An intense phase of bad weather, caused by aintense depression on the Mediterranean nicknamed “Cyclone Harry”is affecting Southern Italy – above all Sicily, Sardinia And Calabria where until tomorrow, January 20th, thered alert for water and hydrogeological risk – with winds up to 90 km/h in the Strait of Messina and in the Sardinia Channel, storm surges and rain which locally exceeded i 200 millimeters in the province of Catanzaro. In response to the red alert, many areas kept schools closed and were evacuated.
The meteorological explanation of the bad weather in Southern Italy
Weather-wise, Harry is one extratropical depression which developed a cyclonic rotation, within which storm structures were formed which from Tunisia began to move westwards until they reached the major Italian islands. Here, the Harry Depression essentially stopped, because it was blocked by a promontory of high pressure coming from Russia and extending to the Balkans.
At this point we therefore have a mass of hot air (because it has collected air directly from the Sahara) and low pressure which collides with an “opposite” air mass, i.e. cold (Arctic air) and high pressure. The strong thermal contrast is at the origin of the violent instability that is dumping rain on Southern Italy, while the baric contrast (i.e. the pressure difference) is causing the strong winds over the Mediterranean. Winds that lead to the storm surges that are hitting the major islands.
The forecast for the next few days: when and where it will move
For tomorrow, January 20thstrong sirocco winds are expected with gusts exceeding 100 km/h in the Ionian, southern Tyrrhenian and Sardinian Channel. The winds will cause strong storms on a large part of the Sardinian, Sicilian and Calabrian coasts.
Wednesday January 21st the bad weather will gradually move westwards, easing over Sardinia but strengthening in Puglia and Basilicata with instability on the entire Adriatic side, while rainfall and rough seas will continue to persist in Sicily and Calabria.
The situation will have resolved throughout the peninsula on Thursday January 22nd.
