Weather Alert: Nelson Depression: strong gale, intense rain and risk of submersion

From Wednesday March 27 at 6:00 p.m. to Thursday March 28 at 6:00 p.m.

Situation

France is located in a strongly depressed context linked to the deepening of a depression named Nelson on the British Isles, up to 955 hPa. It brings lastingly turbulent weather to a large part of the country with a succession of disturbances for this weekend.

Observation

The event will begin in the evening in the northwest as the stormy cold front passes, with sudden heavy showers and strengthening winds.

Evolution

This Wednesday evening, the wind strengthens significantly in southern Brittany, with gusts reaching 100 to 110 km/h on the coasts of southern Brittany and the Loire-Atlantique coast. Heavy rain affects the departments placed at level yellow until the end of this Wednesday evening. The swell is strengthening offshore with seas becoming very rough.

During the night from Wednesday to Thursday, the wind calms down in Brittany. However, the wind strengthens quickly from the Loire region to the Charentes with gusts of up to 110 km/h there also by the sea.

Thursday morning, the wind strengthens again on the Breton tip with gusts up to 100 to 110 km/h. Strong gusts also affect the Vendée until midday under heavy showers. The sea is clearly choppy in the Mediterranean with a risk of submersion on the coasts of Provence linked to the strong southwest wind. Indeed, a swell of 3 to 4 m will suddenly circulate between Corsica and the continent between late night and mid-morning, potentially causing strong waves on the coastlines facing the southwest.

Thursday afternoonconditions become less degraded over the hours over Brittany and the Atlantic arc while the swell strengthens near the southern coast of Corsica with waves of 3 to 5 m.

In total for the episode, we expect:
– gusts of 100 to 110 km/h, even 120 km/h on exposed capes
– cumulative precipitation of 40 to 60 mm, up to 70 mm on the hills of the Monts d’Arrée and the Montagne Noire on the southern slope.
– a swell of 8 to 9 m off the coast of Finistère, 3 to 4 m in the Mediterranean

List of departments concerned