January 25, 2022

Weather Alert: Winter offensive, snow to the plains

Through Gilles MATRICON, meteorologist

Complete weather forecasts live by phone at

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From Saturday November 27 at 6:00 p.m. to Sunday November 28 at 12:00 p.m.

Situation

Already subject to the presence of a mass of cold air since the beginning of the week, the hexagon is suffering this weekend and until Monday from polar air and moderately active disturbances from the British Isles.

With the direction of the wind to the north, the cold is accentuated and the snow falls temporarily to the plain between the northeast and the center-east. More generally, this first real winter offensive brings a lot of snow from the low altitude on all the massifs (Pyrenees, Alps, Massif Central, Jura and Vosges) from 500 to 600 m.

These snowfalls can descend lower, around 300 or 400 meters on Sunday morning, then again on Monday morning, that is to say at the coldest time of the day.

This winter episode will decrease in intensity on Monday, before giving way to warm weather on Tuesday.

We expect during this episode:
– 2 to 6 cm of snow on the plains of the Grand-Est
– 5 to 15 cm of snow from 500 m in the Vosges, the Jura, the Northern Alps, the Massif Central and 700 m in the western Pyrenees and up to 40 to 80 cm around 1000 m altitude depending on the massifs and slopes.
– snowdrifts on all terrain due to the strong wind
– an avalanche risk which will become strong in the west of the Pyrenees and the north of the Alps from Sunday evening

Observation

This Saturday

At 6 p.m., While the weakening of the wind continues near the English Channel, the air mass continues to cool over France and precipitation, in the form of rain or mixed snow occurs from 400 to 700 meters over the west of the Massif central and the northern Alps as well as on the west of the Pyrenees.

At 3 p.m., the wind is starting to weaken on the whole of the Channel coast, despite some strong occasional gusts at Barfleur (113 km / h) and Fécamp (118 km / h). We no longer exceed 100 km / h elsewhere. Regarding precipitation, it is generally low, in the form of snow above 600 meters over the west of the Massif Central and the Pyrenees.

At 12 noon, the wind is still blowing in a storm on the northern coasts of Brittany with gusts exceeding 100 km / h with 114 km / h at the Pointe du Raz and 107 km / h at Brignogan. These strong winds reach Calvados with 100 km / h in Port-en-Bessin.

Regarding precipitation, it is lull with less snow showers north of the Seine. As temperatures are positive everywhere in the plains, the few snow showers still observed no longer whiten the soils.

Finally near the Pyrenees, precipitation is increasing, especially in the Basque country where it has already fallen 35 mm of rain since last night.

At 9 a.m. the disturbance stretches from the southwest to the eastern borders, bringing a little rain and a few flakes above 400 meters over the Grand Est, Bourgogne Franche-Comté and Rhône-Alpes. Behind the disturbance, a very active limit crosses northern France, causing strong winds near the English Channel, with gusts reaching 135 km / h at Brignogan (29), 111 km / h at Barfleur (50 ), 109 km / h at Fécamp (76) and 101 km / h at Dinard (35). Below this unstable limit, heavy showers occur, mixed with snow on the Perche, the country of Bray and the hills of Artois, temporarily whitening the ground above 150 to 200 meters of altitude.

Monthly wind records were broken with 102 km / h in Lannion (22), 109 km / h in Saint-Cast-le-Guildo (22) and 115 km / h in Sibiril (29).

Finally, near the Pyrenees and in the south of Aquitaine, the rains are clearly increasing with a rain / snow limit of around 900 meters.

Yesterday friday
At 6 p.m., the disturbance from the British Isles stretches from the north of the Loire to the Ardennes, being more active north of the Seine. Between the Ardennes and Champagne, above 400 m, we observe some snowfall at temperatures of 2 to 3 ° C. Elsewhere it is rain, but with the onset of the drop in temperatures, sleet showers are occurring in places along the Channel coast. A thunderstorm of cold air was even observed towards Caen (Calvados). Along the coast, the wind turned to the north-west sector, strengthening and reaching in places 80 km / h.

A 12 h, the rainy disturbance from the British Isles concerns the regions bordering the Channel, from Brittany to Hauts-de-France, and is directed towards the north of Ile-de-France and Champagne-Ardennes. The weather remained cold, but the positive temperatures did not allow the development of snowfall. It is generally 4 to 11 ° C, with 6 ° C in Paris and Caen (14) and 11 ° C in Finistère.

A 9 h, light frosts are frequent at the beginning of the morning from the Grand-Est to the Massif Central. In the direction of the disturbance, which is currently crossing England, the air is less cold with 2 ° C to 7 ° C under a fairly cloudy sky. She is heading quickly for the Channel coast. The temperatures are mild over England, because the air mass is maritime (from 4 ° to 8 ° C this morning in the rain).

Evolution

Tonight
With the direction of the wind to the north and the persistence of showers, the rain-snow limit drops again in the north and the center-east of the country and sometimes favors the bleaching of the soils, in particular towards the Belgian border. and Luxembourgish. On the west of the Pyrenees, continuous rainfall of moderate intensity is increasing, accompanied by a blizzard above 1000 meters in the mountains.

Tonight

A new pluvio-snow front descends from Hauts-de-France to the Ardennes to Lorraine towards Limousin and Burgundy, reaching the north of Auvergne Rhône-Alpes. The heights of the Ardennes, the Lorraine plateau, Limousin from an altitude of 300 meters as well as the north of Auvergne-Rhône-Alpes suffer from small snowfalls holding on to the ground from 400 meters. At the same time, continuous rainfall of moderate to strong intensity continues over the west of the Pyrenees with a blizzard above 900 meters above sea level. Moderate to heavy rains concern the Somme and Pas-de-Calais.

Sunday morning

Snowfall continues above 300 to 400 meters in eastern and central France. They are quite marked in the Jura, the north of Auvergne and the Alps, with a risk of the snow temporarily holding onto the ground until in the valleys a little above Annecy, Dole, Chambéry or Grenoble and Saint- Etienne.

On the west of the Pyrenees, by orographic blocking effect, the sustained rains are maintained, with abundant snowfall from 500 to 600 meters above sea level. Finally in the far north of the country, in Pas-de-Calais, the small return of occlusion causes marked rains.

Sunday afternoon and evening, snowfall will continue on all mountain ranges, above 400 to 500 meters only. In the plains and in the valleys, the positive temperatures will limit the resistance of the snow to the ground.

In the night from Sunday to Monday and Monday morning, snowfall will begin to weaken in the east and in the center of the country, but due to the drop in temperatures, ice will appear as far as the plains and in the valleys. Near the Pyrenees, it will continue to snow moderately, from an altitude of 600 meters on average.

We expect during this episode:
– 2 to 6 cm of snow on the plains of the Grand-Est
– 5 to 15 cm of snow from 500 m in the Vosges, the Jura, the Northern Alps, the Massif Central and 700 m in the western Pyrenees and up to 40 to 80 cm around 1000 m altitude depending on the massifs and slopes.
– snowdrifts on all terrain due to the strong wind
– an avalanche risk which will become strong in the west of the Pyrenees and the north of the Alps from Sunday evening

List of departments concerned