Weather Alert: Orange alert for floods and floods, gale to the north

From Wednesday, November 15 at 12:00 p.m. to Thursday, November 16 at 10:00 p.m.

Situation

The Haute-Savoie department has returned to orange flood alert because the weather conditions are clearly improving and the decline of the Arve is widespread. The flood was exceptional in connection with the very heavy rain that fell on Tuesday. 153 mm fell over the entire rainy episode in Vallorcine (74), i.e. more than a month of rain in 36 hours, to which is added the melting of the snow.

Pas-de-Calais returned to orange alert level after the 4th exceptional flood of the Liane which occurred Tuesday evening and into the night. Very heavy showers occurred on Tuesday afternoon, particularly in the Bainghen sector where an additional 56 mm fell, bringing the cumulative rainfall from November 1 to 13 to 354 mm. This corresponds to 6 months of rain in Paris. La Canche, l’Aa, l’Hem, la Lys, la Lawe-Clarence remain at level orange.
Charente-Maritime and Vendée are kept on orange alert for floods and floods for the rivers of the Sèvre Niortaise and the Charente.
In the center-east, four departments (Haute-Savoie, Savoie, Isère and Drôme) are placed on orange alert in connection with the flooding of rivers coming down from the mountains and spreading towards the Rhône valley.

On Thursday, a depression coming from the Atlantic will circulate between the English Channel and the north-east of France. It will cause further rain as it passes, particularly in Nord-Pas-de-Calais, which has been hit hard since November 3 by repeated flooding. It will also cause a classic gale this season between Brittany, Normandy, the Paris Basin and the northeast. Maximum gusts will reach between 80 and 90 km/h inland and 100 to 110 km/h on the most exposed coasts.

Observation

This Wednesday

At 3 p.m., the weather is calm and dry in the middle of the afternoon. Only a few light showers affect Champagne and the Ardennes, allowing the flood to subside. The new disturbance is a little ahead of time and is already approaching Finistère with light rain.

At 12, the weather is calm on the Opal Coast and the hills of Artois with all the rivers in recession. Same generalized improvement for Charente-Maritime, Vendée and the central-eastern departments. The dry weather is conducive to the decline of rivers, except for the Isère in flood between Grenoble and its confluence with the Rhône.

At 8 o’clock, the situation is calm in terms of precipitation with the evacuation of the disturbance towards the Benelux and Central Europe. Only a few very scattered residual showers are still observed on the Jura side. In Haute-Savoie, 153 mm fell over the entire rainy episode in Vallorcine (74), i.e. more than a month of rain in 36 hours, to which is added the melting of the snow. The flood peak occurred at the start of the night from Tuesday to Wednesday on the upstream part of the river but at the end of the night in its downstream part. The decline is now widespread.

Evolution

For heavy rain, floods and floods:

Situation in Nord-Pas-de-Calais
After the heavy showers on Tuesday afternoon, the situation is improving in terms of precipitation with the return of drier weather for Wednesday. After the flood peaks at the start of the night, a slow decline will be able to take place and continue during the day on Wednesday. However, flooding will remain significant, particularly in the Liane watershed.
Further deterioration in the weather is already looming for Thursday with the passage of a more active low pressure system than initially expected. Rainfall accumulations of 15 to 30 mm are expected and locally 40 millimeters on the hills of Artois. A move to red alert is not excluded for certain watercourses.

Location in the central west
The weather becomes dry again this Wednesday with a stabilization or slight decline in the Charente and the Sèvre Niortaise. A new disturbance of low activity will cross Vendée and Charente-Maritime between the end of the night and the morning of this Thursday. Rainfall accumulations will remain low, with no impact on waterways.

Location in the east
The weather conditions are clearly improving this Wednesday with the risk of showers becoming low. According to Vigicrues, most of the rivers in the Jura and the Northern Alps should experience a gradual decline during the day on Wednesday, except for the Rhône where the flood peak will be much later. This Thursday afternoon, further precipitation will occur but the amounts of rain will generally be between 10 and 25 mm on the reliefs. The reactions of watercourses should remain quite limited.

For the gale expected this Thursday :
At the end of the night and morning of Thursday, the depression circulates over the west of the Channel and causes violent gusts of wind on the Breton coasts with 100 to
110 km/h on the most exposed coasts, locally 120 km/h on the islands and capes. Gusts reach 90-100 km/h on the coasts of the Loire and Cotentin regions. In Breton lands, gusts are of the order of 80 to 90 km/h, locally 100 km/h on the heights.
The depression then shifts towards Normandy and Picardy at midday before continuing its course towards the north-east at the end of the day. In the afternoon, the wind will blow in violent gusts (100-110 km/h) on the exposed coasts of Normandy. Inland, on an axis going from Normandy to the Paris Basin to the north-east, gusts will often be between 80 and 90 km/h, locally 100-110 km/h on the reliefs of the north-east.

List of departments concerned