ONE person who saw it described it as "like something out of the Wizard of Oz". The towering vortex of air which ripped roofs off homes and factories was one of at least five tornadoes which hit the UK yesterday.

The twisters struck less than a year after a 100mph tornado in London reduced houses in Kensal Rise to rubble. The previous autumn, two whirlwinds in Birmingham destroyed hundreds of homes, hospitalised 39 people and caused millions of pounds worth of damage.

Yesterday, as firemen picked their way through wreckage for a third year in a row, it was time to ask experts in extreme weather whether Britain is now experiencing an annual "tornado season".

Reports yesterday morning suggested that as many as 11 twisters formed separately as a cold front moved north-east across England. Residents reported hearing "horrendous" noises as violent winds tore down trees, pulled off roofs, knocked off chimney pots and, in one case, overturned a caravan.

The Met Office said a weather system "conducive" to tornadoes travelled across the country, with localised winds gusting up to gale force speeds of 40 to 45mph.

Hayley Stroud, 27, described the twister that hit Farnborough, Hampshire, at about 7.30am as "like something out of The Wizard of Oz". About 20 houses were affected by the tornado which blew through the town's Rother Road, according to a Hampshire Fire Service spokesman.

A tornado struck Nuneaton at about 6.15am. Broken fence panels, shards of tiles and pieces of wood littered both streets as the fire service worked on the roofs of several properties. Another hit Northampton just before 7am, uprooting trees, one of which hit an empty school bus.

Incredibly, despite widespread damage to properties and vehicles across England, there were no immediate reports of injuries.

Dr Terrence Meaden, deputy head of tornado research group Torro, said five reports looked certain to be confirmed as tornadoes - in Farnborough, Luton, Nuneaton, Breaston in Derbyshire and Eye, Cambridgeshire.

Dr Meaden said further research may well confirm another six tornadoes in the Midlands. Torro's 300-strong team of researchers will spend the next few days talking to witnesses and tracking the damage to build up a picture of what happened.

A series of tornadoes forming across the country in this way was "infrequent enough" but not unprecedented, said Dr Meaden. Getting 10 to 12 confirmed tornadoes caused by the same weather system happens about once a year, he said. "We average about 70 tornadoes a year in the UK at the moment, plus another 100 instances of funnel clouds."

The UK actually has the highest frequency of reported tornadoes in the world, once you take land areas into account.

Yesterday's twisters struck in the area where tornadoes are most common - central and southern England. If Britain's had a "tornado alley", this would be it.

Scotland only gets three or four tornado reports per year, "but that's partly because the country is so sparsely populated," said Dr Meaden. We think there are a lot more tornadoes unnoticed."

He said autumn was Britain's peak "tornado season".

The reason for this could be the changing seasons, said Phil Garner of Weatherquest, a forecasting company based at the University of East Anglia. "At this time of year, you still have a lot of warm, humid air left over from the summer, which is the classic set-up for a tornado," he said. "When cool, dry air comes in from the Arctic Circle, these get mixed up and this generates great squalls."

In the past, tornadoes in the UK have tended to cause very little damage because, thanks to our relatively small land mass, by the time a storm has been created it has usually gone to sea. But the nation is becoming increasingly alert to how dangerous these phenomena can be.

"It's nothing uncommon now to hear of a tornado damaging a roof, whereas 20 years ago it was a very rare event indeed," explained Mr Garner.

But is the number of twisters actually increasing? "It's very difficult to say," said Dr Meaden. "Reports are increasing, but I think this is more as a result of digital cameras and camera phones being so widely available. More and more people are reporting extreme weather events."

Could it be climate change increasing our risk of being carved up a by a twister? On this, the experts are divided. "Climate change has the potential to increase tornadoes," said Professor Bill McGuire, director of the Benfield Hazard Research Centre. "Global warming will make our weather more erratic, so I would not be surprised if we see more of these kind of extreme events."

Dr Meaden, however, is not convinced.

"There is no obvious link between climate change and tornadoes," he said.

It is not only climate change making the atmosphere unstable. "Heat islands" being produced by expanding urban centres may well be the catalyst for twisters to arise.

"As cities get bigger, they generate heat which elevates the air temperature above that of the surrounding countryside. That could be the final straw which provokes a tornado," he added.

Tornadoes are becoming easier to predict. The night before the storms, Torro issued a warning they were highly likely. "Our forecasters were certain there was a high risk of tornadoes between 6am and 9am. We just didn't know where exactly in England they would hit. The Met Office doesn't issue tornado warnings as they don't want to make the whole country afraid when very few people will be affected."

In the future that may change as climate models are refined to a level where individual towns and cities may be put on tornado alert.

"That's the real challenge for forecasters," said Mr Garner. The people of Farnborough would firmly agree.