First Posting | Summary
Posting Date: March 1, 2010, 7:00:00 AM
A low pressure system that formed off the coast of Africa, just west of Madeira, late last week developed into a severe extratropical cyclone that swept across a region extending from Spain’s northwest Galicia province, through northwest France, Belgium, and Germany, and finally to southern Denmark.
On Saturday, the storm brought wind gusts of up to 195 km/h to higher elevations in the Pyrenees and France’s Massif Central, and up to 150 km/h in coastal regions of western France, which have been hardest hit. A gust of 160 km/h was recorded near the town of Niort, about 50 km inland from La Rochelle, capital of the Charente-Maritime department. Four departments of France—Vendée, Charente-Maritime, Deux-Sèvres and Vienne—had been placed placed on red alert by Meteo France.
Recorded Gust Wind Speeds at Elevations Lower than 1200 meters. (Source: Meteo France)
Much of the damage in France was the result of the coincidence of the storm’s arrival with high tide. High and violent waves overtopped sea walls, inundating parts of La Rochelle where rescue helicopters were deployed to evacuate people from the roofs of their homes, just visible above water. Unreinforced masonry homes in the coastal town of Chatelaillon, just south of La Rochelle, were damaged or collapsed by storm surge, and boats up and down the coast were unceremoniously deposited onshore. Heavy rainfall overtopped or collapsed dikes along the coast, washing out roads and small bridges.
By Sunday, Paris was experiencing gusts of more than 100 km/h. Several century-old trees on the grounds of Versailles were uprooted and debris, including downed signs, was strewn in city streets. AIR France cancelled about 100 flights from Charles de Gaulle airport because of high winds, and rail traffic across the region was shut down as a result of trees having toppled onto tracks.
At the height of the storm, more than a million households were left without power and some 200,000 homes remain without power today. ErDF, the distribution arm of French energy group EDF, has said that it may take several days before power is fully restored.
In Brussels, scaffolding was strewn across city streets and signage was blown from shop fronts. In Germany, downed trees and billboards damaged automobiles and homes in Dusseldorf and Cologne, where gusts exceeded 125 km/h. As Xynthia progressed across northwest of Germany winds blew tiles off of roofs, brought down light metal structures and the large awnings of petrol stations. An entire roof was ripped from a large apartment building in Mainz. Germany was largely spared the power outages experienced by France, as cables are generally located underground. But there were extensive railway disruptions, autobahns were shut off and several hundred flights were cancelled at Frankfurt airport.
Fifty-five people are reported to have been killed by the storm. In France, at least 47 people are reported to have died, most from drowning; ten are still missing. Three people died in Spain, two by a falling tree and one by the collapse of a masonry wall. One person, a 10-year old boy, was killed by a downed tree in Portugal. At least four have been killed in Germany.
The size and intensity of Xynthia were somewhat unusual for a storm this late in the season. However, while some news reports are making comparisons to the 1999 storms Lothar and Martin, the peak gusts from this storm are lower—and lower even than from winter storm Klaus in 2009. According to Meteo France, the maximum recorded gust from Xynthia for elevations lower than 1200m was 160 km/h along the coast and 120 km/h inland. In 1999, Lothar, brought gusts of almost 200 km/h to coastal areas and up to 160 km/h in the interior at these lower elevations.
At the level of wind speeds observed during Xynthia, significant damage can occur to light metal structures such as warehouses, gas stations and non-engineered agricultural buildings and outbuildings. There is also likely to be significant damage to signage and architectural features in low-rise commercial buildings. There is potentially significant damage to roof coverings (tiles) of homes and apartment buildings—particularly those that have not been well-maintained. Airborne debris can also be a source of damage, particularly to automobiles and non-structural elements.
Well-constructed engineered buildings generally do well during winter storms. Damage to these structures is likely to be restricted to glazing and wall claddings. Heavy rain can damage contents when the roofs or windows of buildings have been breached. Extended outage of electricity and disruption to other lifelines can cause significant BI losses in certain regions. Several ski resorts in the Pyrenees are closed and may remain closed until the end of the season.
The French Federation of Insurance Companies (FFSA) has already issued a statement to the effect that it will expedite compensation for damage to structures caused by wind and wind-driven rain, and damage to automobiles caused by wind. There is somewhat less clarity with respect to flood damage; the FFSA has indicated that payments for flood losses will be made only in areas where a state of disaster is declared. These would be indemnified by the French “CAT NAT” insurance Pool, though insurers will likely bear the administrative costs of handling claims.
The AIR extratropical cyclone team is compiling the available meteorological information for winter storm Xynthia for use in the Extratropical Cyclone Model for Europe. AIR clients will be notified when modeled loss estimates are available on AIR’s ALERT website.
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