The cold period we experienced between late December and early January could only be a taste of what to prepare for the rest of the winter… Indeed, climatologists have recently noted sudden atmospheric warming in the North Pole region, which could disrupt the usual circulation of westerly winds and soon bring a mass of polar air over Europe.
Should we fear a significant cold spell, when could it occur and what would be the most affected regions? We try to see more clearly in this article.
A “sudden stratospheric warming”
We must analyze the atmospheric situation on the scale of the northern hemisphere to understand the possible consequences on Europe and France. Climatologists have observed that between mid-December and the beginning of January, the temperature of the stratosphere at higher latitudes has dropped from about -70 ° C to -20 ° C.
Usually, the temperature difference between the North Pole and areas further south leads to a westerly wind (the jet stream in English), which provides more or less a temperate winter for Western Europe. When the temperature difference disappears, the westerly current also decreases and nothing retains the cold air from the pole, which then tends to dive towards the south.
This phenomenon of heating which opened the door of the “freezer” is called a “sudden stratospheric warming“(sudden stratospheric warming in English (SSW)). This is not an exceptional phenomenon: the last SSW occurred in February 2018, with a few days of extreme cold and snow in France. The same could well happen for the second half of January.
Still much uncertainty with the ongoing #polarvortex disruption and its impacts but one consistent feature is major vortex center across northern Eurasia with easterly flow to the north. Looks to have the potential to draw #cold Siberian air west towards Northern Europe. pic.twitter.com/gerwDhYQYf
— Judah Cohen (@judah47) January 7, 2021
A clear cooling at the end of January?
As for forecast models for Europe and France in the coming days, the risk of cold is indeed starting to appear. After the softening of Tuesday-Wednesday, temperatures will drop again for the end of this week, with the return of severe morning frosts over the northeast, especially this weekend.
A new softening could take place at the beginning of the following week, but from January 21-22, polar vortex stall signals are becoming clearer over Europe. In other words, a clear cooling could take place for the last ten of January, with temperatures well below the seasonal norms.
The snow could come again in the plains at the end of the month
France would not be spared by this cold weather, and snow could fall again in the plains or at very low altitude. The eastern regions would obviously be at the forefront of this winter weather.
All these indications obviously remain to be confirmed and reliability remains limited for the time being. However, the chances that temperatures will be below seasonal norms at the end of January are getting stronger every day.
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