Orange alert in the South-West: what is an “atmospheric river”, at the origin of bad weather? – Free noon

Seven departments in the South-West were placed on orange vigilance this Thursday, December 9 by Météo France in the face of the risks of floods, floods and avalanches. Consequence, according to meteorologists, of an “atmospheric river” which will touch the Pyrénées-Orientales, Ariège, Haute-Garonne, Hautes-Pyrénées, Gers, Landes and Pyrénées-Atlantiques. But what exactly does this term “atmospheric river” mean?

“Atmospheric river”, what are we talking about?

The phenomenon is far from new, as the Meteorologist of Météo France in charge of the Languedoc and Roussillon area Florence Vaysse confirms to us. “It is in fact the literal translation of the English-speaking term Atmospheric river, which designates humid air carried by a rapid and rather rectilinear current.”

In the case of the disturbance which is about to affect the southwest of France, a sort of “wet air highway” has formed between southern Greenland and Spain. “This band is contained to the south by the Azores high and to the north by low pressures from Scotland and Iceland, so it heads straight for the Pyrenees.”

Beware of the risk of avalanches in the Pyrenees

By hitting head-on the low temperatures of the Pyrenees, this disturbance heavily loaded with humidity will lead to heavy and localized rains closely monitored by experts from Météo France. “To put it simply, it’s a bit the same mechanism as during the Cévennes phenomena”, details Florence Vaysse, who also calls on mountain users to be extremely careful.

“The snow will fall in abundance in the Pyrenees. And as we will also have strong variations in temperature, with warming and then a drop in mercury, the risk of an avalanche will be high.” A few days before the school holidays and while the resorts in the Pyrenees benefit from a high level of education, be careful, therefore, if you are planning to go skiing in the next few days.