A tornado is a narrow, violently rotating column of air that extends from a thunderstorm to the ground, the circulation of the strongest tornadoes can reach speeds of over 250 mph. Therefore, tornadoes can be among the most violent phenomena of all atmospheric storms we experience and can cause tremendous destruction that can lead to devastating consequences.
The US has more tornadoes than anywhere else in the world, on average, around 1,200 tornadoes a year. The Great Plains in the centre of the country, on average, seeing most tornadoes, hence the area nick-named ‘Tornado Alley’. Warm and moist air from the Gulf of Mexico, dry air from Deserts of the southwest and cold air off the Rocky Mountains and Canada come together to create the perfect conditions for making severe thunderstorms in the middle of America that become powerful enough to produce so many tornadoes, sometimes destructive tornadoes.
Canada, although larger than the USA in land area, on average sees only a tenth of the number of tornadoes than the US, though is second in the world overall for the number of tornadoes on average a year, seeing around 100 tornadoes a year. Most tornadoes occur over the flat Canadian plains and prairie lands of Manitoba, Saskatchewan, Alberta, and Ontario – where warm moist air moving up over the USA from the Gulf of Mexico collides with cold air coming off the Rockies to the west or arctic to the north.
The UK - Although the USA, on average, sees more severe tornadoes and the most tornadoes of any country in the world, it may be a surprise to know the country that receives the most tornadoes in the world by total area is England.
From the Guinness Book of Records:
Between 1980 and 2012, England experienced 2.2 tornadoes per year per 10,000 square kilometres (3,861 square miles) – which equates to one per every 4,545 square kilometres (1,754 square miles) annually. By comparison, the entire USA (including the non-contiguous states of Alaska and Hawaii) experienced 1.3 tornadoes annually per the same area – or one per 7,693 square kilometres (2,970 square miles).
Interestingly, it appears the United Kingdom sees the most tornadoes per year of any country in Europe, not including Russia, with around 30 tornadoes per year on average. With some ‘top ten’ countries with the most tornadoes in the world on average lists published putting the UK 3rd after USA and Canada for the number of tornadoes per year.
Although rare, there have been a few strong tornadoes that have caused damage in the UK. Most recently, in July 2005 a strong tornado hit the southern suburbs of Birmingham, with estimated wind speeds around the funnel of around 130mph. It injured 19 people, causing £40million of damage, tearing up more than 1,000 trees. While in December 2006, a tornado in Kensal Green, North-West London, wrecked property to the tune of £10million.
One of the longest tracks recorded of a tornado in the UK was one that carved a path 70 miles (110km) long through Buckinghamshire, Bedfordshire and Cambridgeshire on May 21, 1950. The small town in Linsdale, Beds, saw fifty houses lose their roofs, a bakery destroyed, farm outbuildings lifted and dumped 100m away from their foundations.
The largest recorded tornado outbreak in the UK occurred on November 23, 1981. 105 tornadoes developed along a cold front that swept through England and Wales, with numerous counties across England and Wales hit by at least one tornado, while Norfolk was hit by at least 13. Most of the tornadoes were short-lived and weak and fortunately no deaths occurred.
Europe - tornadoes that occur in the UK are generally weak and short-lived compared to tornadoes that may occur less frequently in other European countries which can be more powerful and destructive. An area running between NE France across Germany into Poland is kind of Europe’s ‘tornado alley’ with some strong tornadoes occurring here over the years, particularly in summer. The Mediterranean Sea often see waterspouts in the autumn and early winter, when the sea is still warm but cold air polar moving south over it creates deep convection ideal for them to occur, sometimes these waterspouts making landfall and causing damage.
New Zealand, Japan & Australia - other countries that appear in ‘top ten’ lists of the countries of the most tornadoes in the world are New Zealand, Japan and Australia, taking 4th, 5th and 6th place in top ten lists, despite the small size of New Zealand and Japan compared to Australia. All three of these countries see around 16-20 tornadoes a year on average. For New Zealand, it’s the North Island that sees the majority of tornadoes. Auckland, the largest city on the island, even saw a deadly tornadoes in 2011, that killed one person, along with one in 2012 that killed three people.
India and Bangladesh - appear in the top ten too, although not as frequent for tornadoes as countries above, tornadoes can be deadly. The Monsoon season can often produce tornadic activity, one strong tornado that occurred in Assam in 1963 killed more than 100 people, while in Bangladesh strong tornadoes have caused even more death and devastation, not helped by flimsy construction of homes. In 1964, a tornado in the Khulna Division killed 500, and on April 26, 1989, a deadly tornado which occurred in the Manikganj District, killed more than 1,300 and injured 12,000, making it the single deadliest tornado in the world.
South Africa & Argentina - although towards the bottom of the top ten countries for average yearly tornado counts, those that do occur are sometimes strong enough to be deadly, South Africa and Argentina are not stranger to twisters, seeing between 7-10 a year on average. In Argentina, an EF5 rated tornado, the strongest on the scale, moved through the small town of San Justo on 10 January 1973. At 300 yards wide, it damaged nearly 500 homes and killed 63, injuring 350 others.