Jersey tornado confirmed as strongest on record

Experts have confirmed that Jersey was hit by a "moderately devastating" tornado during Storm Ciarán.

Analysis suggests it was the most intense tornado recorded in the United Kingdom for nearly 70 years with wind-speeds estimated to be around 160-190mph (260-300km/h).

Disruption to daily life and services continue across Jersey.

Tornadoes in the UK occur more commonly that you might think, with 36 a year on average reported.

That figure is according to Torro (Tornado and Storm Research Organisation), which conducts investigations after suspected tornadoes to keep records and continue research.

Most confirmed tornadoes are however relatively small and cause minor damage.

In Jersey, Torro site investigations concluded that an intense tornado made landfall at St Clement and traversed the island at around midnight on Thursday 2 November.

Severe damage was found along an 8km stretch of the island before it appeared to exit around Fliquet.

After assessing the damage, it has been determined that the tornado was likely to be a "T6 tornado" based on the International Tornado Intensity Scale - from T0 to T10.

T6 tornadoes are classed as "moderately devastating" with damage typically comprising of brick and wooden framed houses wholly demolished, cars thrown over, noticeable de-barking of trees and steel-framed constructions being severely damaged or destroyed.

In a press release, Torro suggests that there have only been a few tornadoes of T6 intensity and greater in the UK, Ireland, Channel Islands and Isle of Man over the last century, and therefore "this is easily the strongest on record for the Channel Islands".

The Jersey tornado was also more powerful than the Birmingham tornado of July 2005 which was rated T5/6 and caused damage estimated at £40 million.

It is also likely the most intense since the Gunnersbury (West London) tornado of December 1954, which was rated T7.

Torro has also assessed damage seen in West Sussex during Storm Ciarán and concluded a T2 tornado went through Sompting and North Lancing on the morning of 4 November.

The clear-up continues in the Channel Islands with some schools yet to be reopened.

While they tend to be small and cause minor damage, tornadoes can occur all year round but are most common in August.

They tend to form when there are severe thunderstorms with frequent lighting, hail and gusty winds. In these storms, rotations can occur in the base of the cumulonimbus cloud which extends down to the ground.

It only becomes a tornado if the spout touches the ground. If it doesn't, it's only a funnel cloud.

The UK has its own "tornado alley" which is in an area between Reading and London.

It's here that a study by the University of Manchester found there was a 6% chance of a tornado each year. The researchers say that this means a tornado is likely once every 17 years.