Weather alert: heavy rainfall and high risk of flooding in the southwest – La Chaîne Météo

From Saturday January 8 at 10 p.m. to Tuesday January 11 at 9 a.m.

Situation

Under the influence of a vast low pressure system over the north Atlantic, the weather is very agitated and disturbed over France until Monday. A very dynamic west to north-west regime causes inclement weather.

Thus, from Sunday to Tuesday morning, a disturbance is blocked near the Pyrenees, bringing a remarkably durable episode of rainfall of moderate to strong intensity during which we expect 50 to 100 mm of water, and locally 200 to 250 mm, which corresponds to between 1 and 2 months of rain.

In the mountains, we expect 20 to 50 cm of snow around 1500 meters and 1 to 2 meters above 2300 meters. These bad weather can lead to very high risks of floods, floods and avalanches. In fact, on Monday, the rain / snow limit will rise above 2,500 meters, partly melting the snow that fell in abundance on Sunday between 1,500 and 2,500 meters. This very sudden snowmelt will cause very important hydrological reactions of the tributaries of the Garonne and Adour as well as the combined Gaves.

In addition, the wind will blow like a storm during the night from Sunday to Monday over the Pyrenees, with gusts close to 130 km / h near summits and 100 km / h in Cerdagne-Capcir, in the Font-Romeu sector. These strong winds will cause snowdrifts to form at high altitudes, increasing the risk of an avalanche which could peak above 2300 meters on Monday.

Observation

This Saturday at 10 p.m., the rains intensify rapidly in the southwest with the arrival of the disturbance in the Pyrenees.

Evolution

Tonight, a disturbance is blocked in the southwest of France where a remarkably durable episode of moderate to heavy precipitation begins.

Sunday, it will rain abundantly all day long in the south of the Aquitaine basin and Occitania with intensities of 3 to 8 mm / h. The rain / snow limit will be around 1500 meters.

In the night from Sunday to Monday, it will still rain so heavily. Aggravatingly, the rain / snow limit will suddenly rise above 2,500 meters. Another aggravating factor is the wind which will blow in a storm at more than 130 km / h in the mountains.

Monday will be a critical day: in fact, precipitation will continue with intensities that are still as marked between 4 and 8 mm / h. The rain / snow limit will be around 2,400 meters, partly melting the snow that fell heavily on Sunday between 1,500 and 2,500 meters.

In addition to the rivers that are likely to react strongly with the contribution of snowmelt due to warm weather and very abundant precipitation up to 2400 meters on Monday, the avalanche risk will become high and could lead to the closure of many passes. road.

In the night from Monday to Tuesday, if precipitation begins to weaken with a rain / snow limit which will drop below 1800 meters, the situation will remain under very close hydrological surveillance with floods and undoubtedly very significant floods, which will continue until the middle of next week, despite the return of calm and high pressure.

List of departments concerned