Southern Italy is at the center of a new one weather alert: the Civil Protection has in fact issued aorange alert in Calabria and Puglia for thunderstorms, including downpours, local hailstorms and strong gusts of wind. In the meantime, in Molise, Basilicata, Sicily and in some sectors of Sardinia, Campania, Abruzzo, Lazio the‘yellow alert. The rainfall already started yesterday, when it mainly hit Sicily: in the Messina area a self-healing storm downloaded more than 150 mm of rain in an hour and a half, causing flooding, landslides and mudslides in the municipalities of Sant’Alessio Siculo and Forza d’Agrò. Meanwhile, the schools they were closed in most of the municipalities of Calabria, including Reggio Calabria, and in some cities of Salento such as Brindisi.
The cause of this bad weather can be attributed to the formation of a Mediterranean vortex cyclonic in character (therefore characterized by low pressure) in lower Tyrrhenian Sea. A normal phenomenon at the end of summer and autumn, when sea surface temperatures are still high. According to forecasts, the vortex should gradually move eastward, and then reach the Balkans over the weekend.
What is a Mediterranean vortex like the one that hit Southern Italy
What brought the bad weather to Southern Italy, therefore, was a Mediterranean cyclonic vortex originating in the lower Tyrrhenian Sea, which caused the formation of intense thunderstorms. Unlike tropical cyclones, which develop exclusively at low latitudes over ocean basins (i.e. at surface temperatures around 26-27°C and powered exclusively by thermal contributions), Mediterranean vortices can form on smaller basins (like the Mediterranean, in fact) and others middle latitudes.
A fundamental element of Mediterranean cyclones has to do with their training: in addition tothermal energy accumulated over the increasingly warm waters of the Mediterranean Sea, their development may occur as a result of the clash (over the same waters) of one cold, dry air massgenerally coming from the north, with another humid and hotusually coming from the south.
The collision of these air masses causes instability in the cyclonic area, which is causing strong winds, intense thunderstorms also in the nature of a storm and possible waterspouts or tornadoes.
In this specific case, it is the same depression structure which caused the recent floods in Spain, causing DANA to fall to low altitude.
How long will the bad weather last in Italy: the weather forecast
But how long will this bad weather last? According to expert forecasts, the Mediterranean vortex in the next few hours it will gradually move eastwardfirst affecting the south of Puglia and subsequently moving towards the Balkans. However, the central regions will be affected by northern currents drawn towards the center of the Mediterranean depression which will cause an increase in theinstability also on the Adriatic sideespecially involving Abruzzo. Rainfall is therefore also forecast for tomorrow, Friday 17 October, in the southern regions.
In the rest of Italy, however, stable weather will prevail, thanks to the presence of the anticyclone coming from the United Kingdom. After an improvement expected for Saturday 18 October, Sunday 19 will see the arrival of a second cyclone coming from Algeria, which will once again head towards Sicily and Calabria.
