It will shake up in the coming days. While yellow vigilance for wind, floods, storms, rain-flooding is maintained in forty-three French departments this Monday, October 30, meteorologists are worried about the arrival of a new depression. Named Ciarán, it should hit the north-west of France on the night of November 1st to 2nd.
“From Wednesday evening, the wind will strengthen on the Atlantic coast with winds reaching 100 km/h […] Along the seaside, the gusts will be more violent and could approach 120 to 140 km/h with a 20% higher risk on capes, coasts and exposed islands”, Météo-France alerts. And to add: “Thursday morning, the entire north of France as well as the Atlantic coast will be exposed to violent gusts of more than 100 km/h. Along the edge of the Channel, the wind could reach 120 to 140 km/h with a 20% higher risk on the capes and coasts,” warns the Météo-France website.
The weather phenomenon of “jet streams”
Thus, with winds likely to reach 100 km/h in the north-eastern quarter and 150 km/h on the Breton coast, storm Ciarán is akin to a real “metrological bomb”. In any case, this is what meteorologist Anthony Grillon says from his Twitter account, who warns of a “high-risk day of Thursday, November 2”.
At the origin of the storm, the phenomenon of “jet currents” which, by separating the masses of warm and cold air, causes a powerful wind reinforcing the depressions on the ground. “The jet stream plays a crucial role in the formation of depressions and influences their trajectory,” explains Météo-France, which specifies that “depressions often form near or just below the jet stream and are then guided in their movement by this one.”
1999 in memories
When it is particularly strong and passes through a region, the current can also intensify depressions. This was the case in December 1999, when the north and south of France were hit by two violent storms, Lothar and Martin. These then caused a lot of damage, estimated at 13 billion euros. But it was above all the human toll that had left its mark, with 92 dead and 2,000 injured.
If the weather forecasts call for “greater vigilance” on the high risks of violent winds which could be accompanied by heavy precipitation, there is nothing to envisage at the moment the occurrence of a scenario similar to that of 1999. Aftershock of the storm is however expected at the end of the week, echoing Lothar and Martin, which struck a few days apart. And as in 1999, this second storm, expected on Saturday, would have a good chance of affecting the southwest of the country.