Nighttime heat levels “exceptional” for the month of November were recorded during the night from Sunday to Monday, according to Météo-France. Particularly in the South-West. The phenomenon is explained by the presence of a “South wind everywhere”, which brings “great gentleness”, “accentuated by the Foehn effect” in the Pyrénées-Atlantiques, Landes and Hautes-Pyrénées, under the influence of the Pyrenean relief.
The Foehn effect, which can occur at any time of the year, occurs when the wind crosses a mountain barrier, and experiences a “significant warming of the air mass”. “This is exactly what we observed last night, where the temperature reached 26.3°C in the middle of the night in Pau”explained Matthieu Sorel, climatologist at Météo-France. It was also 23.6°C in Biarritz, 23.4°C in Tarbes, and 24.4°C in Orthez, temperatures “extremely soft” at this time of year.
The Foehn effect was also observed in Brittany during the weekend. “It was 3°C warmer on the north coast (…) than on the south coast, because this air mass was lifted by the Armorican relief and then came down towards the Emerald Coast “where “nocturnal mildness records” were beaten locally for the period, with for example 15.6°C on the island of Bréhat.
The mild air spread to the northern half of the country on Monday morning with 16.4 degrees recorded in Paris at 6 a.m., 17.5 degrees recorded in Orléans (Loiret), 17.3 degrees in Besançon (Doubs) and 16 degrees in Metz (Moselle) and Nancy (Meurthe-et-Moselle). “A cold front having started to advance from the northwest, the air mass will change during the day and it will often be cooler this afternoon.writes Météo France in its newsletter.
“Anomalies” which are markers of “climate change”
“Air masses like that, for this time of year, are something we don’t see, without climate change”he explained, “We have temperatures well above normal everywhere”15°C in Lille, 16°C in Paris, 17°C in Besançon.
Globally, “we have small cold anomalies” as illustrated by the recent early winter episode, with significant snowfall in the northern half of France last Thursday, and “very large warm anomalies”, “this is indeed a marker of the climate change we are experiencing”underlines Mathieu Sorel.
Related News :