The correct behavior during tornadoes

Tornadoes occur in many regions of the world every year, including here in Germany. While they can’t be predicted, there are some ways to protect yourself from them. The knowledge platform Earth and Environment has compiled basic behavioral tips.

The formation of a supercell from thunderclouds: supercells have a high destructive power due to strong downbursts, similar to tornadoes. Tornadoes develop from 10-20 % of the supercells. (Photo: imago/ZUMA Press)

Tornadoes cannot be predicted with current methods (Friedrich, 2017). Current weather forecast models work with a resolution of two to three kilometers. Tornadoes, as they also occur regularly in Germany, have however a very small extension of up to some hundred meters, so that they cannot be recognized as small-scale phenomena by the weather radar or weather satellites. Relatively reliable predictions, as with hurricanes – d.h. Days in advance – are excluded for tornadoes. Experts can spot supercells a maximum of 18 hours earlier, but they do not necessarily lead to a tornado and their exact path cannot be predicted (Friedrich, 2017; DWD).

Therefore, people who are outdoors are usually on their own. This concerns the recognition of a tornado, but also the ad hoc correct protective behavior. But how can you recognize a tornado early at all?? One thing is clear: If you see funnel-like, rotating cloud tubes in the sky that have not yet reached the ground, there is a high risk of tornadoes in the following 15 to 60 minutes. But there are also other signs: If so-called supercells or powerful ‘wall clouds’ form, as the Americans call them, these are usually harbingers of the most devastating tornado variants. Mesocyclones form in supercells, they are quasi the engine of rotation (DWD). But tornadoes do not always have this characteristic cloud tube. Sometimes they can only be recognized by the sudden and massive kicking up of dust and earth at ground level. If this happens in combination with noticeable cloud formations, it could be a tornado (DWD). Incidentally, the size and shape of a tornado do not tell you anything about its strength (Edwards, 2020, "Spotting and Chasing/What is a "wedge"? tornado? A "rope" tornado?"). Because tornadoes often extend only a few dozen to a few hundred meters, they can usually be dodged on foot. To do this, it is first necessary to observe the tornado and record its direction of travel. Then affected people can move out of the direction of the train. A safe distance of one kilometer from a tornado is usually sufficient.

How much protection does the car offer?

Many people believe that similar rules of behavior apply to a tornado as to a severe thunderstorm. But there are serious differences. If you are surprised by a tornado, a car offers almost no protection – in contrast to thunderstorms. In a thunderstorm, the vehicle serves as a Faraday cage. In the event of a severe tornado, however, cars can easily be lifted dozens of meters into the air. In the case of smaller tornadoes, a moving car can also be blown off the road.

Under no circumstances should you stop with a car under bridges or underpasses, recommends the U.S. weather authority (National Weather Service, 2014). Severe tornadoes, like those that occur in the U.S., can cause even bridges that appear stable to collapse. Even though these severe tornadoes do not occur in Germany as they do in the U.S., small-scale twisters do occur more often in this country than thought. According to the reinsurer Munich Re, the European Meteorological Service (ESWD) assumes 20 to 60 events per year for Germany (Eichner, 2016); for Europe as a whole, 300 to 400 tornadoes are known with certainty. Due to swirling dust, visibility can be so severely reduced within a short period of time during such a weather event that it is no longer possible to continue driving safely. In this case, as in dense fog or a snowstorm, the vehicle must be slowed down quickly and brought to a stop.

Seek safety indoors or in open fields

To avoid being hit by whirling debris, seek out basements and massive stone buildings whenever possible, and stay away from windows and doors (Friedrich, 2017). If there are no stable escape buildings nearby and it is not possible to avoid the tornado, it helps to lie flat on the ground. It is even better to take refuge in a pit, depression or ditch, American experts recommend (Severe Weather Safety Tips). There you have to hold out until you can be really sure that the tornado has passed. The duration of a tornado is between a few seconds and up to an hour, with most tornadoes lasting about 10 minutes (climate change education wiki). With luck, weaker tornadoes pass overhead, and the likelihood of being hit by whirled-up objects also decreases. Perhaps there is also a canyon nearby that can be visited. These are also relatively safe places.

However, in connection with tornadoes, the danger of heavy rain is not small either. The recommendation to lie down in a pit or ravine thus depends on the circumstances. This can provide some protection from the extreme wind speeds, but – due to the tremendous amount of precipitation – ditches, ravines, depressions or basements suddenly filling with water (a particularly common risk in Germany) are just as dangerous as the high wind speeds.

Tornadoes in the USA

Approximately 1.200 tornadoes are counted each year in the U.S. (NSSL). They can be up to one and a half kilometers wide and cover a distance of over 80 kilometers on the ground. Tornadoes rotate even faster than hurricanes, reaching speeds of more than 320 kilometers (200 miles) per hour. The DWD reports maximum speeds of over 500 kilometers per hour already measured. Tornadoes often accompany hurricanes.

Record of tornadoes in the U.S. from 1950 to 2014. (Photo: NASA Earth Observatory/Joshua Stevens)

Tornadoes in the U.S. move forward at an average of 48 km/h (30 mph). However, the range is considerable: anything is possible, from stationary to speeds of 110 kilometers per hour. 88 percent of all tornadoes are weak. They last only one to ten minutes and reach wind speeds of up to 177 km/h (110 mph). Strong tornadoes account for only one percent of tornadoes, but are responsible for 70 percent of fatalities. They last up to one hour and reach wind speeds of over 267km/h (166mph).

Tornadoes can occur at any time of day or night and can also form at any time of year. They are particularly frequent in the southeastern USA and the Central Plains, between the Arkansas and Platte rivers. Dry-cold air often meets moist-warm air from the Gulf of Mexico here. However, tornadoes have occurred in every U.S. state so far. A misconception is that mountainous areas are safe from tornadoes. The fact is, however, that tornadoes are possible anywhere in the U.S. A tornado near the famous Yellowstone National Park, for example, left behind in 2.600-3.000 meters in height leave a trail of devastation. Even though there is talk of a ‘tornado season’ in the USA, it does not exist de facto. A cluster of tornadoes is observed in late May, early June for the Southern Plains and in June and July for the Northern Plains, but tornadoes are just as possible in the other months (NSSL). There is no "tornado season" in the sense, even if the common term suggests it.

About half of the victims of tornadoes in the USA are people living in mobile homes. The houses are usually not sufficiently firmly anchored in the ground and are therefore particularly at risk. Studies show that people often leave their homes far too late despite warnings.

Increasing the risk of tornadoes?

There are currently no valid studies showing that the number of tornadoes is increasing. Both in the USA and in Europe, the number of tornadoes is stable. Tornadoes are difficult to detect. Therefore, even for scientists, the data sets they can draw on are fraught with uncertainty. It is difficult to determine whether climate change will lead to an increase in tornadoes using current measurement methods. There are indications that the intensity of thunderstorms and storms is also increasing in Germany and Europe. With tornadoes, the black box is still relatively large. However, it is known that tornadoes can occur in very many regions of the world, including here in Germany. Many people in Germany have already sighted and observed tornadoes. Therefore, it is good to be sensitized to this natural hazard, because one thing is certain: tornadoes often come as a surprise, but you do not have to be surprised by them in every situation. If you keep an eye on the sky during thunderstorms, you can avoid a possible tornado and seek shelter in the right place.

And one more rather surprising fact to conclude: Besides the U.S., Argentina and Bangladesh are the countries where this natural phenomenon is most likely to occur.

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