Eleven departments, located between Saône-et-Loire and Var are placed in orange alert by Meteo France this Thursday morning. But the weather risks are different from one department to another.
Ain, Drome and Isere were already in orange alert for the risk of snow and ice. These three departments will be still until Friday 9 am. This Thursday morning, from 10 am, Meteo France places eight other departments of the South-East in orange vigilance: for snow and ice, in the Ardeche, the Loire and the Rhone; on the coast, the Alpes-Maritimes and the Var for a risk of submersion related to the height of the waves; and finally, for the risk of storms and floods, also in the Var, Vaucluse and Bouches-du-Rhône.
Meteo France anticipates that the disturbance will be more active from midday on Thursday, isothermal phenomena will then take place (abrupt lowering of the rain-snow limit). From the middle of the afternoon the snow will appear even in plain in the departments of the Loire and the average valley of the Rhone.
Up to 20 cm of snow
The amounts of snow on these areas can be very important. We can have, throughout the episode, at low altitude, depending on the ground resistance which will be very variable, a layer of a few centimeters to 20cm. On the first heights, from 300 m the layer of snow can reach 20 to 30 cm, or locally more.In Saône-et-Loire, the snow episode will begin in the evening, at night about 5 cm are expected in the south of the department.
On the storm front, a fairly intense disturbance will appear from mid-morning on Thursday in the Bouches-du-Rhone and Vaucluse, and extend to the Var during the afternoon and in the evening, continues Meteo France .
The stormy rains will accumulate, in just a few hours and quite locally, 60 to 100 mm of precipitation. On the episode of about 6 to 8 hours, the expected water layer is of the order of 70 to 120 mm.
Along the coast, more virulent thunderstorms may cause, in addition to strong electrical activity and intense rainfall, hail, strong gusts of wind or even swirling phenomena.
Significant elevation of sea level
Finally, with regard to the so-called "submerged waves" risk, strong waves from the South to the South-West are amplified by the West during the day, from Provence to the Côte d'Azur and Corsica.
In addition, strong southerly winds will intensify temporarily off Provence and the Côte d'Azur, ahead of a stormy zone moving eastwards in the afternoon and the afternoon. evening, aggravating the state of the sea. In connection with these strong winds and these strong waves, a significant elevation of the level of the sea is expected. The combination of these two phenomena is likely to cause submersions on low or vulnerable areas, warns the institute of meteorology.
Snow, storms, risk of floods … Eleven departments placed in orange vigilanceOuest-France.fr