During February 2020 the UK was hit by three storms in quick succession, bringing sustained periods of heavy rainfall and widespread flooding across much of England and Wales. Around 4,000 to 5,000 properties were flooded during this event.
Storm Ciara 8 – 9 February
From late Saturday 8 February through to 9 February 2020, the most intense European Windstorm of the season so far, Storm Ciara, brought damaging winds and persistent heavy bands of rain to much of the United Kingdom. The Met Office issued amber and yellow warnings for rain and strong winds, while the Environment Agency issued more than 200 flood warnings across England. Some areas experienced a month and a half’s worth of rainfall within just 24 hours and wind gusts of up to 90 miles per hour were recorded.
Record-breaking rainfall was experienced at multiple locations:
- Honister Pass in Cumbria recorded the highest rainfall totals in the UK (178mm in 24 hours) (Met Office, 2020).
- An unverified reading of 86mm in 12 hours in Huddersfield indicates that the intensity of the rainfall and river levels in the Calder Valley were close to the records set on Boxing Day 2015 (Examiner Live, 2020).
- At Hebden Bridge the Calder reached 3.35m compared to the Boxing Day 2015 level of 3.63m (Environment Agency, 2020).
More than 500 properties were initially estimated to have been flooded, including 260 in Yorkshire, 150 in Greater Manchester, 100 in Lancashire and 40 in Cumbria (BBC, 2020). Yorkshire, particularly the Calder Valley, Lancashire and Cumbria were most significantly impacted by flooding.
Properties, businesses and schools were flooded in Hebden Bridge, Mytholmroyd, Todmorden, Halifax and Sowerby Bridge. Further flooding was experienced in Bingley, Haworth, Masham, Ilkley and Pateley Bridge. The Cumbrian town of Appleby-in-Westmorland was also severely hit. The River Irwell burst its banks at Radcliffe, Greater Manchester, while areas including Blackpool, Whalley, Longton and Rossendale were affected by flooding in Lancashire.
Nearly 539,000 households across the UK experienced loss of power at some point on 9 February and there was widespread disruption to travel including to flights, ferries and trains.
Several days after the event the number of properties estimated to have flooded rose to around 1,400 with significant parts of the UK left at high risk of further flooding with ground saturated and river levels high.
Storm Dennis 15 – 16 February
From late Saturday 15 February through to Sunday 16 February, Storm Dennis followed Storm Ciara and brought persistent and heavy rain to parts of south England and Wales.
The Met Office issued red, amber and yellow rain warnings and yellow wind warnings for Storm Dennis. The Environment Agency stated that the conditions were dangerous to life and there were a record number of flood warnings and alerts (more than 700 combined) for England alone (BBC, 2020).
Rainfall levels were recorded to be between 180–205% of average in Herefordshire, 130-180% of average across South Wales and 140-210% of average across the Calder Valley. The resulting flooding most significantly affected parts of Herefordshire, Shropshire, Worcestershire, Nottinghamshire and the South Wales valleys.
The smaller rivers Taff and Usk were quick to respond with flooding in Pontypridd and Crickhowell, with the larger Severn, Wye, Avon and Trent catchments being affected over the course of the following 10 days bringing flooding to Shrewsbury, Hereford, Worcester, Staffordshire and Nottinghamshire.
Following the strong forecasts for this event, impacts were initially limited by mitigation measures including the 6km of temporary flood barriers deployed by the Environment Agency. Many of these temporary barriers however were overwhelmed by the sustained high flows following Storm Dennis, causing failures at Bewdley and Ironbridge.
The Environment Agency reported around 1,600 properties flooded during this period in England with a further 1,000 properties likely to be affected in Wales.
Storm Jorge 28 – 29 February
Closely following Storm Dennis, Storm Jorge brought further rainfall towards the end of February 2020. Whilst Storm Jorge did not bring the quantity or intensity of rainfall seen over previous weeks, rain did fall on already saturated ground and was enough to keep river levels high. Further flooding occurred along the downstream sections of the River Aire resulting in properties being affected in Snaith and East Cowick. 
Storms Ciara, Dennis and Jorge brought 44% of February’s rainfall and contributed to a new UK rainfall record for February.
(Pictured right) February 2020 rainfall total as % of long-term average. (Source: Met Office)
JBA’s Event Response team has produced a revised flood footprint indicating the extent and depth of the flooding for the areas affected under a 504 insurance hours clause. This footprint has been derived from flood forecasting models and gauged flow information. The footprint has been validated against satellite and aerial imagery, ground photographs and client claims data. The sequence of images below compares ESA Sentinel-1 imagery to JBA’s flood footprint.
(Above) Comparison of JBA’s flood event footprint (top) and ESA Sentinel-1 imagery 17 February 2020 (bottom) for Upton-upon-Severn, Worcestershire. (Source: Sentinel Hub EO Browser)
(Above) Comparison of JBA’s flood event footprint (top) and ESA Sentinel-1 imagery 17 February 2020 (bottom) for Hereford, Herefordshire. (Source: Sentinel Hub EO Browser)
Overview of JBA’s Flood Event Footprint for Storms Ciara, Dennis and Jorge.
If you would like to receive our latest footprint, please speak to our Event Response team. To ensure you receive all future event response and company updates, subscribe to our mailing list below.
You can also read our blog exploring the value of flood forecasting for risk managers, first presented as a breakfast briefing at Lloyd's of London.
References:
BBC. 2020. Storm Ciara: Man dies as tree falls on car in Hampshire. Available at: https://www.bbc.co.uk/news/uk-england-51441770 [Accessed 10 Feb 2020]
Environment Agency. 2020. River level, River Calder at Hebden Bridge. Available at: https://flood-warning-information.service.gov.uk/station/8097 [Accessed 10 Feb 2020]
Examiner Live. 2020. Huddersfield hit by most rainfall ever over 24 hours and 75mph winds as Storm Ciara causes chaos. Available at: https://www.examinerlive.co.uk/news/west-yorkshire-news/huddersfield-hit-most-rainfall-ever-17717474 [Accessed 10 Feb 2020]
Met Office. 2020. Available at: https://twitter.com/metoffice/status/1226587193059270657 [Accessed 10 Feb 2020]
https://www.bbc.co.uk/news/live/uk-england-hereford-worcester-51521935
https://www.gov.uk/government/news/storm-dennis-vigilance-advised-ahead-of-further-severe-weather-this-weekend
