It will bring notable gusts of wind but, above all, a lot of rain. Storm Ashley, which has deepened in the North Atlantic in the last few hours and will approach the Irish coast this Sunday, October 20, will have notable consequences in the west of France.
Rain on Sunday, and especially Monday
If the heart of the storm will remain a good distance from our regions, they will still be swept by a major disturbance, which Ashley helped to bring up.
As shown in the animation below, built with data from the French Arpege model, the most precise of the models operated by Météo France, a first rainy spell will cross Brittany, Normandy and Hauts-de-France this Sunday. But the bulk of the rainy episode is forecast for Monday.
Note that Sunday’s rainy spell will be accompanied by wind gusts that can exceed 70 km/h on the Breton and Normandy coasts, and often more than 60 km/h inland.
Significant accumulations in Brittany
Between now and Monday evening, this rainy episode is expected to bring between 40 and 60 mm of precipitation over a long strip going from South Morbihan to Flanders, via Normandy. As shown in the image below, which presents the accumulations expected by the German model by Monday evening, the heaviest rains are expected in Morbihan.
Note that certain models (the British and the Swiss, in particular) envisage that the accumulations recorded in the south of Normandy could reach those which will be recorded in South Brittany.
Risks of flooding, even wave-submersion
This highly disrupted sequence is all the more notable as it occurs when the soils of our regions are already saturated with water, and the rivers have relatively high levels. In Finistère, Loire-Atlantique or Seine-Maritime, some are already placed on yellow alert, a sign that their development will need to be monitored.
Furthermore, the swell linked to Storm Ashley will surge as far as Brittany which, added to tides with still high coefficients (103 and 97 this Sunday, 89 and 81 Monday), could cause episodes of wave-submersion. Finistère, Morbihan and Manche are thus placed on yellow alert by Météo France this Sunday. Vigicrues notes that these factors could also increase the risk of overflows in certain estuaries.
