After a mild and turbulent weekend, the weather conditions will become wintery over the weekend.
With the wind shifting to the north, temperatures will drop and snow will fall at lower and lower altitudes.
The expected quantities are sometimes significant, a good omen a fortnight before the Christmas holidays.
The yo-yo of temperatures continues… While temperatures are close to seasonal norms this mid-week, a new rise is being prepared for the weekend with the return of the disturbed flow. Then, over the weekend, an anticyclone will set up over the Atlantic, which will have the effect of directing a northwesterly then northerly flow towards France. Polar air will thus descend towards France, causing the mercury to drop.
The other consequence of this change in flow will be on the precipitation side. After the sometimes heavy rains over the weekend, snow will gradually prevail, first at medium altitude. Then, from Sundaythe flakes may fall at very low altitude, or even down to the plains. The quantities sometimes promise to be significant in the mountains, a situation which comes at just the right time a few days before the start of the winter sports season.
Up to a meter of fresh snow in the Pyrenees
The configuration change will take place during the day of SATURDAY with the passage of an active disturbance crossing the country from west to east. It will be accompanied by sustained precipitation with a rain-snow limit of between 1200 and 1800 meters above sea level over all the massifs. The expected accumulations will generally be around 15 to 20 cm in the Vosges, Jura and Auvergne and up to a good fifty centimeters in the Pyrenees and in particular the west of the range as well as for the Alps. from the North.
Sundaya pattern of showers and sleet will set in in the eastern half and as far as the Pyrenees with this time a rain-snow limit located at 300-400 meters. The snowflakes will thus be able to invite themselves into certain valleys. During this day, precipitation will be abundant across the entire Pyrenees chain with an additional 30 to 40 cm expected, so that the weekend accumulation could approach one meter between the Pyrénées-Atlantiques and the Hautes-Pyrénées.
Around twenty additional centimeters are also expected in the Jura and the Northern Alps. With a sometimes powerful north wind and significant quantities sometimes falling on bare ground, particularly in the Pyrenees where the sub-layer is often absent, the risk of avalanches will quickly become significant. The greatest caution is already recommended in the mountains from this weekend.
A limited risk of snow (for the moment) in the plains
If all the reliefs will put on their beautiful winter clothes this weekend, will it be the same for the plain regions? With the polar air coming in from the north of the country, this type of configuration is conducive to snowfall in the plains, like what happened on November 21. However, the air mass that concerns us will have a maritime component. Thus, the cold air will soften significantly as it progresses towards France.
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Often gray and humid weather this week before… the big return of the cold
From Sunday and for the start of next week, precipitation will mainly occur along the Channel, in the east of the country and towards the Pyrenees. If snowflakes may appear occasionally in certain valleys as well as on the first heights such as the Ardennes or the Morvan, the risk of real snowfalls in the plains is, for the moment, not relevant. The next few days will still have to be monitored depending on the evolution of the air mass…
