Record-breaking Storm Dennis turns deadly as floodwaters rise across the UK
By
Courtney Travis, AccuWeather senior meteorologist &
Maura Kelly, AccuWeather meteorologist
Published Feb 13, 2020 5:19 PM EDT
A severe flood warning was issued for the River Taff at Pontypridd, Wales, on Feb. 16 in the wake of heavy rain brought by Storm Dennis.
At least two deaths have been attributed to Storm Dennis as it pushed through the British Isles this weekend, while also bringing widespread wind damage and flooding.
The Army has been deployed in the United Kingdom, to help with flood relief for the powerful storm as the region continues to clean up following blizzard conditions and powerful winds over the weekend.
On Saturday, the central pressure in the storm dropped down to 21.17 inches of mercury (920 mb), allowing it to become one of the strongest ever observed over the North Atlantic Ocean. Dennis approached the intensity of the the Braer Storm, which bottomed out at a pressure of 26.96 inches of mercury (913 mb) in 1993.
In Iceland's capital of Reykjavik, a 70-mph wind gust was reported around 8 a.m., local time Friday, while farther west of the city, an 89-mph gust was reported in the town of Keflavik.
Increasing winds across England and Wales were reported on Saturday. Cairngorm Summit, in the mountains of Scotland, reported a wind gust of 150 km/h (93 mph). The Liverpool airport reported wind gusts of 75 km/h (47 mph) on Saturday evening.
Strong winds continued to blow across the United Kingdom on Sunday. Gusts of 130 km/h (80 mph) were common across the region with the highest gust reaching 180 km/h (112 mph) in Bealach Na Ba in the Scottish Highlands.
Dennis caused diverted and canceled flights into and out of the United Kingdom through the storm.
London Heathrow Airport on Saturday evening was reporting delays of around 30 minutes, because of the storm, according to FlightAware. Between Heathrow and Gatwick Airports, over 170 flights were cancelled on Saturday, plus another 150 cancellations and 800 delays on Sunday.
On Sunday, flights that were able to land in London Heathrow battled a strong crosswind. Technical difficulties at the airport added to travel disruptions at the Heathrow airport. These issues were resolved late Sunday.
After Ciara barreled through the same area less than a week ago with gusty winds and heavy rain, the already wet soil and weakened trees helped expand the power cuts in the region over the weekend.
CLICK HERE FOR THE FREE ACCUWEATHER APP
While some football clubs and rugby teams braved the rain and gusty winds, matches where more dangerous conditions were expected were cancelled or postponed on Saturday and Sunday.
Widespread rainfall totals of 50-100 mm (2-4 inches) were reported across the region throughout the weekend. Crai Reservoir in Wales recorded the highest rainfall amount of 157.6 mm (6.20 inches).
Thunderstorms popped up in parts of England and Wales on Sunday night. These storms added to the flooding rainfall and produced hail and lightning.
A major incident has been declared by officials in southern Wales as a dangerous situation unfolds. Rounds of heavy rain on Saturday and Saturday night have have turned streets into rivers and caused landslides in the area.
Rounds of downpours caused rivers to rise across the region along with hundreds of flood warnings and alerts across the U.K., with a record number of flood alerts and warnings in England alone. Emergency services have been working to evacuate residents in southern Wales after River Taff flowed over its banks.
Warnings and alerts were still in effect on Monday, including severe flood warnings in parts of England.
Following the storm, another death has been reported in South Wales, where some of the worst flooding continued on Sunday.
Storm Dennis on the above satellite image is swirling near Iceland on Saturday evening, but sending heavy rain and damaging wind gusts into the British Isles and northern Europe
In addition to the winds and heavy rain, Storm Dennis brought impressive waves.
As the storm began lashing Iceland on Friday, it stirred up terrifying surf, with some swells in the North Atlantic reaching as high as 64 feet over the open ocean. Closer to land, the wave heights topped 40 feet, according to the National Weather Service Ocean Prediction Center (OPC).
The waves caused coastal flooding and erosion ahead of and through the duration of the storm in western parts of Ireland, Northern Ireland and Scotland, and caused a large boat to be tossed around in the wind and waves.
Rough seas from Storm Dennis are believed to be responsible for the storm-related deaths, as of Sunday.
Strong winds and heavy rain spread farther south and east across northern Europe on Sunday. Winds knocked over trees across Germany leading to train and car accidents that left 9 people injured.
Blustery conditions are expected to continue across the United Kingdom and northern Europe into Monday, while the unsettled pattern is forecast to continue throughout this week.
Storm Dennis, as it was officially named earlier last week, exploded into a bomb cyclone on Thursday after its central pressure plummeted 1.38 inches of mercury (46 mb) in 24 hours. The drop was recorded from 29.4 to 28.1 inches of mercury (996 mb to 950 mb).
As Dennis lunged closer to land late last week, an image of the powerhouse storm as shown on the U.S. Global Forecast System, a weather modeling tool, seemed to depict the storm system making an angry face, AccuWeather Meteorologist Jesse Ferrell noticed while studying the forecast.
Ferrell said the storm, which he dubbed "Dennis the Menace," essentially split into two storms. He referred to the phenomenon as "double-barreled low pressure." The two systems congealed back into one massive storm before clipping the northern islands of the U.K.
The U.S. forecast model shows the storm splitting into two parts, which meteorologists call 'double-barreled' low pressure, then coming back together. The purple colors represent lower pressure. (AccuWeather)
(AccuWeather)
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News / Severe Weather
Record-breaking Storm Dennis turns deadly as floodwaters rise across the UK
By Courtney Travis, AccuWeather senior meteorologist & Maura Kelly, AccuWeather meteorologist
Published Feb 13, 2020 5:19 PM EDT
A severe flood warning was issued for the River Taff at Pontypridd, Wales, on Feb. 16 in the wake of heavy rain brought by Storm Dennis.
At least two deaths have been attributed to Storm Dennis as it pushed through the British Isles this weekend, while also bringing widespread wind damage and flooding.
The Army has been deployed in the United Kingdom, to help with flood relief for the powerful storm as the region continues to clean up following blizzard conditions and powerful winds over the weekend.
On Saturday, the central pressure in the storm dropped down to 21.17 inches of mercury (920 mb), allowing it to become one of the strongest ever observed over the North Atlantic Ocean. Dennis approached the intensity of the the Braer Storm, which bottomed out at a pressure of 26.96 inches of mercury (913 mb) in 1993.
In Iceland's capital of Reykjavik, a 70-mph wind gust was reported around 8 a.m., local time Friday, while farther west of the city, an 89-mph gust was reported in the town of Keflavik.
Increasing winds across England and Wales were reported on Saturday. Cairngorm Summit, in the mountains of Scotland, reported a wind gust of 150 km/h (93 mph). The Liverpool airport reported wind gusts of 75 km/h (47 mph) on Saturday evening.
Strong winds continued to blow across the United Kingdom on Sunday. Gusts of 130 km/h (80 mph) were common across the region with the highest gust reaching 180 km/h (112 mph) in Bealach Na Ba in the Scottish Highlands.
Dennis caused diverted and canceled flights into and out of the United Kingdom through the storm.
London Heathrow Airport on Saturday evening was reporting delays of around 30 minutes, because of the storm, according to FlightAware. Between Heathrow and Gatwick Airports, over 170 flights were cancelled on Saturday, plus another 150 cancellations and 800 delays on Sunday.
On Sunday, flights that were able to land in London Heathrow battled a strong crosswind. Technical difficulties at the airport added to travel disruptions at the Heathrow airport. These issues were resolved late Sunday.
After Ciara barreled through the same area less than a week ago with gusty winds and heavy rain, the already wet soil and weakened trees helped expand the power cuts in the region over the weekend.
CLICK HERE FOR THE FREE ACCUWEATHER APP
While some football clubs and rugby teams braved the rain and gusty winds, matches where more dangerous conditions were expected were cancelled or postponed on Saturday and Sunday.
Widespread rainfall totals of 50-100 mm (2-4 inches) were reported across the region throughout the weekend. Crai Reservoir in Wales recorded the highest rainfall amount of 157.6 mm (6.20 inches).
Thunderstorms popped up in parts of England and Wales on Sunday night. These storms added to the flooding rainfall and produced hail and lightning.
A major incident has been declared by officials in southern Wales as a dangerous situation unfolds. Rounds of heavy rain on Saturday and Saturday night have have turned streets into rivers and caused landslides in the area.
Rounds of downpours caused rivers to rise across the region along with hundreds of flood warnings and alerts across the U.K., with a record number of flood alerts and warnings in England alone. Emergency services have been working to evacuate residents in southern Wales after River Taff flowed over its banks.
Warnings and alerts were still in effect on Monday, including severe flood warnings in parts of England.
Following the storm, another death has been reported in South Wales, where some of the worst flooding continued on Sunday.
Related:
Storm Dennis on the above satellite image is swirling near Iceland on Saturday evening, but sending heavy rain and damaging wind gusts into the British Isles and northern Europe
In addition to the winds and heavy rain, Storm Dennis brought impressive waves.
As the storm began lashing Iceland on Friday, it stirred up terrifying surf, with some swells in the North Atlantic reaching as high as 64 feet over the open ocean. Closer to land, the wave heights topped 40 feet, according to the National Weather Service Ocean Prediction Center (OPC).
The waves caused coastal flooding and erosion ahead of and through the duration of the storm in western parts of Ireland, Northern Ireland and Scotland, and caused a large boat to be tossed around in the wind and waves.
Rough seas from Storm Dennis are believed to be responsible for the storm-related deaths, as of Sunday.
Strong winds and heavy rain spread farther south and east across northern Europe on Sunday. Winds knocked over trees across Germany leading to train and car accidents that left 9 people injured.
Blustery conditions are expected to continue across the United Kingdom and northern Europe into Monday, while the unsettled pattern is forecast to continue throughout this week.
Storm Dennis, as it was officially named earlier last week, exploded into a bomb cyclone on Thursday after its central pressure plummeted 1.38 inches of mercury (46 mb) in 24 hours. The drop was recorded from 29.4 to 28.1 inches of mercury (996 mb to 950 mb).
As Dennis lunged closer to land late last week, an image of the powerhouse storm as shown on the U.S. Global Forecast System, a weather modeling tool, seemed to depict the storm system making an angry face, AccuWeather Meteorologist Jesse Ferrell noticed while studying the forecast.
Ferrell said the storm, which he dubbed "Dennis the Menace," essentially split into two storms. He referred to the phenomenon as "double-barreled low pressure." The two systems congealed back into one massive storm before clipping the northern islands of the U.K.
The U.S. forecast model shows the storm splitting into two parts, which meteorologists call 'double-barreled' low pressure, then coming back together. The purple colors represent lower pressure. (AccuWeather)
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
Report a Typo