AND flood emergency again in Emilia-Romagna after the two tragic floods of 2023. The cyclone Boris has poured a lot of water into the area strong wave of bad weather with rainfall that yesterday even exceeded 200 millimeters on the Apennine side. Between Wednesday 18 September and Thursday 19 September torrential rains caused numerous floods which have mainly affected the area of Faenzawhere the water reached the first floors of the houses. A Cotignola (RA) the Senio has reached record levels, so much so that a section of the embankment collapsed and the surrounding areas were flooded; Modigliana (FC) the watercourses that cross the town have overflowed, causing extensive flooding. Other rivers and streams that have overflowed are the Sheep in Forlì, the Sillaro in the province of Rimini, theIndex in the province of Bologna, the Lamone and the Marcheno.
I am thousands evacuatedwith over 1000 people spending the night in reception centres (around 800 in the Ravenna area and over 160 in the Bologna area). The Fire Brigade was involved in over 500 interventions especially in the province of Ravenna. The schools remained closed in the provinces of Ravenna, Forlì, Cesena, Rimini and in the metropolitan city of Bologna; rail traffic was also suspended in many provinces.Weather Alert of the Civil Protection remains red in Romagna and in the Bologna area, even if fortunately according to the forecasts the intensity of the bad weather should decrease starting from this afternoon.
The bad weather has also violently affected the Marchewith over 300 interventions of the Fire Brigade especially in the area of Ascoli Piceno where floods have occurred and Ancona where it floodedAsp and a landslide forced the evacuation of 6 families in Osimo.
The meteorological dynamics of floods in Emilia-Romagna
One of those responsible for the bad weather emergency in Emilia-Romagna is the cyclone Boris. Like any cyclone, it is a closed region characterized by low pressure and winds rotating around the depression center. It is the same cyclone that in recent days has devastated Central and Eastern Europe causing one of the most extreme weather events in decades on the continent, with widespread flooding in the Czech Republic, Slovakia, Hungary, Austria, Poland, Romania and Germany and a toll that currently stands at 21 victims.
Boris was formed in Northern Mediterranean due to acold air injection coming from Scandinavia. The low pressure vortex then moved into central Europe, where temperatures were well above average. The contrast between the depression area and the high temperatures on the ground produced a disturbance that hit large areas violently starting on September 12. Part of the reason why Boris caused so much damage is the fact that the cyclone remained “trapped” between two anticyclones (i.e. areas of high pressure): one to the North that is stationed over Scandinavia and the African anticyclone to the South. This blocking situation makes Boris move very slowly, allowing it to discharge its energy for prolonged periods of time over the same areas.
As regards the situation in Italy, the descent of Boris has caused a confluence of two different and contrasting currentsone descending from the north-northwest and one from the east-northeast. These currents, once they collided on the ground, had no alternative but to rise in altitude, where they formed convective cells and therefore storm cloudsThis line of showers remained almost stationary not only because of the blocking of Boris on a larger scale, but also because the Apennine reliefs prevented it from moving.
This is the perfect recipe for heavy and prolonged rainfall. To make matters worse, there is thethermal energy supplied by the AdriaticSince July the sea temperature has been continuously and decidedly above average. This excess heat injected energy into the storm system, “doping” it and making it more energetic than it would have been without the proximity of the shower line to a warm sea.
The role of climate change
This last point should be enough to refute any possible argument of the type “it’s cold so there’s no global warming”: the violence of the events in Emilia-Romagna is also due to the fact that the Adriatic Sea has accumulated excess heat in recent months and the torrential rains of the last few hours are the result of this “doping”, without taking into account the upstream fact that Boris was formed precisely because of the high temperatures of the Mediterranean.
At the moment it is still too early to understand if and to what extent the events of September 18 and 19 in Emilia-Romagna were caused by climate change, but one thing is certain: one of the effects of global warming is precisely the increase in the frequency and intensity of extreme weather events. Floods like those that devastated Emilia-Romagna in 2023 have very long return timesand yet in the last few hours they have occurred again after only 16 months.
