rhine-Westphalia. Again the result was severe devastation, two people were injured. The DWD assigned the tornado to level 1, which is considered "moderate". But here, too, wind speeds of up to 180 kilometers per hour are possible. The long-standing focus of the Windhosen has been in that region.

Risk of tornadoes increases

Overall, however, the Europeans are lucky with their Tornado Alley: Compared to the North American Tornado Alley, it is tiny, and it is repeatedly crossed by cold fronts, which prevents the formation of tornadoes. On the other hand, the risk of storms increases due to climate change.

According to the Munich reinsurance company, there are more and more extreme weather conditions with storms, heavy rain and hail. In Germany, their number has more than tripled since 1970 from an average of 10 to 35 per year. This also increases the risk that a black hose sinks to the ground from a thunderstorm cell and pulls everything in its way with it.

Also read:

Death zone: There is a risk of suffocation in the eye of the tornado

Drought, storms, heat: How Germany can arm itself against extreme weather

Monster storm or weakening? This is what happens when two hurricanes collide

(Editor's note: This article was first published in 2019)