January 18, 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 12:00 p.m. to Monday November 29 at 9:00 a.m.

Situation

France, 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 and the cold, snow sometimes falls as far as the plain between the northeast and the center-east. More generally, this first real winter offensive brings a lot of snow from 600 m on all the massifs (Pyrenees, Alps, Massif Central, Jura and Vosges).

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

In the far North, in Nord-Pas-de-Calais, a return of occlusion causes lasting rains with 50 to 80 mm of water in 24 hours, or the equivalent of 3 weeks of precipitation. These rains cause the rivers flowing down from the Artois hills to rise and cause some local flooding.

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

Observation

This Sunday

At 11:30 a.m., continuous snowfall of moderate intensity occurred from Franche-Comté to the east of the Rhône, from Haute-Savoie to Isère, to the bottom of the valley, between Besançon, Annecy and Grenoble . This snow temporarily holds onto the ground. In Burgundy and Auvergne, it snows intermittently above 400 to 500 meters, more markedly and continuously above 700 meters with 15 cm of snow in Thiers (63) for example. In the Pyrenees, it is the temporary lull, with less snowfall. In Nord Pas-de-Calais, it rains moderately to heavy in Artois: in Fiefs (62), 60 mm of rain fell in 24 hours, equivalent to 3 weeks of precipitation.

At 9 a.m. light to transiently moderate snowfall occurs 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 afternoon and tonight, snowfall continues on all mountain ranges, above 400 to 500 meters only. On the west of the Pyrenees, by orographic blocking effect, sustained precipitation is maintained, with abundant snowfall from an altitude of 600 meters. In the far north of the country, in Nord Pas-de-Calais, the small return of occlusion causes still heavy rains.

Tonight and Monday morning, snowfall persists in the east and the center of the country, giving a few extra centimeters above 300 to 500 meters depending on the massifs. Due to the drop in temperatures, ice will appear in the plains and in the valleys. Near the Pyrenees, it continues to snow moderately, from an altitude of 600 meters on average. With the accumulation of snowfall, the risk of avalanches becomes high, hence the change to the Orange Hautes-Pyrénées alert level by our services.

In Nord Pas-de-Calais, despite the disappearance of the rains, the high level of the rivers remains high, with the persistence of some overflows and occasional flooding.

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

List of departments concerned