Storm Dennis was a deep, Atlantic depression that affected the UK on Saturday 15th and Sunday 16th February 2020, one week after Storm Ciara. Although the UK regularly experiences Atlantic depressions, what is unusual about Strom Dennis is that the depression became a weather bomb, due to a rapid fall in air pressure. This is when the pressure drops more than 24 millibars in a 24-hour period, which happened with Storm Dennis.
Storm Dennis brought a month’s worth of rain in 48 hours to flood-hit parts of Wales, early estimates suggested.
Nearly 16cm of rainfall in 48 hours and wind speeds of 91mph were recorded. The highest rainfall occurred in south Wales, where Crai Resr received 157.6mm of rainfall in 48 hours. The highest wind speeds of 91mph were recorded in Aberdaron on the Welsh coast.
The Cause of Storm Dennis
The Impacts of Storm Ciara (Social, Economic and Environmental)
The Environment Agency said more than 480 properties had been flooded after the storm brought torrential rain and strong winds.
John Curtin, the Environment Agency’s head of floods and coastal management, said on Twitter that number was “likely to rise” – but indicated figures were lower than those for Storm Ciara earlier this month.
A major incident was declared after flooding at properties in Lowdham in Nottinghamshire.
Highways England said strong winds had closed part of the M48 Severn Bridge eastbound, while flooding closed part of the M54 and A-roads in Lincolnshire, Herefordshire, Derbyshire, Nottinghamshire and Gloucestershire.
Many rivers reached peak flow leading to increased erosion along river banks. Many rivers tore loose and carried away trees damaging local ecosystems and habitats.
THE A82 was closed at Three Sisters Park near Glencoe, Scotland after Storm Dennis caused a huge landslide. Drivers faced difficulties passing the road after water, snow and rocks crashed down from the ridge of Aonach Eagach.
Landslide at Glencoe
Landslides also occured in Wales. The example below shows a landslide tearing down a mountain in Tylorstown, Rhondda Cynon Taf, south Wales, on Sunday morning.
Strong winds around the coast led to the formation of destructive waves. These had a considerable impact on beaches around the British Isles. The image below shows the beach at Brighton.
He said it had put £2.4bn into defences over a six-year spending period up until next year, and would allocate £4bn for the next six-year period.
In Wales, people were evacuated from their homes in Monmouthshire and Neath with emergency centres set up in Merthyr Tydfil and Aberfan.
Also in Wales, where hundreds of homes and businesses were badly damaged, the Welsh Government prepared to provide extra cash to councils to help the clear-up.
The South Wales Police statement said the force was co-ordinating a “multi-agency response” across the region.
“The emergency services, jointly with local authority planning departments, local health boards, and organisations such as mountain rescue, Natural Resources Wales and utility companies, are working continuously to ensure the safety and welfare of those affected, minimise damage to infrastructure and property, and minimise disruption,” it said.
If you've found the resources on this page useful please consider making a secure donation via PayPal to support the development of the site. The site is self-funded and your support is really appreciated.
Use the images below to explore related GeoTopics.
Extreme Weather in the UK Summer Heatwave 2018
What is the difference between a tornado and a hurricane?
If you've found the resources on this site useful please consider making a secure donation via PayPal to support the development of the site. The site is self-funded and your support is really appreciated.