Weather alert: Strong thunderstorms in the northwest in Languedoc

From Friday, June 9 at 8:00 p.m. to Saturday, June 10 at 9:00 a.m.

Situation

After several weeks of stormy weather in the south, a more organized and generalized deterioration is taking place this Friday. The storms reach a maximum intensity this evening and in the first part of the night. Languedoc is the most exposed with the south of the Rhone Valley.
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On Saturday, after an overnight lull, thunderstorm activity will resume near southern landforms, as well as from Normandy to central regions. This press release will then be extended, at least until Saturday evening.

Observation

At 21h, the stormy axis stretched from Normandy to Pays de la Loire to Languedoc-Roussillon. These thunderstorms were strong, accompanied by local hail. The most intense electrical activity was reported between Pyrénées-Orientales and Gard as well as in Touraine and Eure-et-Loir. As the strongest storms passed, there were significant accumulations of water. Between 7 and 8 p.m., more than 20 mm of water fell locally in the Hérault.

At 18 o’clock, the stormy-rainy front was present from the east of Brittany to the west of the Massif Central. Strong cells, possibly hailstones, touched the Haute-Garonne, the Hautes-Pyrénées, the Channel, accompanied by sustained electrical activity. Heat storms ahead of the front developed in Bourgogne-Franche-Comté.
Other storms, formed in the Pyrenees, developed as far as the Toulouse plain, then between the Pyrénées-Orientales, Aude and Hérault. The greatest caution is required in these areas for the evening.

Evolution

This Friday

9 p.m.-12 a.m. : this period will become particularly critical in Languedoc and the lower Rhône valley, with very rainy and not very mobile storms which are likely to cause major flooding. Caution is strongly recommended and travel in these areas not recommended, with hourly accumulations that can reach three weeks to a month of rain under the strongest cells. Elsewhere, thunderstorms will become increasingly rare.

Night from Friday to Saturday
The violent storm cells, very rainy, in Languedoc and Bouches-du-Rhône, will remain in place until around 2 a.m. then a marked improvement will be felt in the second part of the night. Nevertheless, the localized thunderstorm risk persists throughout the night – possibly until early morning – in the lower Rhône valley.

Attention, if a lull occurs in the morning of Saturday, a resumption of stormy activity is expected in the afternoon, near the reliefs and Normandy in the Center, which will earn us an extension of the special press release.

During this degradation, we expect:

– possible layers of water of 20 to 30 mm on average in the departments on yellow alert
– water levels of 50 to more than 80 mm in the departments in orange, up to 100 mm for the lower Rhône valley.
– risks of runoff and flooding, particularly in the departments in orange
– strong gusts above 90 km/h
– risks of vortex phenomena
– a marked risk of hail in the south-west

List of departments concerned