Why has it been so wet?

Mon, 23/07/2007

The flooding crisis has deepened with the news that 350,000 people are to lose their water supply.

Tewkesbury in Gloucestershire has come to resemble an island and 43,000 homes in the county are without power.

But those outside flood zones have a more selfish concern at heart - when will summer start for real? And, given all the talk of climate change, is this what summers are going to be like in future, or just a glitch?

He said a broad band of low pressure had been sitting across the UK, pushing the jet stream - a ribbon of fast moving air in the upper atmosphere - further south than usual, keeping high pressure and settled weather away from the UK.

"In a normal summer the jet stream is to the north of the UK. This allows the Azores high to build across the UK and bring settled and more typical summer weather for the UK," said Mr Corbett.

Weather maps: Why this summer has been so wet

The rain has been so intense due to the combination of warm moist air, the position of the jet stream and the fact that the storms have been relatively slow to move away, says Paul Davies, chief forecaster at the Met Office.

"It is not possible to say that any single event is caused by climate change," he says. "What we are able to do is estimate the changes in the risk of extreme events occurring due to climate change.

"There is an expectation of heavier extreme rainfall events in most places as climate warms and the atmosphere becomes moister.

"In the UK, extreme rainfall is likely to increase in winter, but in summer the predictions are unclear. Improved modelling and understanding in the future will help us to reduce this uncertainty for the UK."

But Jim Dale, a risk meteorologist at British Weather Services, says it's down to bad luck, not global warming.

"It's a sexy subject and people like to stick labels on things. Global warming is the latest bandwagon going past so whenever we get a heatwave or floods they blame it on that."

And while people have recalled the severe floods of yesteryear, such as 1912, 1947 and 1953, the 2007 events of June and July are just as bad, he says.

Drying up

So is there a silver lining amid all the doom and gloom?

Holidaymakers flying to parts of Europe on the other side of the jet stream can enjoy higher-than-average temperatures there.

And there is a hint that things may dry up in the UK in August, the Met Office predicts.

Its statistics show that average temperatures, which include day and night, have been above average for every month since March 2006.

This is another story of the summer that has gone virtually unnoticed, says Paul Simons, weather columnist in the Times.

"Despite all the gloom and doom, temperatures are fairly normal for the time of year," he writes.

"In days gone by, a wet summer would invariably be cold, even with snow in July and frost in August."