THE storms with which the Veneto has done the math in the last 24-48 hours causing the banks of some rivers to break in flood after the enormous amount of rain that fell (up to 230-240 mm) has causes very precise that they should occur only rarely but that climate changes have accelerated their frequency: two above all, the disturbance it was unable to move quickly eastwards temporal they continuously drew energy by remaining in the same areas for many hours.
What is “Omega Lock”
Each perturbed front arriving from the west has its own natural evolution in moving towards the east (it is called zonal flow): it rains, yes, but then it passes more or less quickly unless there is a mountain barrier to hinder it. In the case of Veneto, however, things went differently with the remaining atmospheric situation blocked. “In a block configuration, the low pressure is unable to transit towards the east and free the territory, it remains blocked and the phenomena persist for longer in small spaces, producing more intense and extensive rainfall. How did it happen”, explains to Courier The meteorologist Vicenza Marco Rabito (of Meteoveneto.it) talking about the bad weather that especially hit the areas of Padua and Vicenza. This is the “block at Omega” caused by an area of high pressure over Scandinavia and a disturbance over Eastern Europe they create “a central anticyclone with two low pressures on its flanks” (hence the name Omega as the letter of the Greek alphabet).
What are self-healing storms
The other reason why a huge amount of rain fell on small areas is due to self-healing storms that are born”by a convergence of the wind on the ground. On Wednesday we had a south-easterly wind from the Adriatic, warm and humid, and drier currents from the Apennines. At the point where they converge, they rise and generate clouds – explains the expert – “The self-regenerating continues to regenerate itself in a short time, in the Venetian case in a corridor of 15-20 km from Lower Veronese to Lower Padua, and then in the Vicenza area”.
The other causes of extreme bad weather
To the concomitance of these factors we add that thesea water it is already very hot for the period: in similar conditions it is all “fuel” for the clouds that are generated and give rise to violent and persistent phenomena. The atmosphere has much more latent water vapor that “ignites” when there is the right “fuse” to trigger it. The expert recalls that on average over 100 mm fell on the plains, of which 70 mm in just 50 minutes yesterday morning considered “a quantity that is not manageable“. To these must be added the almost 200 mm that fell in the mountains with enormous problems for all the rivers, main and secondary, due to the excessive water flow.
“The exceptionality it lies above all in the frequency with which these phenomena occur. Three months after the event in Vicenza, Verona and Padua, here’s another one. According to statistical models, it should have happened over a longer period of time, but here it is. The climate has changed, the atmosphere increasingly highlights characteristics capable of generating significant phenomena”, adds Rabito.
Zaia: “A new phenomenon”
“The forecasts required us to tell citizens to be cautious on the local front. Our forecasting models worked“, declared this morning the president of the Veneto Region, Luca Zaia, taking stock of the bad weather situation in Veneto with the press at the Regional Civil Protection headquarters. “We are faced with a new phenomenon – underlined Zaia – we don’t know if it happens every time 300 years, as the University of Padua says, but it happened to us. The climate is changing.
The idea of these storms with large precipitations and strong intensity gives a perception of something we have never seen.”
