After summer in spring, here comes winter in autumn. The snowfall and freezing phenomena that have affected France since last weekend will continue according to Meteo France at least for the next two nights concerning the 28 departments already placed in orange vigilance for Wednesday.
The fault is a classic “conflict of air masses”, according to the weather engineer Jérôme Lacou, between a descent of cold air from Scandinavia and a softer, oceanic air. The contrast is perfectly illustrated by the -10°C recorded this Tuesday morning in Alsace or Lorrain while it was 11°C in Biarritz.
And it is the meeting point between these two air masses that monopolizes the specialists, with a first disturbance accompanied by freezing rain which will arrive by Brittany at the beginning of the night then spread to the east of the Pays-de-France. -Loire and south of Normandy, then to Ile-de-France, “during the second part of the night”, . Caution is therefore advised for motorists. North of this “band” of freezing rain, snow will take over, in the Cotentin, north of the Paris region but also in Alsace where 10 cm of powder could fall in places.
And it’s not over. During the night from Wednesday to Thursday “a new winter pulsation” from Brittany will take place and will follow the same pattern, with new snows which will mainly be concentrated “between Brittany and the Cotentin” then a possibility of extension. in the Paris Basin and the Grand-Est.
Once these two waves have evacuated, Jérôme Lacou warns that the mornings of Friday, Saturday and Sunday will be “particularly cold”, before a welcome mild spell from Monday.
A phenomenon that becomes rare in December
If we cannot evoke a “cold wave”, this winter offensive in the middle of December is quite unprecedented. “We can speak of a notable cold episode with this Tuesday temperatures across the country averaging 1°C, which represents an anomaly of 5°C compared to seasonal norms”, explains climatologist Matthieu Sorel.
This anomaly of 5°C in December has only been reached on average “five days a year” over the past fifty years but only three times in the last decade: on December 31, 2016, December 29, 2014 and December 12, 2012. This “cold is therefore rare”, paradoxically, in this period of global warming. Moreover, we had not seen snow in Rennes since December 2019, in Brest since December 2010, and in Paris since December 2017.