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Monday October 21 at 9:00 a.m. au
Monday October 21 at 5:00 p.m.
Situation
Storm Ashley sweeps across the British Isles. The associated disturbance, powered by a powerful jet stream and an atmospheric river from the Tropics, undulates over the neighboring regions of the English Channel, from Brittany to Hauts-de-France until Monday evening.
Rainfall accumulations are expected to be significant, between 20 and 40 mm on average up to 60 mm, corresponding to 2 to 3 weeks of precipitation in the month of October. These rains occurring on soils saturated with moisture linked to repeated precipitation since the beginning of this autumn can create risks of overflow or occasional flooding.
An aggravating phenomenon, at this time of year corresponding to the All Saints’ Day holidays, are the trees that are still leafy and provide protection from the wind. Falling leaves linked to rain and wind can make roads very slippery and block sewer outlets, increasing the risk of flooding.
Finally, trees, made fragile by repeated rains, can fall more easily to the ground, as was the case in Paris last Thursday.
Observation
This Monday morning at 8 a.m., the disturbance continues to undulate from Brittany to Normandy, giving regular rains. The rains are getting heavier in Nord-Pas-de-Calais. Over the last 24 hours, 32 mm fell in Coray (29) or Ploerdut (56), 30 mm in Merdrignac (22) or Plouay (56), and 21 mm in Quimper (29).
Evolution
This Monday afternoon, while Finistère returns to drier weather with the evacuation of the disturbance, the rains increase from Normandy to Hauts-de-France.
This Monday evening, Brittany and Upper Normandy return to dry weather. On the other hand, the heavy rain episode reaches its peak from Upper Normandy to Hauts-de-France. From 9 p.m., the front will evacuate towards Belgium and this alert can be lifted.
