A wave of strong storms will sweep the regions from Burgundy to Hauts-de-France, between the end of this Wednesday afternoon and next night, warns Météo France. The meteorological organization thus places 19 departments on orange vigilance (level 3 out of 4) for storms as well as for “rain-flooding” and the risk of flooding. All those in the Île-de-France region are affected by a risk of violent storms.
The list of affected departments is as follows: Somme, Aisne, Oise, Yonne, Aube, Marne, Paris, Seine-Saint-Denis, Val-de-Marne, Hauts-de-Seine, Val-d’Oise, Seine-et -Marne, Essonne and Yvelines. In addition, the entire north and east of the country as well as part of the Alps, but also the Pyrénées-Orientales and Haute-Corse are on yellow alert (level 2 out of 4) for the same reason.
Five departments are placed on orange alert for “rain-flooding”: Seine-Maritime, Eure, Eure-et-Loir, Orne and Calvados. This last department is also affected by an orange “flood” vigilance.
It is from mid to late afternoon that the most virulent storm cells will form. The orange alert lasts until the middle of the night for all the departments concerned except two: Aube and Yonne.
These storms “are expected to be virulent with high intensities of precipitation, hail and gusts of up to 80 km/h. Electrical activity will also be marked,” notes Météo France. In Normandy, which is on the edge of the area most at risk, “the accumulation of precipitation will be occasionally significant”.
A risk of tornado
Estofex, an association of European meteorologists and academics, sees a little broader. The European storm forecast experiment, according to the full name, or European Storm Forecasting Experience, in French, estimates that the area most at risk goes from eastern Hauts-de-France to the Swiss border. Keraunos, the French observatory for tornadoes and violent storms, places almost the same part of the red country, i.e. level 4 out of 5 according to its classification, a level quite rarely used. This area goes from the southern part of Île-de-France to the northwest of Auvergne-Rhône-Alpes, covering the east of the Centre-Val de Loire region as well as the west of the Bourgogne-Franche region. -County.
The observatory warns that the first storms could be “supercells”. This is the most powerful type. They are likely to generate large hail and tornadoes. Keraunos estimates that hailstones of 2 cm or 3 cm could fall in the red area; the risk of violent hail, with a size greater than 5 cm, is “fairly low”, with a probability of between 5% and 15%.
Likewise, the area in red is at risk of tornadoes. It is estimated between 15% and 30%, including throughout Île-de-France. Several tornadoes have formed in recent weeks in France. The one that caused the most damage took place on April 8. It affected the town of Lestrem, in Pas-de-Calais. The risk of such a phenomenon forming in this area had been estimated at between 15% and 30%.
This animation, provided by Météociel, allows you to follow the progression of lightning strikes over the last five hours.
These storms are the result of a conflict of air masses with warm air in the north of the country and cooler air in the southern part. This animation allows you to visualize the situation.
The first fairly strong storms have already occurred on Tuesday. The Marne department was particularly concerned.
Over the next few days, storms should be almost absent. They could return to the South from the end of the weekend.
