Of
Tuesday September 3 at 5:00 p.m. au
Thursday, September 5 at 12:00
Situation
In an unstable context with a cold drop positioned over the Bay of Biscay, France is at the heart of a conflict of air masses, between the warm air rising on the eastern coast and the cooler air descending via the Channel to the northwest.
During the day on Tuesday, and after a rainy and stormy night in the southwest, thunderstorms are reactivating in the warm air in the east, between Auvergne and the Grand Est with significant rain intensities expected. A risk of gusts exceeding 80 km/h as well as strong electrical activity is established.
Accumulations of more than 40-50 mm are possible in departments on ORANGE alert level, particularly in Franche-Comté.
This Wednesday afternoon, a new stormy deterioration will move from Spanish Catalonia towards Languedoc-Roussillon and the south of the Massif Central.
These new very rainy storms will move up the Mediterranean towards the departments of the PACA region during the night from Wednesday to Thursday, already requiring the Provençal departments to be placed on alert.
Observation
Since late Tuesday afternoon, storms have been breaking out in the Cévennes, Auvergne, Rhône-Alpes and as far as the northeast along the axis placed on alert. These storms remained occasional but tended to become more widespread over the hours. The southern Alps and the Pre-Alps were also affected.
The strongest thunderstorm activity occurs between 10 p.m. and 5 a.m., especially between the Loire and the Grand Est.
Evolution
This Tuesday evening and night from Tuesday to Wednesday
Thunderstorm activity is reaching its peak intensity, between Franche-Comté, Côte-d’Or and then the Lorraine plateaus. In these departments with an ORANGE alert level, thunderstorm activity is expected to be more marked, with accumulations greater than 50 or even 60 mm fairly widespread. Electrical activity is significant under these storms, and the most sustained gusts could exceed 80-90 km/h.
In the second part of the night, the strongest storms will move up to the north of Lorraine and Alsace with still significant rainfall intensities and strong electrical activity. The storms will then move outside our borders, towards Germany during the morning of this Wednesday.
Rain and thunderstorm residues are expected in the northern Alps throughout the morning of Wednesday.
This Wednesday afternoon and evening:
The weather will become very stormy from the afternoon of this Wednesday, with the rise of a disturbance coming from Catalonia. The region should expect violent storms also during the day, as well as the Balearic Islands. These storms, accompanied by a temporary sea wind, will become widespread in Languedoc-Roussillon in the afternoon, heading towards the Cévennes and the lower Rhone valley in the afternoon. It is advisable to take all the usual precautions in the face of this rain storm deterioration.
The maximum intensity of the storms is expected in the evening and during the night all along the Côte d’Azur and then during the night from Wednesday to Thursday, in particular from 11 p.m. to 6 a.m. between Gard, Bouches-du-Rhône and Alpes-Maritimes. A stormy wave is also sweeping Corsica.
In the late evening and night from Wednesday to Thursday, other very rainy storms will rise up from the Mediterranean on the departments of the PACA region. In this configuration, our special press release evolves with the passage to ORANGE alert of the PACA departments and to YELLOW on a part of Languedoc and the lower Rhone valley.
