Eleven departments in the southeast and the Rhone Valley are on orange alert for the day of Thursday due to thunderstorms, strong waves or heavy snowfall, said Météo France in its morning report. The risks of thunderstorms and heavy rainfall concern Bouches-du-Rhône, Vaucluse and Var. The latter department is also concerned by a risk of strong waves and submergence of the coastline, just like the Alpes-Maritimes.
Further north, seven departments are threatened by possible "heavy and early snowfall in the season, in unusual proportions": the Rhone, the Loire, the Saone-et-Loire, the Ardeche, and the Ain , Drôme and Isère, who had already been placed on orange alert Wednesday. In the southern departments, the stormy rains can give "cumulatively, in just a few hours and locally enough, 60 to 100 mm", according to Meteo France.
20 to 30 cm of snow expected on the first heights
"On the coast, more virulent storms can cause, besides a strong electrical activity and intense rains, hail, strong gusts of wind or even swirling phenomena", continues the organization of weather forecasts.
In the Var and the Alpes-Maritimes, "a significant elevation of the sea level is expected" due to strong winds and strong waves. Moreover, "from the middle of the afternoon, the snow will descend to the plain on the departments of the Loire and the middle Rhone Valley".
"The amounts of snow on these sectors can be very important," predicts Météo France. "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 300m the layer of snow can reach 20 to 30 cm, even locally more, "continues Météo France.