UK has more tornadoes per area than any other country, say Manchester University

The UK has more tornadoes per area than any other country in the world, according to new research from Manchester University.

Data for the study came from TORRO, an organisation which collects severe weather reports from the media and over 350 observers in the UK, Ireland and around the world.

From 1980-2012, the country experienced an average of 34 tornadoes per year, with 95% classified as F0 or F1 grade tornadoes – equalling estimated wind speeds of up to 112 mph.

The remainder were classified as F2 with estimated wind speeds of up to 157 mph, with none reaching anywhere near the heights of the devastating F5s with estimated wind speeds of over 300 mph.

Lead author of the paper Kelsey Mulder, of the School of Earth, Atmospheric and Environmental Sciences at The University of Manchester, said: “F2 tornadoes are still quite strong and are perfectly capable of causing damage and injury.

“For example there was the twister that hit Birmingham in 2005 that caused 19 injuries and £40m of damage.

“Because tornadoes are capable of causing such damage it is important that we have some kind of idea where they are most likely to hit.”

Although the peak season for tornadoes is from May to October, they can occur at any time of the year.

Most of those were in England (78%), with the most prone regions the South, South East and West where the threat of a tornado may be as high as 6% in any given year.

Kelsey explained exactly how tornadoes in the UK were formed compared to the USA.

“It seems that most are created along long, narrow storms that form along cold fronts, whereas most tornadoes in the United States are created by isolated storms, which are more similar to the beautiful supercells you see in the movie Twister,” she said.

“Even in the United States, tornadoes formed along cold fronts tend to be weaker than those formed from supercells. That could be one reason why tornadoes in the UK are much weaker.

“But the process for how tornadoes form along cold fronts is not yet very well understood. Understanding why is my current research project.”

The area of the UK most likely to have a tornado lies between London and Reading, with a 6% chance per year.

There is only a 5% chance per year of a tornado occuring from Bristol, north to Birmingham and Manchester, while the South coast of Wales has the lowest possibility with a 3% chance per year.

Tornadoes are impossible to spot on satellite images and weather radar images aren’t always accurate either.

They can show rotation where a tornado doesn’t occur and sometimes tornadoes occur where rotation is not shown on the radar, so the only way we know about them for sure is from eye-witness reports.

Kelsey explained the reasoning for dedicating her life to studying tornadoes from an early age.

“I was inspired to study these beautiful things when I was six years old,” she said.

“My home town of Boulder in Colorado was hit by one. It was my last day of school when the town was hit. It was only a small one that destroyed a few sheds but I was so scared at the time.

“But then later I realised just how amazing the weather is and I decided I wanted to study it.”

Image by Dnaiel Rodriguez via FlickR, with thanks.

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