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Last Updated: Thursday, 13 October 2005, 16:35 GMT 17:35 UK
Is Brum Britain's tornado alley?
Simon Keeling
BBC weather expert

Damage caused by tornado
October's tornado caused road closures due to rubble
One tornado may be considered a fluke, but another one, within a mile of the previous event and within three months?

This is starting to become a habit!

People in Moseley could be forgiven for thinking that they are living in the UK's very own tornado alley.

Last night's event certainly was nowhere near as severe as the wind that struck on 28th July (which occurred less than a mile away), but it was strong enough to destroy a house roof.

So why should Birmingham be so prone to tornadoes and will they happen again?

It seems the answer lies in the topography of the city.

Explosive results

Birmingham sits on a high plateau, surrounded by lower lying land, notably Worcester and Evesham to the south. Combine this with the physics of the weather and the result can be explosive.

The weather relies on the combination of warm and cold air to form clouds and rain.

Air rises then cools, and so long as the right conditions exist clouds and rain may form. It's the rising of the air which can cause heavy rain storms and tornadoes to form.

With the wind from the south, as was the case last night, air is forced northwards.

As it reaches the Birmingham plateau it can either go around the plateau, or be forced upwards, which is what happened last night.

As a result, large storms clouds formed over the city trapping a vast amount of energy within them. This was released in the form of a tornado; rated about at T2 on the TORRO Tornado Scale.

As for a repetition, the UK is reported to receive more tornadoes per square mile than the USA but most are small events, rarely making the headlines.

For such a small area to see two tornadoes within a few months is very unusual, but this is probably more bad luck than a portent of worse things to come.




SEE ALSO
Clean up follows second tornado
13 Oct 05 |  West Midlands
Second tornado strikes Birmingham
12 Oct 05 |  West Midlands
Tornado is 'worst for 25 years'
29 Jul 05 |  West Midlands
Tornado hits Birmingham
29 Jul 05 |  West Midlands

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