Tree uprooted by the storm in Saint-Étienne (Loire) on Wednesday August 17, 2022 – photo via Twitter
As expected, the last few hours have been very turbulent in France and particularly in the south-east where torrential storms have generated sometimes significant flooding. Full update on this stormy episode.
An active storm degradation
An area of low pressure present over the northern Atlantic has extended a deep trough to northern Spain, favoring the formation of a low pressure low towards the Bay of Biscay. Ahead of this thalweg, very hot air was rising over Central Europe, overflowing into eastern France, while noticeably cooler ocean air was reaching the west of France, creating a conflict air masses at the origin of a strong instability on the whole of France.
Continental situation for Wednesday August 17, 2022 – via ECMWF
As shown in the map below, more than 79,000 lightning strikes were detected in France and near the country in the space of 48 hours on Tuesday August 16 and Wednesday August 17, 2022. If thunderstorms were widespread in Languedoc on the Côte d’Azur, they were more disorganized on the other regions. However, there was fairly marked stormy activity from the south-west towards Lyonnais via Auvergne and in the north-west quarter, from Brittany to Hauts-de-France, including the Paris region.
Lightning strikes recorded on Tuesday August 16 and Wednesday August 17, 2022 – via lightningmaps.org
Consequently, the rainfall accumulations proved to be particularly heterogeneous during this stormy degradation. The largest were observed along the Gulf of Lion between Hérault and the coast of Bouches-du-Rhône, reaching and locally exceeding 100 mm: 114 mm in Saint-Sauveur-Camprieu in the Gard, 123 mm in Plans in Hérault! The accumulations could locally reach 40 to 70 mm over Auvergne and the west of Rhône-Alpes, the same in certain localities of Normandy or Essonne.
Total precipitation on Tuesday August 16 and Wednesday August 17, 2022 – via infoclimat.fr
Torrential storm in the Paris region on August 16
Almost all of France was exposed to a risk of thunderstorms on Tuesday August 16, 2022 and our forecasts mentioned this risk of thunderstorms in Paris. However, no one could have expected such an active stormy system to circulate in full over the Paris region. As the radar images below show, the storm developed and strengthened rapidly over Essonne before moving up to Paris where it dumped large amounts of rain for more than an hour, especially between 6 p.m. and 7 p.m. this Tuesday, August 16, 2022.
Radar images in Île-de-France on Tuesday August 16, 2022 from 5 p.m. to 7:45 p.m. – via meteociel.fr
The Paris region was indeed the epicenter of this stormy episode! Indeed, it is the station of Paris-Montsouris which received the largest quantities of rain with a total of 47 mm when the storm passed, including 39 mm between 6 p.m. and 7 p.m.! Our station of Saint-Germain-des-Prés measured 30.8 mm and it fell 29.9 mm at Lariboisière. South of Paris, more than 32 mm were measured at Villacoublay and Orly. To the east of the capital, 28 mm was noted in Lagny-sur-Marne.
Cumulative rain in Île-de-France on Tuesday August 16, 2022 – via meteociel.fr
With such amounts of water falling in such a short time, many urban floods have been observed. Paris is not used to receiving more than 40 millimeters of rain in the space of an hour, so many streets found themselves under water, sometimes reaching a few tens of centimeters like on the avenue de New York (right photos below). The water rushed into several metro stations, such as Balard (left photo below). At 8 p.m., the RATP counted 8 stations closed due to flooding.
Floods in the metro and the streets of Paris on the evening of Tuesday August 16, 2022 – via Clement Parrot
In addition to waterspouts, the capital also suffered powerful gusts of wind when the storm arrived. The strongest winds were observed in the south-west of Paris, causing many trees and branches to fall, particularly in the 15th and 16th arrondissements. A gust of 104 km/h was measured by the station located at the top of the Eiffel Tower.
Falling trees after the storm in Paris on Tuesday August 16, 2022 – photo Pierre Desire Bonaventure
Southwestern hailstorms in Rhône-Alpes
At the end of the day on Tuesday August 16, 2022, violent storms broke out in the south-west of France, affecting in particular the Midi-Pyrénées region before shifting towards the Cévennes. They were accompanied by locally significant hailstorms, which caused major damage in the vineyards of northern Gers. As shown in the photo below, some producers have lost a good part of their harvests in the Condom sector.
Damage from the hailstorm on Tuesday August 16, 2022 in La Tenarèze in the Gers – via ArmagnacNews
On Wednesday August 17, 2022, new storms broke out in the regions of the Massif Central. Abundant hailstorms were observed in certain Auvergne localities, such as in the Allier department. In the photo below, large quantities of hail have accumulated in the town of Hyds, coating the landscape!
Large amounts of hail in Hyds in the Allier on Wednesday August 17, 2022 – photo Fanny Nicolas
In the middle of the afternoon, violent storms broke out in the Loire department. They particularly affected the north of the agglomeration of Saint-Étienne. The northern districts of the city suffered gusts of wind reaching 100 km / h, torrential rains and very heavy hailstorms. These covered the streets and obstructed traffic! A total of 37.5 mm of precipitation was recorded at the Saint-Étienne station.
Large quantities of hail in Saint-Étienne in the Loire on Wednesday August 17, 2022 – @BikeGaga sur Twitter
As mentioned above, the storm that hit the agglomeration of Saint-Étienne was also accompanied by violent gusts of wind, having locally exceeded 100 km/h in the north of the city! Numerous falling trees and branches have thus been postponed, forcing the intervention of the emergency services. By shifting to the east of Saint-Étienne, the storm produced an exceptional gust of 131 km/h at Saint-Chamond-l’Horme station!
Tree uprooted by the storm in Saint-Étienne (Loire) on Wednesday August 17, 2022 – photo via Twitter
This violent storm has ended its course in the Lyon region. The Lyon-Bron station measured a gust of wind of 95 km/h and torrential rains that gave 33 mm in the space of just 12 minutes! The floods have multiplied in the city but it is south of Lyon that the biggest floods have been observed. In the streets of Feyzin, torrents of mud flooded dozens of homes. We found up to 61 mm at the Mornant station!
Floods in Feyzin (Rhône) under the torrential storm this Wednesday August 17, 2022 – via Kevin Dorey
Torrential storms and flooding in the Mediterranean
From the evening of Tuesday August 16, 2022, violent storms began in Aude and Tarn. They progressed towards Languedoc during the night of August 16 to 17, reaching a peak of intensity along the coasts. Thus, a particularly virulent storm line hit the south of the Gard department with a gust of 146 km/h measured by the Grau-du-Roi station around 00:30! In the early morning, damage was observed, especially on the beach establishments. Note that this station received 89mm of rain during the day, marked by other strong thunderstorms.
Damage to Grau-du-Roi after the storms on the night of Wednesday August 17, 2022 – photo Midi Libre / Julien Mazurier
During the day of Wednesday August 17, 2022, the Gard department suffered several active rainstorm bursts. These caused flooding in some localities, especially near Saint-Gilles where more than 100 millimeters of precipitation fell. Hailstorms and strong gusts of wind were also observed in the region.
Floods in Saint-Gilles in the Gard on Wednesday August 17, 2022 – photo Renaud Gillard / Weather Languedoc
In general, the Mediterranean regions were exposed to a succession of stormy waves producing hailstorms, violent gusts of wind but also and above all very heavy rainfall. In the Bouches-du-Rhône, Marseille suffered a torrential storm at the very beginning of the morning of Wednesday August 17, 2022, having flooded the Prado district including the Old Port. The same scene repeated itself in the evening with the same floods. The two storms gave about 35 mm each, for a daily total of more than 70 mm!
Floods in the Prado district of Marseille on the evening of Wednesday August 17, 2022 – via Florian Labaye
Located to the east of Marseille, the city of Cassis also suffered the same fate with a torrential storm at the very beginning of the morning, having dumped a cumulative 47 mm of rain between 5 a.m. and 6 a.m.! In the evening, another torrential storm gave 25.6 mm in a short time. During these two storms, a torrent of mud crossed some streets in the city center! Thus, Cassis received 72.6 mm of rain on August 17, while only 89.3 mm fell from January 1 to August 16! This means that 45% of the rains for the year 2022 in Cassis fell on August 17!
Floods in downtown Cassis on the evening of Wednesday August 17, 2022 – captures via La Provence
