Michael McCarthy: Don't hang the Met Office out to dry


Related Topics

They say in French that to understand everything is to forgive everything, and very few people in Britain are in a forgiving mood right now with the UK Met Office, after its scientists promised us a "barbecue summer" – when we have just had one of the wettest Julys on record.

Since admitting it was wrong, earlier this week, the Met Office has been subject to a torrent of criticism, which reached a peak yesterday with a derisive piece by the commentator Simon Jenkins, who said that as the forecasters were now predicting that August would continue to be wet, it would be a good idea to stock up on sun cream.

The chaps down at Exeter (Met Office HQ) are feeling "very bruised", one said yesterday, and while there is indeed at the moment no public inclination to forgive, perhaps it does no harm to try to understand. What exactly did they say and why did they say it?

When the Chief Meteorologist, Ewen McCallum, stood up a press conference in London's Science Media Centre on 30 April, he said it was "odds-on for a barbecue summer". We know all about the last two words. Let's focus on the first two. The odds he was speaking of were precise: they were 65:35. That was because his computer programmers had run 50 different simulations of the weather over the coming summer, and 65 per cent of these had indicated it would be warmer and drier than average, while 35 per cent had indicated the opposite.

Modern weather prediction involves assembling millions of pieces of data from around the world – wind speed, air temperature, air pressure, humidity – and working out how these phenomena will act on each other, simply according to the laws of physics. To get a perfect forecast you would need an infinite amount of data, but with the few million data points we now have we can get a good picture of the next five or six days.

However, accurately predicting longer than that – to make a seasonal rather than a weekly forecast – is very much harder, as a tiny difference in the data inputted at the beginning of such a program can make, over time, an enormous difference in the outcome. (This is the meaning of the often-quoted "butterfly effect" – the microscopic atmospheric perturbation caused by a butterfly flapping its wings might eventually, in theory, result in a hurricane).

So for seasonal forecasting a large numbers of model runs are carried out, each with slightly different inputs. Mr McCallum was merely reporting the result of this particular "ensemble" of forecasts: a 65 per cent chance of a good summer, a 35 per cent chance of a poor one.

This is known as a "probabilistic" forecast, but the public are not used to it, so this year the Met Office tried to "put some flesh on the bones" of its dry percentages, as a source said

The word "barbecue" was the mistake. We saw the barbecue; we overlooked the 35 per cent chance of rain. But it was there. They said that too. They didn't simply get it wrong, so give them a break. They merely ignited hope with a dream of patios and charcoal aromas, and hope is one of the most dangerous commodities of all.

React Now

Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Refrigeration Engineer

£24000 - £32000 per annum: Recruitment Genius: These refrigeration specialists...

Recruitment Genius: Operations Coordinator - Logistics and Supply Chain

£30000 - £35000 per annum: Recruitment Genius: This is an operational role and...

Recruitment Genius: CNC Sheet Metal Worker / Fabricator

£18000 - £22000 per annum: Recruitment Genius: Working within the workshop of ...

Recruitment Genius: 1st / 2nd Line IT Support Engineer

£20000 - £28000 per annum: Recruitment Genius: This specialist high tech compa...

Day In a Page

Read Next

The strangely parallel lives of Oliver Letwin and Ed Miliband

Matthew Norman
A Cafe Nero coffee store in central London  

Caffè Nero’s craven cowardice over badger culling has made me tear up my loyalty card

Jane Merrick
On your feet! Spending at least two hours a day standing reduces the risk of heart attacks, cancer and diabetes, according to new research

On your feet!

Spending half the day standing 'reduces risk of heart attacks and cancer'
Liverpool close in on Milner signing

Liverpool close in on Milner signing

Reds baulk at Christian Benteke £32.5m release clause
With scores of surgeries closing, what hope is there for the David Cameron's promise of 5,000 more GPs and a 24/7 NHS?

The big NHS question

Why are there so few new GPs when so many want to study medicine?
Big knickers are back: Thongs ain't what they used to be

Thongs ain't what they used to be

Big knickers are back
Thurston Moore interview

Thurston Moore interview

On living in London, Sonic Youth and musical memoirs
In full bloom

In full bloom

Floral print womenswear
From leading man to Elephant Man, Bradley Cooper is terrific

From leading man to Elephant Man

Bradley Cooper is terrific
In this the person to restore our trust in the banks?

In this the person to restore our trust in the banks?

Dame Colette Bowe - interview
When do the creative juices dry up?

When do the creative juices dry up?

David Lodge thinks he knows
The 'Cher moment' happening across fashion just now

Fashion's Cher moment

Ageing beauty will always be more classy than all that booty
Thousands of teenage girls enduring debilitating illnesses after routine school cancer vaccination

Health fears over school cancer jab

Shock new Freedom of Information figures show how thousands of girls have suffered serious symptoms after routine HPV injection
Fifa President Sepp Blatter warns his opponents: 'I forgive everyone, but I don't forget'

'I forgive everyone, but I don't forget'

Fifa president Sepp Blatter issues defiant warning to opponents
Extreme summer temperatures will soon cause deaths of up to 1,700 more Britons a year, says government report

Weather warning

Extreme summer temperatures will soon cause deaths of up to 1,700 more Britons a year, says government report
LSD: Speaking to volunteer users of the drug as trials get underway to see if it cures depression and addiction

High hopes for LSD

Meet the volunteer users helping to see if it cures depression and addiction
German soldier who died fighting for UK in Battle of Waterloo should be removed from museum display and given dignified funeral, say historians

Saving Private Brandt

A Belgian museum's display of the skeleton of a soldier killed at Waterloo prompts calls for him to be given a dignified funeral