Weather alert: High winds and heavy rain expected Thursday

TO Regis CREPE, meteorologist

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From Thursday, April 7, 9:00 am to Thursday, April 7, 10:00 pm.

Situation

A very dynamic westerly current is circulating in troughs and active disturbances over the North Atlantic and Western Europe this Thursday and Friday. The northern two-thirds of France are in the path of these perturbations, driven by a powerful high-altitude jet stream.
If rainfall touches many regions, it is longer and more stable in the western foothills of the Limousin, the Massif Central and the landforms of the east, where precipitation accumulations are expected to be significant, capable of reaching the equivalent of 3 weeks to a month of precipitation by Friday evening.
Snow is abundant at 1800 to 2000 m above sea level and the risk of avalanches will become very important in the high mountains. Another element to watch out for is strong winds this Thursday with gusts of 90-100 km/h on our northwest coasts and 70-80 km/h on the lands of the northern half as the rattled front passes.
This special edition will be extended tomorrow Friday with the passage of a storm depression called Diego causing strong wind gusts from west to northeast (100 to 110 km/h).

Observation

Today at 8 am:

Rain and strong winds are already covering the northern half of France. Wind gusts from the southwest sector are steady, typically 90 to 100 km/h on the English Channel and Atlantic coast (north of the Charente-Maritime) and 60 to 70 kph on land, 80 km/h in places. This is a classic winter storm, but still atypical for April.

We noted the maximum:

116 km/h at the Fécamp semaphore (76)
114 km/h at Cape Gris Nez (62)
112 km/h at Barfleur Lighthouse (50)
108 km/h on the Ile de Groix (56)
104 km/h in Carteret (50)
102 km/h in Boulogne-sur-Mer (62)
90 km/h in Calais (62)
87 km/h in Cherbourg

Domestically, we noted, for example, 77 km/h in Melun (77) and Abbeville (80), as well as, for reference, 100 km/h at the top of the Eiffel Tower in Paris.

Evolution

This Thursday morningWhen the excitement passed, heavy rain and strong gusts of wind swept along the English Channel coast. The latter reach from 80 to 100 km/h, in places 110 km/h in the Cotentin, Boulogne and the Pas de Calais. Inside the country they are about 70-80 km/h, in some places 90 km/h. On the Atlantic coast, wind gusts reach 80-90 km/h on open shores, in some places up to 100 km/h on the islands. An episode of prolonged rains begins on the western foothills of the Central Massif and the eastern reliefs. Snow falls at an altitude of 1600 to 1800 m above the Northern Alps.

This Thursday afternoon, on the coast of the English Channel, behind a cold front, the wind has partially weakened, with gusts up to 60-70 km/h. Conversely, near the Atlantic, it becomes stronger as the perturbation passes. On the most exposed coasts, between the south of Brittany and the Charente coast, wind gusts of 90 to 100 km/h are expected. In the lands of the northern half, the wind blows with strong gusts up to 70-80 km/h. Precipitation increases on massifs exposed to the western wind, with an intensity of 3 to 6 mm/hour. Snow falls heavily at altitudes between 1800 and 2000 m, with very strong winds at altitude, which can cause snowdrifts in areas subject to westerly flow, creating wind slabs and increasing avalanche danger.

This Thursday evening, the English Channel and Atlantic coasts are calm ahead of the arrival of Storm Diego late Thursday evening on Friday. The rainy series will continue on the western foothills of the Central Massif and the eastern reliefs with accumulations reaching 30-50 mm from the beginning of the episode, which is equivalent to 10-15 days of rain.

This special edition will be extended until Friday evening. during the next update, due to the passage of the Diego depression, which will give violent gusts on Friday from the center-west to the north-east. The episode of prolonged rains and snowfalls will also last.

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