A degradation will cross France from West to East this Friday, September 2. Locally strong thunderstorms are likely to occur. They will be accompanied by intense rains. Météo France has placed three departments on orange alert. It is a common phenomenon for the regions of the south of France but which is no less dangerous. A degradation will affect the departments of the Mediterranean arc this Friday, September 2. Accompanied by strong thunderstorms, the rains can be heavy under the largest cells. Hail and gusts of wind are also expected. As a result, Météo France has placed three departments on orange alert: Gard, Vaucluse and Bouches-du-Rhône. All the rest of the territory is in yellow vigilance. The precise location still unknown According to the explanations of Météo France, it is the presence of cold air at altitude which explains the instability of the next few days. Until Sunday, locally violent thunderstorms will be feared around the Mediterranean. “The general context makes their forecast very difficult in terms of location. Nevertheless, the south of the Massif Central and the Mediterranean (especially between Hérault and Bouches-du-Rhône) seem to be the most exposed regions, in terms of duration and intensity”, detail the administration. What to expect this Friday? This Friday, thunderstorms will form in the Southwest early in the day, according to forecasts from the Arome model of Météo France. The disturbance will quickly shift to the east and should affect Aveyron between 8 a.m. and 9 a.m. Between 10 and 11 a.m., the thunderstorms will strengthen at the end of the morning and should affect Hérault and Gard between 10 a.m. and 12 p.m. Locally strong thunderstorms this Friday around 11 a.m. Run Arome 12z of 01/09/22 – Météo France via Météociel.fr The disturbance should then evacuate towards the Bouches-du-Rhône in the early afternoon. The biggest cells could be passed in the late afternoon. However, thunderstorms may break out locally, as the context is still unstable. Strengthening of thunderstorms in the evening In the departments placed in orange vigilance, “thunderstorms will develop, especially marked a priori in the evening and first part of the night, with intense precipitation: we expect up to 40 to 60 mm, even 70 to 100 mm in a short time, occasionally a little more due to a risk of stationarity”, indicates Météo France which warns of the “risk of runoff and flooding in places”. Hail, gusts under thunderstorms and intense electrical activity are also to be feared. Forecasters point out that violent episodes cannot also be ruled out in neighboring departments. Saturday and Sunday quieter Saturday should be quieter than the day before. Storms could break out between the Gard and the Bouches-du-Rhône in the middle of the morning, according to the latest forecasts from the Arpege model of Météo France. It is in the afternoon that the precipitation could become general and affect the entire Mediterranean basin. On Sunday, the weather should hardly change. Precipitation will be localized but should not be very heavy. The instability of the weekend could even continue until the beginning of the week. Water for the Gard? In total, over the entire episode, the Arpege model models moderate precipitation in the South. It could fall between 60 and 80 mm, especially in the Gard. Locally, these values may be higher, depending directly on the speed of advance of storm cells. Cumulative precipitation Monday at 8 a.m. Run Arpege 12z of 01/09/22 – Météo France via Météociel.fr First forecasts which remain to be confirmed in the next few hours. Indeed, the modeling of storms and particularly the place of their occurrence is very complicated to predict because of the sometimes random nature of these phenomena.