This Friday morning, temperatures are freezing on the snowy grounds of Nord-Pas-de-Calais with -10°C in Bourthes in Boulonnais. At the same time, a very mild air mass still affects the Mediterranean regions and in particular Corsica where we flirt with 20°C near Bastia.
For several days, France has been in a conflict zone between cold air of polar origin which affects the far north of the country and much milder air of oceanic origin which invades a large southern half of the country. France. This morning, the temperature differences are exacerbated by two phenomena: the presence of snow on the ground with a clear sky over Nord-Pas-de-Calais and a strong southwest wind which causes temperatures to rise due to the Foëhn effect on the eastern part of Corsica. As a result, the temperature fell locally to -10°C in certain very sheltered areas of Pas-de-Calais while 19°C was recorded in the Bastia region.
Severe frosts in Nord-Pas-de-Calais © The Weather Channel
When the ground is snow-covered and the sky is clear at night with very weak wind, we observe amplified nocturnal radiation with temperatures which drop significantly more than in the absence of snow. The presence of snow on the ground is therefore an important element to take into account when forecasting minimum temperatures. When a polar air mass is present, we are not immune to breaking cold records.
Influence of snow on the ground on temperatures © The Weather Channel
At the other end of the country, the west to southwest wind which blows strongly over Corsica and sweeps over the Bastia region, causes a foëhn effect with an increase in temperatures linked to the compressed air mass. . This is what happened at daybreak with 19°C recorded in Bastia, a temperature 14°C higher than the seasonal norm since it is on average 6°C at daybreak at this time of day. the year.
Foehn effect © The Weather Channel
The direction and strength of the wind is therefore an important element to take into account in regions located near reliefs. Temperatures can be exacerbated by the Foëhn effect and sometimes lead to records for mildness or heat being broken.
Great mildness in the north of Corsica © The Weather Channel
France
