what is a Cévennes episode, this phenomenon expected in the south of France?

A “Cévennes” episode will affect the departments of Gard, Lozère and Ardèche from this Monday, October 7. What is this natural phenomenon?

Very heavy rainfall. This Monday, Météo-France placed three departments on orange alert (Gard, Lozère and Ardèche) for risks of rain-flooding. In question, a “Cevennes” episode, expected in the coming hours.

This very particular meteorological phenomenon occurs most often in the Cévennes region, this mountain range forming part of the Massif Central, located between the departments of Lozère, Gard and Hérault. These are generally very violent and highly localized storm episodes. They are most often accompanied by torrential rains, reaching more than 200 mm of precipitation in twenty-four hours. This intense meteorological episode leads to flooding in a large number of cases.

Known to meteorologists, the Cévennes episodes are formed when the hot and humid wind from the Mediterranean rises towards the north and meets the mountain range of the Cévennes. The meeting of warm air and cold air results in the formation of rain-laden clouds which will remain stuck in the massif. So much so that the stormy episode can last several hours, or even several days.

Generally speaking, Cévennes episodes are frequent in autumn and take place more precisely in September, October and November. But Cévennes storms can also occur, but more rarely, in spring, in March and April.