Property was damaged and people were forced to leave their homes after a “localized tornado” swept through Greater Manchester during Storm Gerrit on Wednesday.
Greater Manchester Police said they received “numerous reports” of the ‘tornado’ at around 11.45pm in Stalybridge, Tameside on Wednesday, declaring it a major incident due to the “severity” of the damage caused and the potential risk to public safety.
No injuries were reported but many residents were forced to leave their homes, and those with significant damage to their properties were urged not to return until they had been given the all-clear by structural engineers.
Chief Superintendent Mark Dexter, of Greater Manchester Police (GMP), said: “This incident has certainly affected many people in the Stalybridge area and many residents were displaced from their properties overnight. advising those displaced not to return to or enter their significantly damaged properties until they have been assessed by structural engineers.
Last night a supercell thunderstorm crossed Greater Manchester causing damage.
We know from our Doppler radar that it had a strong rotational updraft. Although surface data is yet to be confirmed, the presence of these features suggests that a surface tornado is likely 🌪️ pic.twitter.com/XEG1TkKbjN— Met Office (@metoffice) December 28, 2023
The Tornado and Storm Research Organization said a detailed site investigation would be needed before it can be confirmed that the damage was caused by a tornado.
The Met Office said a supercell thunderstorm – which could cause a tornado – had passed over Greater Manchester on Wednesday night with a “strong rotational updraft”. A spokesman said: “The damage reported from the area would be consistent with a small-scale tornado and radar picked up a feature that could be a tornado. The meteorological conditions in the area also support the potential development of a tornado in the area. 30 tornados are reported per year in the UK, although they often occur when they have little or no impact or are very short-lived features.”
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What is a tornado and what causes it?
Tornadoes are vertical funnels of rapidly spinning air. They often come from supercells – large thunderstorms with winds that are already rotating. According to National Geographic, about one storm in a thousand becomes a supercell, and one in five or six spawns a supercell from a tornado.
A tornado forms when warm, moist air collides with cold, dry air. The cold air is pushed more densely over the warm air, usually producing thunderstorms. The warm air rises through the cooler air, causing updrafts.
If the wind speed or direction changes significantly, that updraft begins to rotate, known as a mesocycle. As that mesocycle draws warmer air from the moving thunderstorm, its rotational speed increases and water droplets from its moist air form a funnel cloud that continues to grow and eventually falls down from the cloud to touch the ground – at that point it is classified. like a tornado.
The tornado then moves across the surface and causes significant damage or destruction to objects in its path. The size and intensity of a tornado varies greatly, the Met Office says, with a typical tornado 20-100m wide at the surface, lasting a few minutes and with a track of around a mile (1.6km). Tornado damage is localized; limited by the track of the tornado.
About 30 tornadoes are reported a year in the UK, according to the Met Office, which are usually small and short-lived, but can cause structural damage if they pass over built-up areas.
When was the last tornado in the UK?
They are tracked by the Tornado and Storm Research Organization (TORRO), which ranks them using a scale that measures their intensity based on wind speed, track length, track width and track area.
The most recent tornado in the UK was in Birmingham in July 2005, measuring T6 on the TORRO scale, causing £40m damage – reportedly the costliest if not the strongest tornado. A tornado that hit Gunnersbury in London in 1954 was stronger, measuring T7 on the scale.
According to TORRO, the most severe tornado recorded in the UK was in 1666 when a tornado passed through Lincolnshire, measuring T8-9 with a maximum reported track width of 200m and a track length of 5km.