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Sunday September 8 at 9:00 au
Sunday September 8 at 11:00 p.m.
Situation
For a week now, France has been under the influence of a depression in the Bay of Biscay which is bringing numerous intense rain and thunderstorms to France.
This is the case again this weekend. Indeed, this depression is moving up towards the Channel basin. At the front, it is bringing up air that is still very unstable with strong storms. These storms affect the whole of the south-east of France up to Rhône-Alpes.
At the same time, the depression moving up towards the Channel is causing an episode of heavy rain in Brittany and Normandy.
Observation
This Sunday at 8 a.m.
Heavy rainstorms are coming up from the Mediterranean and are mainly affecting Provence and Languedoc. In the last 24 hours, 136 mm of rain fell in the Cévennes at Collet (48), 125 mm at Lablachère (07) and 100 mm at Saint-Etienne-Ville-Française (48). At the other end of the country, from the northern coast of Brittany to Seine-Maritime, continuous rains of moderate intensity continue. In the last 24 hours, 65 mm of water fell in Thourie (35), 53 mm in Fleins (35), 47 mm in Ernée (53), 38 mm in Coutance (50) and 37 mm in Englesqueville (14).
Evolution
This morning
The rains continue between Brittany and Lower Normandy with strong gusts of 80 km/h on the exposed capes and coasts. In the south-east, thunderstorms are still breaking out locally in the lower Rhone Valley and in the Cévennes. In Provence Côte d’Azur, the showers are increasing rapidly and taking on a stormy character.
This afternoon and evening
A new burst of rain and thunderstorms is rising from the Mediterranean and is rapidly reaching Auvergne-Rhône-Alpes as far as the Jura. These storms can be violent at times between Corsica and Provence Côte d’Azur as far as the Cévennes with a risk of hail. Heavy rain is crossing the Lyon and Saint-Etienne region. At the same time, it continues to rain heavily from Brittany to Lower Normandy with a strong westerly wind along the coast.
Sunday night to Monday night
The strongest storms are gradually being limited to the Alps and Corsica, where hailstorms are possible with winds of nearly 100 km/h on the reliefs of the Isle of Beauty. In Brittany and Normandy, the rainy episode is fading, with sometimes heavy showers accompanied by gusts of 80 km/h taking over from the rain.
On the episode we expect:
Over the whole episode, we expect:
– a risk of hail during the strongest storms
– strong electrical activity and powerful gusts (80 to 100 km/h)
– accumulations of 30 to 50 mm in a short period of time with accumulations of up to 70 mm over the entire episode. Water levels of around 100 mm are possible in the Cotentin and 150 mm in the Cévennes, corresponding to 1 month of precipitation.
– a risk of urban runoff, floods and flooding in low areas.
