Cumbria floods November 2009 — a look back

River breaks its banks in Cumbria

We take a look at how extensive flooding in Cumbria in November 2009 was made easier to deal with because of the warnings from the joint Met Office and Environment Agency Flood Forecasting Centre (FFC).

Heavy rain and gales affected many parts of north-west Britain from 18 to 20 November 2009. The worst-hit area was the Lake District which experienced prolonged heavy rainfall from the evening of Wednesday 18 November through to the early morning on Friday 20 November.The associated high river flows and flooding problems were made worse by already saturated ground. Cumbria had already received close to the whole-month November average rainfall before the heavy rain and gales. The most serious impacts of the flooding were in Cumbria with over 1,300 homes affected, with many more left without power and water. There was severe travel disruption on both roads and railways. Several bridges collapsed and others were closed. Tragically, a police officer died after a bridge collapsed in Workington.

What we did

Throughout the week, during and after the flood, our Public Weather Service Advisors were in constant contact with Emergency Responders about the upcoming heavy rain, helping them to put emergency procedures into place to prepare for the floods. We also kept the Cabinet Office and senior government officials briefed on the situation.

Timeline

Expected rainfall for 20 Nov 2009 Three days before flooding - Monday 16 November

Early identification of disruption risk

  • Met Office early forecast of 100 mm of rain locally
  • National Severe Weather Warning Service (NSWWS) Advisory issued for heavy rain for western areas of the UK (40% risk of disruption)
  • Communication of increased flooding risks from Flood Forecasting Centre

Two days before flooding - Tuesday 17 November

Update of disruption risk

  • Met Office updated early forecast of 120 mm of rain locally
  • National Severe Weather Warning Service (NSWWS) Early Warning of Severe Weather issued for Cumbria and south-west Scotland (60% risk of disruption)
  • Only around ten Early Warnings of Severe Weather are issued per year
  • Mitigation plans developed with Emergency Responders
  • Communication of increased flooding risks from Flood Forecasting Centre

One day before flooding - Wednesday 18 November

Update of disruption risk

  • Met Office forecasts of 250 mm of rain locally
  • After discussion with the Environment Agency, the Scottish Environmental Protection Agency (SEPA) and the Flood Forecasting Centre original warning was upgraded again to an National Severe Weather Warning Service (NSWWS) Early Warning of Extreme Weather issued (80% risk of disruption)
  • Cumbria and Dumfries and Galloway therefore appeared as red on the Met Office website
  • As the highest warning level, only around one or two Early Warning of Extreme Weather are issued per year
  • Emergency Responders - action taken to obtain extra resources
  • Preparation for flooding based on Flood Forecasting Centre outputs

The flooding - Thursday 19 November

  • Met Office forecast that 350 mm of rain was possible in the most exposed locations over high ground
  • In the 24 hours from midnight to midnight on 19 November, Seathwaite in Borrowdale, Cumbria recorded 316 mm of rainfall
  • Emergency Responders put plans into action on the ground

Monitoring the situation - Friday 20 November

  • Heavy rainfall continued through to the early morning on Friday. In total, Seathwaite recorded 378 mm in a 34 hour period from 2000 GMT on 18 November to 0600 GMT on 20 November
  • After a brief respite on Friday, we forecast further rain and strong winds for Saturday
  • This slowed the recovery on the river network in Cumbria and south-west Scotland but did not exacerbate the overall situation in Cumbria and the borders of Scotland

Wettest 24 hours on record

Seathwaite, Cumbria had 316 mm of rain in the 24-hours from midnight to midnight on 19 November - a UK record for any 24 hour period. (The highest ever total for a standard rainfall day (from 0900 GMT to 0900 GMT) of 279mm at Martinstown in Dorset on 18 July 1955 still stands: Seathwaite recorded 253mm from 0900 GMT on 19 November to 0900 GMT on 20 November). Seathwaite also had the wettest ever 2, 3 and 4 consecutive rainfall days in the UK.The worst affected town was Cockermouth where the depth of floodwaters reached 2.5 m. Parts of Scotland were also badly hit with some property flooding and travel disruption in Dumfries and Galloway and the Borders. There was also some flooding in parts of north Wales, causing travel disruption.The extreme weather was caused by an Atlantic weather front becoming almost stationary across Northern Ireland, Cumbria and south-west Scotland. South-westerly winds drew warm, moist air northwards from the Azores region. The mountainous terrain of Cumbria and southwest Scotland intensified the rain.

Weather chart, Nov 2009
Fig.1 Analysis chart valid 0600 UTC 19November 2009
Rainfall Radar image November 2009
Fig.2 Rainfall radar image, November 2009
November rainfall totals in millimetres
Location 0900 17th - 0900 18th (24 hours) 0900 18th - 0900 19th (24 hours) 0900 19th - 0900 20th (24 hours) 0900 18th - 0900 20th (48 hours) 0900 17th - 0900 20th (72 hours)
Seathwaite Farm 60.8 mm 142.6 mm 253.0 mm 395.6 mm 456.4 mm
Honister Pass 73.4 mm 151.8 mm 229.2 mm 381.0 mm 454.4 mm
High Snab Farm 63.0 mm 110.2 mm 228.2 mm 338.4 mm 401.4 mm
Thirlmere, Nook 72.6 mm 103.0 mm 151.2 mm 254.2 mm 326.8 mm
Mickleden, Middle Fell 57.0 mm 106.6 mm 145.6 mm 252.2 mm 309.2 mm
Rydal Hall 49.5 mm 105.5 mm 148.1 mm 253.6 mm 303.1 mm
Grasmere, Tanner Croft 54.0 mm 85.2 mm 155.5 mm 240.7 mm 294.7 mm
Brotherswater 48.2 mm 91.6 mm 153.4 mm 245.0 mm 293.2 mm
Dale Head 51.2 mm 90.8 mm 150.8 mm 241.6 mm 292.8 mm
St Johns Beck 49.4 mm 83.0 mm 133.4 mm 216.4 mm 265.8 mm

The result

People from across the Met Office were closely involved with different agencies throughout the period of severe weather. The unified approach of our Operations Centre forecasters, Public Weather Advisors, the Environment Agency and the FFC received widespread praise. The FFC's joined-up approach was a particular achievement and rainfall estimates provided by Met Office and interpretations of impact provided by the FFC were of the highest standard.

Model performance

Advances in models have helped provide more detailed forecasts. In the days leading up to the heavy rain and flooding, models of higher resolution were used to identify the potential amount of rain and disruption. Starting with a low resolution model (40km) three days before the event, we then used a 12 km model two days before, and eventually we used the highest resolution model available of 1.5 km.

Our world leading 1.5 km model provided impressive demonstrations of its capacity to give realistic rainfall forecasts. It forecast a peak of 269 mm of rain over the Cumbrian Mountains; much closer to the actual rainfall total than the guidance available from other models.

Find out more about Weather forecasting models

The future

Impacts of flooding are devastating and recovery from the flood will take a long time. Our thoughts and sympathy are with all those that have been affected. In coping with the wettest November in the UK in the last 100 years it is encouraging that FFC procedures worked well. For the FFC there are positive signs for the future, with potential for further integrating the science, technology, people and the resulting services.

Last updated: 11 May 2011