January 23, 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 Sunday November 28 at 9:00 a.m. to Monday November 29 at 9:00 a.m.

Situation

The hexagon, located under the influence of a vast low pressure system encompassing most of Europe, suffered polar air and moderately active disturbances from the British Isles until Monday.

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 m.

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

In the far North, in the Nord-Pas-de-Calais, a return of occlusion causes lasting rains with 50 to 80 mm of water in 24 hours, which can lead to some reactions of rivers and risks point flooding near low points.

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 Center-Est and Grand-Est
– 5 to 20 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 at around 1000 m altitude depending on the massifs and slopes.
– snowdrifts on all reliefs 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 Sunday

At 9 a.m., light to transiently moderate snowfall occurred from Limousin to Auvergne-Rhône-Alpes up to Burgundy, Franche-Comté, southern Alsace and the Lorraine plateaus. above 300 to 400 meters. The snow temporarily holds on to the ground around 350 meters on average, near Saint-Chamond in the Loire for example. A very light dusting concerns the Nancy region. But it is really from 500 to 600 meters that the snow cover becomes significant with 5 cm. In the Pyrenees, it snows above 600 meters.

Since yesterday, the accumulations of fresh snow have reached 50 cm at Barèges (65) and Cauteret (65) located around 1100 meters above sea level and 40 cm near Laruns (64) at 700 meters above sea level. These snowfalls are therefore very significant and continue.

Finally in the far North, it rains abundantly with 47 mm of rain recorded in Fiefs (62) since yesterday, which corresponds to 2 weeks of precipitation that fell in less than 24 hours.

Evolution

This 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 as far as Franche-Comté, with this snow temporarily holding on to the ground up to the valleys a little above Annecy, Chambéry, Dole, Besançon or Grenoble and Saint-Etienne.

On the west of the Pyrenees, by orographic blocking effect, sustained precipitation is maintained, with abundant snowfall from an altitude of 600 meters. Finally in the far north of the country, in Pas-de-Calais, the small return of occlusion causes marked rains.

This afternoon and tonight, 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 Center-Est and Grand-Est
– 5 to 20 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 at around 1000 m altitude depending on the massifs and slopes.
– snowdrifts on all reliefs 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