The record-setting storm brought hurricane-force winds to coastal buildings along the English Channel
Storm Ciarán (Emir), the third significant named storm of the 2023-2024 European winter storm season, set new meteorological records. The storm raced along the English Channel, traveling through northwestern France and southern England and into the Low Countries. Starting early on Thursday, Nov. 2, severe winds exceeding hurricane strength and intense rainfall damaged property in the area.
Although an intense storm with severe winds and heavy rainfall, CoreLogic® does not expect insured losses across the region to be material.
Extra-tropical cyclone (ETC) windstorms like Ciarán regularly cause heavy property damage in infrastructure-rich areas of Europe. They account for one-third of natural peril events in the European region. Although windstorm activity is on par with floods, due to the prevalent insurance conditions and policy take-out in Europe, they are the costliest insured peril in this region.
About the European Storm Ciarán
On Monday, Oct. 30, the nascent frontal cyclone Ciarán began to move across the Atlantic from North America under the influence of a strong jet stream. As Ciarán approached Europe it underwent explosive cyclogenesis and became a “weather bomb.”
To be classed as a weather bomb, an extratropical cyclone’s central pressure must drop by 24 millibars within 24 hours. In Ciarán’s case, the storm’s central pressure dropped by over ~35 millibars in the final 24-hour approach. At 12:00 a.m. UTC on Wednesday, Nov. 1, Storm Ciarán’s central low, which was located in the mid-Atlantic, had a central pressure below 990 millibars. By 24 hours later, 12:00 a.m. UTC on Thursday, Nov. 2, the storm’s low had reached the vicinity of southwest England and the central pressure had plummeted to below 954 millibars.
Surface measurements from the UK Met Office surface showed Ciarán set a new record for the lowest mean sea level pressure recorded in both England and Wales. In Plymouth, England, the government agency recorded a value of 953.3 millibars. In St. Athan, Wales, it recorded 958.5 millibars. The previous record of 959.7 millibars was set in England in 1916, and the prior record of 962.7 millibars was set in Wales in 2010.
Due to the speed and cyclonic motion of an extra-tropical cyclone, the distribution of winds within the storm (i.e., the so-called wind field) tends to be asymmetric with the highest surface wind speeds typically 50-150 miles south of the center of the storm.
When Ciarán was located over Cornwall, UK, at midnight on Thursday, the strongest gusts occurred along the Atlantic coast of Brittany, France. A record gust of 120 mph was set at Plougonvelin, France, and a gust of 111 mph was reported on the promontory of Pointe du Raz in France.
Ciarán is to some extent reminiscent of The Great Storm of 1987 (nicknamed 87J), in terms of location and intensity. Both storms underwent explosive intensification as they reached the UK. Furthermore, 87J contained a so-called “sting jet,” which is a localized area of very strong gusts.
Model analyses of Ciarán suggest it may have produced a sting jet, but this is yet to be validated. However, an important difference between the two storms, and one which resulted in Ciarán being a less severe windstorm event, is the track that each storm took.
The 87J storm arrived in Europe from an approximately northwesterly direction, tracking past Brittany, before its central low crossed the English Channel and then traveled north across the UK, eventually reaching the North Sea at the northeast coast. This resulted in damaging inland gusts in South England.
By contrast, from 12:00 a.m. UTC to 6:00 a.m. UTC on Thursday, Ciarán’s central low skirted eastwards along the English Channel, before moving overland in Hampshire at around 6:00 a.m. UTC. The storm then traveled for a further six hours in an approximately northeast direction across southeastern England, eventually moving over the North Sea in the vicinity of Suffolk at around midday.
During this 12-hour period, the storm’s maximum wind footprint extended along the English Channel, with overland damaging gusts limited to coastal regions. The strongest impact during this period was along the French coast (e.g., 98 mph and 81 mph at Lannion, Brittany, and Le Toquet, Pas-de-Calais, respectively).
The exposed Channel Islands, which from a UK perspective bore the brunt of the particularly strong winds, experienced a maximum gust of 94 mph in Jersey. Southern England coastal regions were impacted to a lesser degree (75mph and 78mph in England’s Newquay and Langdon Bay, respectively).
From 12:00 p.m. UTC to 3:00 p.m. UTC on Thursday, Ciarán continued to move eastwards across the North Sea — at this point its central pressure was weakening — before starting to track to the north at around 6:00 p.m. UTC. During this period, coastal regions of the Netherlands experienced strong gusts (for example, 70 mph at Hoek Van Holland).
Through the rest of Thursday evening, Ciarán weakened as it tracked north over the North Sea and became quasi-stationary on Friday.
Local Impacts: Mostly Power Loss and Transportation Disruptions
Gusts from Storm Ciarán were strong enough to damage property and infrastructure across southern England, northwestern France, and the Netherlands.
Northwestern France was the most affected area in terms of disruption. According to Enedis, the French power supply and distribution company, 1.2 million homes were without electricity, including 780,000 homes in Brittany and 225,000 homes in Normandy.
The most severe damage in the UK was reported on the Channel Islands of Jersey and Guernsey. As noted above, Jersey sustained the highest reported gusts. The Jersey local government declared the event a “major incident.” Schools closed in anticipation of the danger, and 30 people were evacuated from their homes on the island due to damage. Part of the roof of the local hospital in Jersey destabilized due to the wind.
The storm disrupted transportation and shipping networks in southeastern England and along the English Channel, creating long lines of trucks waiting to cross. The Port of Dover suspended sailing operations early Thursday morning local time; however, some shipping resumed by the afternoon. The winds downed trees and power lines. As of Thursday morning local time, 9,000 properties were without power across southwestern England, according to National Grid. Cornwall was hit hardest, but networks in the Midlands and South Wales remained operational.
Across the region, transportation and shipping networks halted as Storm Ciarán passed. The high winds prompted the Dutch airline KLM to cancel all flights in and out of Amsterdam’s Schiphol International Airport on Thursday.
The record low pressure, the hurricane-force wind speeds and the aforementioned impacted areas brought by Storm Ciarán are reminiscent of The Great Storm of 1987 (nicknamed 87J). During the storm in 1987, gusts exceeding 100 mph downed trees and damaged property and power lines. The severe wind wrecked small boats or blew them away from ports along the channel. Insured claims from 87J reached ~€1.7 billion. The loss potential of an 87J-type event with 2023 building counts and insurance conditions could exceed €7 billion, according to CoreLogic’s Eurowind model.
Storm Ciarán’s impact across Europe is expected to be much less severe. Initial damage reports do not indicate widespread damage on a scale like 87J, and the high volume of significant claims is very unlikely to be repeated with Ciarán.
Fortunately, the European insurance ecosystem today, including underwriting practices and claims management systems, is much more efficient and sophisticated than what was in place 35 years ago. Updated practices and technology will likely mitigate additional expenses accrued during the adjustment process.
Tools like CoreLogic’s Eurowind Model capture and quantify the monetary impact of storms like Ciarán as well as events that are much more severe. The model contains 300,000 years of simulated winter storm activity across northern and western Europe, allowing users to effectively manage their risk.
CoreLogic Hazard HQ Command Central™ will continue to analyze the damage left in the aftermath of Storm Ciarán. Additional information, including loss modeling guidance, may be provided if new data is found.
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