Flooding — Summer 2007
Torrential downpours in May, June and July 2007 left large swathes of the country under water as the rain was followed by widespread flooding. By accurately forecasting the weather, the Met Office kept people informed on what they could expect.
Unsettled conditions dominated the Bank Holiday in early May, bringing rain and showers to many parts of the country. For the following Bank Holiday there was heavy rain. After a reasonably dry start to June, extremely heavy and prolonged rain fell on to an already soggy UK, leading to serious floods which threatened lives and caused substantial damage to property. Tragically some people died and thousands more had to spend nights in temporary accommodation or were left without power.
Part of the reason for the heavy rain was the jet stream - a band of strong winds in the upper atmosphere that influence how weather systems that bring rain to the UK will develop. As the jet stream was stronger than normal, depressions near the UK were more intense. Some of these depressions pulled in the very warm and moist air to the south of the UK, generating exceptionally heavy and intense rainfall.
What we did
- We played a vital role throughout the summer, providing highly accurate forecasts and warnings ahead of the heavy rains.
- Before and during the floods we worked with and advised emergency planners across the UK including the police and military rescue teams, the Environment Agency, the Scottish Environment Protection Agency and COBR (the Civil contingencies committee which leads responses to national crises).
- We issued early warnings of the severe weather several days ahead to advise the public on the possible impacts.
- As more heavy rain fell on already flood-hit areas, we kept everyone informed as the downpours deposited well over three times the monthly average rainfall for June in some places.
- While it is not easy to forecast extreme weather, the heavy rain was well forecast, with Met Office forecasters predicting the heavy and prolonged rainfall.
- There is no doubt that things would have been much worse without early warnings from the Met Office.
What happened in June
On Monday 25 June prolonged heavy rainfall resulted in many parts of north and east England being flooded.
|17 to 20 June||Localised torrential downpours continued with many Flash warnings issued.|
|21 June||News Release issued to highlight unseasonable weather.|
|22 June||Early Warning issued to public, government and emergency services giving three days' notice of potential disruption.|
|23 June||Further warnings and update to Early Warning issued for E/NE England.|
|24 June||Early Warning updated with highest probabilities for disruption in an arc from Yorkshire and Humberside to the Welsh Borders, with rainfall totals of 'up to 100 mm or so'.|
|25 June||Flash warnings issued for heavy and persistent rain across the high risk areas during the day.|
Days before the actual flooding, the ground around the worst-hit areas became saturated by very heavy rain. Many sites in Yorkshire received at least a month's rainfall in 24 hours.
On Monday 25 June a slow-moving area of low pressure brought a prolonged period of heavy rain to northern and central England. Hitting the already saturated north-east, the water had nowhere else to go and, as a result, led to major flooding.
- Five people died.
- Surface water flooding in Hull.
- Widespread disruption and damage to more than 7,000 houses and 1,300 businesses in Hull.
- River Don burst its banks, flooding Sheffield and Doncaster.
- Flooding in Derbyshire, Lincolnshire and Worcestershire.
- Highest official rainfall total was 111 mm at Fylingdales (N Yorkshire). Amateur networks recorded similar totals in the Hull area.
- There were fears that the dam wall at the Ulley Reservoir near Rotherham would burst.
A heightened alert state was retained during the week 25-30 June, because of the threat of further rain.
What happened in July
The second event caused localised flash flooding across parts of southern England on the morning of 20 July, and later in the day across the Midlands.
|16 July||Medium-range computer forecast suggests a vigorous weather system could move toward the UK and engage with relatively warm air over northern France.Met Office Executive Board briefed about the chances of this event.|
|18 July||Early Warning issued in the morning, central and eastern areas of England at risk of disruption from 60-90 mm of rain.|
|19 July||Risk areas narrowed to south-west Midlands, Gloucestershire and Oxfordshire. Possible rainfall total increased to 75-100 mm.|
|20 July||Flash warnings for southern and central England issued before 9 a.m.|
A slow-moving depression centred over south-east England, drawing warm moist air from the continent across the UK. Heavy and slow moving rainfall moved northwards during the day.
- Widespread disruption to the motorway and rail networks.
- In the following days the River Severn and tributaries in Gloucestershire, Worcestershire, Herefordshire, Shropshire broke banks and flooded surrounding areas.
- River Thames and its tributaries in Wiltshire, Oxfordshire, Berkshire and Surrey flooded.
- Flooding in Telford and Wrekin, Staffordshire, Warwickshire and Birmingham.
- The highest recorded rainfall total was 157.4 mm in 48 hours at Pershore College (Worcestershire).
- In August, Sir Michael Pitt conducted an independent review of the flooding. The review recognised our forecasts and warnings had been timely and accurate and also praised the performance of our Public Weather Service Advisors.
- A key recommendation of the Pitt review, after the floods of summer 2007, was that the Environment Agency and the Met Office should work together, through a joint Flood Forecasting Centre , to improve the capability to forecast, model and warn against flooding.
- Developments in Met Office capability such as 1.5 km resolution models and probabilistic forecasts will help the UK to be more resilient to severe weather.