Cévennes episode this weekend: 200 to 300 mm in the Cévennes, locally 400 mm in 48 hours! – Weather-Languedoc

A Cevennes episode is planned between this weekend and the beginning of next week. This long disturbed period will also bring its share of rains on the plains of Languedoc, where significant but far from exceptional accumulations are expected. Unfortunately, the departments of Aude and Pyrénées-Orientales (where the drought is still accentuating) will be generally spared. Let’s do the full point below. First of all, let’s take a look at the expected meteorological synoptic.

A vast low pressure system is going from tomorrow Friday and until Monday at least to park over Great Britain, with a very strong dynamism. During the period mentioned, several low-pressure talwegs will be linked one after the other over our Mediterranean regions. The flow at altitude will thus curve to the West / South-West (which is not extremely classic) while on the ground it will be directed and focused towards the Cévennes, in the South-East sector. There will thus be on the one hand strong wind shears and on the other hand a lasting moisture supply to the aforementioned sectors.

As of tomorrow Friday, the weather is deteriorating in the Hérault, a good part of the Gard, the Cévennes and the south of Lozère, where the clouds will remain numerous all day. Rains persist durably in the Cévennes, from the morning until the following night, with generally low / moderate intensities of 2 to 4 mm / h. A reinforcement is planned in the evening, with intensities of 5 to 10 mm / h especially near Aigoual as well as on the Cévennes Gardoises. At the same time, rains will occur over a large eastern half of the Hérault and a small western part of the Gard to the plains. They are intermittent and very weak at the seaside, but become more and more regular as one goes deeper into the land. In itself, a situation that could not be more classic.

The rains persist the following night, especially in the Cévennes, where they are copious. On Saturday, the sea wind will intensify with squalls of 60/70 km / h on the coastal plains. We are expecting an increase in the rains in the Cévennes, with hourly intensities of up to 15 to 20 mm / h, locally 25 mm / h, between Aigoual and the south of Mont-Lozère. The rains are overflowing more and more in the plains, especially in the east of the Hérault and the Gard. They are weak to moderate, but could persist for a long time, bringing a watering saving for nature.

The Aude and the POs are on the fringes, with a densely hazy sky and an active wind. For Sunday, the scenario will have to be specified but small rains could persist especially in the Rhône valley, the Gard and the Cévennes. It would be a gloomy day but with more modest amounts of rain. As for Monday, a new active disturbance is seen in the same areas. Moderate and persistent rains are more and more likely for this day, especially between the east of the Hérault, the Gard and the Cévennes.

Over the whole of this episode, accumulations of 30 to 50 mm are expected in the plain, locally 80 to 100 mm in the hinterland of Gard and eastern Hérault. In the Cévennes, we will often have 200 to 300 mm and locally nearly 400 mm (in about 72 hours) on the exposed slopes of Aigoual and Mont-Lozère. Many floods to be expected, but normally of ordinary intensity. We will have to wait until at least the middle of next week to return to calmer weather.