Cévennes episode: more than 400 mm in the Cévennes with a risk of flooding! – Weather-Languedoc

The degradation is already well established this Friday. The feeling can be very different from one point to another in the region. Concrete example today where we were able to have beautiful sunny periods on the Aude, the POs and even on the plains of Gard while it rained on the Cévennes reliefs. This is a completely classic situation during a Cevennes episode. The sea wind strengthens and drains the soft and humid air. The showers then circulate quickly on the coasts and plains to get blocked on the reliefs. This is why rainfall is irregular in the plains and much more durable in the Cévennes. We are entering the peak of activity for this episode tonight and especially tomorrow. Sunday will still be very rainy and improvement is only expected during the day on Monday.

The rains will mainly increase in the Cévennes over the next few hours with sometimes strong intensities. The storminess will remain weak on the whole but thunderclaps could locally accompany this precipitation. Concerning the plains, the eastern sectors of Hérault and Gard will be concerned. In the end, by Saturday evening, the accumulations could reach 30 to 50 mm in the plains, 60 to 80 mm when approaching the Cévennes and more than 300 mm on the Cévennes reliefs. Note that the weather will be dry in the west of the region.

Map: Météociel

If the precipitation may ease slightly on Saturday night, that will not be the end of the episode. Indeed, the rain will persist in the Cévennes and new rainy axes will form on the Gard then the Hérault. On Sunday, the flow could turn more east / south-east. In this configuration, the rains will be weak in the Cévennes but more pronounced in the Hérault which will be the most affected department for this day. The accumulations could be quite substantial in 24 hours, of the order of 20 to 40 mm in general, sometimes 60 to 80 mm in the interior plains. In the night from Sunday to Monday until Monday morning, a last disturbance will sweep the region from west to east with the arrival of the tramontane.

In the end, in the space of 3 days, the accumulations can reach 10 to 40 mm on the coasts of Hérault and Gard, 40 to 70 mm when going inland, 80 to 100 mm when going towards the reliefs, 200 to 300 mm in the Cévennes, locally more than 400 mm. Although spaced out, these accumulations could generate floods in the Cévennes rivers already affected a few weeks ago: the Hérault, the Gardons, the Cèze and the Ardèche. This remains a classic situation but the first overflows are expected (submersible bridges, flood plains, low points) on the watersheds mentioned.

Animation: Tropicaltidbits

As we can see from the animation above, cold air will rush in behind this disturbance. We will pass into a cooler and quite disturbed West / Northwest flow for the next week. We should therefore expect a drop in temperatures with the return of the wind, especially the north wind. The first snowflakes of the season are expected on the reliefs of Lozère. In the plains, if calm periods are possible, disturbances of low intensity could concern us. The feeling will therefore be worthy of a late autumn.