Funny month of November! Thursday November 21, 2024, the West of France was under relatively early snow, and this Sunday morning the temperatures there are spring-like. Indeed, this Sunday, November 24 at 9 a.m., the thermometer indicated around 20°C in several resorts in Côtes-d'Armor while it snowed there last Thursday.
Indeed, the North-West of the country found itself on Sunday morning under particularly mild temperatures, which reached between 15 and 20°C from 9 a.m. Côtes-d'Armor, Ille-et-Vilaine and Normandy had temperatures close to 0°C at the same time three days ago.
Here are the temperature differences recorded at 9 a.m. Thursday and this Sunday morning, thanks to Météo France data distributed by Météociel:
The largest differences between Thursday and Sunday were noted in Côtes-d'Armor: Lannion (+ 18.3 °C), Ploumanac'h (+ 17.6 °C), Saint-Brieuc (+ 17.4 °C), Bréhat (+ 16.1)… The same phenomenon occurred all along the Normandy coast and in Hauts-de-France. In Calais and Le Touquet, there is also a difference of more than 15°C.
Angers, Rennes, Caen, Tours, Paris… This large northwest quarter where the snow fell on Thursday is experiencing temperatures rising by 10 to 15°C this Sunday.
These are notable values, but in some regions these variations are daily. The difference between the lowest temperature and the highest temperature is called the thermal amplitude. In Kabul in Afghanistan, the average daily temperature range is 27.3°C with very cool early mornings and hot afternoons.
In France, the record for thermal amplitude over a day was recorded on January 13, 1968. In Mouthe (Doubs), well known for being one of the coldest villages in France, it was -36 that day. .7°C in the morning and 1.1°C in the afternoon. That is to say a thermal amplitude of 38°C.
Foehn effect
The great mildness noted along the Costa Rican coast is due to a slight foehn effect. This meteorological phenomenon occurs when a wind hits a relief perpendicularly. Meteorologist Yann Amice explained the principle to Evening Edition : “The Foehn effect occurs when there is a wind perpendicular to a mountain or significant relief. This air, when it rises on the slope, condenses and becomes saturated. We may have an appearance of clouds. And, once it crosses the summit, and ends up on the other side, it becomes much drier and hotter. The clouds disappear. »
The wind blowing this morning in the Côtes-d'Armor comes from the south and the clouds are blocked by the reliefs of the Armorican Massif, explains meteorologist Stéven Tual on Bluesky:
The southerly winds notably reinforce the mildness in the northern part of the region thanks to the Armoricain Massif. These southerly winds also block the clouds to the south of the terrain. This phenomenon is called the Foehn effect. The sun promises to be triumphant for part of the day over northern Brittany.
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— Stéven Tual (@steventual.bsky.social) November 24, 2024 at 08:50
Temperatures should not rise any higher this Sunday.
Vigilance orange
The weather this Sunday is mixed across the country, and Météo France is forecasting a gale to start the week in the center-east of the country.
The meteorological agency issued an orange vigilance notice for six departments from midnight Monday: Allier, Puy-de-Dôme, Saône-et-Loire, Haute-Loire, Rhône et Loire. The Pyrénées-Atlantiques are already on strong wind orange alert this Sunday until 6 p.m.
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