Floods in the South-West: red vigilance maintained in 40 and 64, the peak still expected – South West

Two departments of Nouvelle-Aquitaine have been placed in red vigilance since Sunday : the Landes for a risk of flooding, and the Pyrénées-Atlantiques for the risk of floods and rain-floods. At 4 p.m. this Monday, Météo France confirmed this status, while eight departments (Lot-et-Garonne, Gers, Ariège, Hautes-Pyrénées, Haute-Garonne, Ariège, Tarn-et-Garonne and Pyrénées-Orientales) as well as Andorra are on orange alert.

Since midday on Sunday, the Landes and the Pyrénées-Atlantiques have been facing heavy rainfall and flooding. Roads have had to be cut and rail traffic is disrupted. “Damaging overflows” are always to be expected this Monday afternoon and Tuesday on the Gave d’Oloron. “The overflows are especially expected in Béarn, on the side of Oloron-Sainte-Marie and Escos”, specifies Ludovic Delannoy, forecaster at Météo-France.

In Escos, the maximum height of the Gave is expected for Monday at the end of the day, after Vigicrues. It should be between 4.70 m and 5.40 m, a flood lower than that known in December 2021. The Gave de Pau, the Nive, the Adour (in orange vigilance) also overflow their beds. For these sections, the peaks are expected locally overnight or during the day on Tuesday.

115 mm of rain in 24 hours in Iraty

If they are substantial, the precipitation remains less important than last month. In Laruns, between Sunday noon and Monday noon, 100 mm of rain fell. On December 9, the commune of Béarn had recorded nearly 190 mm of accumulations, an absolute record. As a reminder, the standard for the month of January is 180 mm of rain. In Lescun, Météo-France recorded 110 mm of rain in twenty-four hours, 115 mm in Iraty.

At the origin of the phenomenon – as in December – an atmospheric river. “It is a mass of air coming from the tropics, carried towards Europe. Even if it cools down and loses moisture, it still retains its hot and humid character, which causes unusually high precipitation in the region, ”explains Ludovic Delannoy, for whom the duration of the blockage over the Pyrenees is particularly important. notable. In addition to this heavy rainfall, there is an “aggravating factor”: the melting of snow in the massifs. “This Monday, the rain-snow limit is around 1 800/2000 m, adds the forecaster. This further feeds the waterways a little more. “

End of precipitation on Tuesday

The situation should gradually improve by Tuesday noon. Météo-France is forecasting moderate rainfall of around 5 mm per hour this Monday late afternoon on the Béarn terrain. More scattered precipitation is expected over the Basque Coast. A slight lull is expected in the evening, with accumulations between 2 and 5 mm per hour to become weaker and weaker overnight from Monday to Tuesday. The end of the precipitation is expected for Tuesday midday. However, it is difficult to say for the moment when the red vigilance of the Gave d’Oloron can be lifted.