Storm Alex – France and Italy hit by devastating floods

South-eastern France and north-western Italy have been hit by devastating floods as a result of strong winds and torrential rain from Storm Alex.

Roads, bridges and homes have been destroyed in a number of villages north of Nice in France, where the army has been deployed to help tackle the worst floods for decades.

Meteorological agency Météo-France said that Storm Alex had caused an “exceptional Mediterranean episode” in the Alpes-Maritimes. The torrential rains, locally reaching 500 liters per square meter, caused devastating floods in the Var and related rivers.

The storm made landfall in Britain on the night of 1 to 2 October before heading to the Bay of Biscay.

The French national weather forecaster said that exceptional, even unprecedented, accumulations of rain were recorded.

The Alpes-Maritimes department was placed on red “rain-flood” vigilance on Friday at 6 am –Météo-France said 560 million tons of water had fallen in the region during the space of a few hours, with record amounts of rainfall measured:

• 500.2 mm in Saint-Martin-Vésubie in 24 hours, a little over three months of rain. The level constitutes an absolute record for the resort and for the whole of the Alpes-Maritimes department.
• 380.4 mm in Andon, the equivalent of 2.5 months of October rains
• 355.2 mm in Clans, the equivalent of 3 months of rain
• 335.5 mm at Coursegoules, i.e. 2 months of rain,
• 319 mm at the Mas, or 2 months.
• 271 mm in Breil-sur-Roya, i.e. 2 months.
• 199 mm in Sospel, or 1 and a half months of rain
• 178 mm in Caussols, or 1 month of rain.

The storm’s  vast low pressure complex continued to affect France and in particular North Brittany and the South West over the weekend which were hit by heavy accumulations of rain.

Twenty people are currently listed as missing in France, while Italy has two confirmed fatalities.

Climate change: increasingly frequent and intense episodes

According to Météo-France, the analysis of extreme Mediterranean rainfall events over the past decades highlights an  intensification of heavy rainfall  (+ 22% over the annual maximum daily accumulations between 1961 and 2015) and an  increase in the frequency of the strongest Mediterranean episodes , especially those exceeding the threshold of 200 mm in 24 hours.

Analysis applied to regional climate projections indicate an increase in the intensity of intense precipitation over the northern part of the Mediterranean Basin

Italy’s Piedmont region was particularly badly hit, together with the north-western regions of Lombardy and Liguria.

Venice, where the Mose flood barrier system was recently declared fully operational, was successfully protected from flooding. The city had been prepared for high water levels following storms in August this year.