Par
Sebastien Lucot
Published on
Nov 15 2024 at 6:47 am
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The first half of November will not be like the second, weather-wise. While the anticyclone largely dominated with atmospheric pressure still reaching peaks – until 1035 hectopascals ce Thursday November 14, 2024 – very calm weather and desperately gray skies, the centers of atmospheric action in the northern hemisphere will be largely reworked.
At the end of the week, the anticyclone will gradually slide over the North Atlantic. Then, to its immediate west off the coast of North America, a blocked depression will deploy and transport these high pressures to Greenland, thus interrupting the supply of the westerly current usually circulating from the ocean towards the 'Europe.
Close to frost
This change in synoptic will have a direct and concrete impact on the sensitive weather experienced in France. Even if the deadline is still far away with numerous adjustments to be made to the weather modeling for the middle of next week, the trend is towards a loss of polar air coming from much more northern latitudes.
From Tuesday November 19, the vent will move towards the north/northwest sector and bring down temperatures at altitude quite significantly for the season.
This air, of polar origin, will nevertheless cross vast maritime expanses before reaching France and the Channel coasts, softening it. Thus, the thermometer will drop to the level of the cows' floor, but not suddenly. Even more so for the peninsula of Cotentinbordered by a sea that is still quite gentle at this time of year.
Concretely, the mercury will struggle to exceed the 7 to 10 degrees in the afternoon in Manche territory, it could sometimes drop below zero degrees at dawn.
And the snow?
Also on Tuesday, France being located between this anticyclonic barrier to the west and a vast low pressure system over northern and central Europe, a strong wind corridor at altitude will allow the deepening of a depression. “The jet stream would reach 250 to 300 km/h, which favored the deepening of potential low pressure minimums,” informs Guillaume Séchet, forecaster at the head of the Météo Villes website. A first gust of wind is then likely to occur.
At the rear, this deepening will drain more cold air over France, while much milder air aloft will battle to rise from the Iberian Peninsula.
An air mass conflict could therefore take place somewhere in France, around Thursday, probably in the north of the country. A shock of this nature naturally generates a disruption with heavy rain, able to transform into snow on its northern part from the first reliefs, such as the Normandy hills of the South Channel, Orne and Calvados.
The conditional remains in order, if only to hope to observe a few flakes. But in times of climate change, it is increasingly rare to observe this type of winter conditions at this time of year. As a reminder, meteorological winter does not begin until 1is December.
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