After an overall calm phase, a significant change of the weather situation due to the arrival of an Atlantic disturbance (number 5 of the month), one storm which was renamed Dionysius.
On Thursday the disturbance will affect the North and part of the Center and then also affect the Center-South on Friday, when it will give rise to a deep cyclone in the western seas. Friday 20 December will also be characterized by a notable intensification of the winds which, by the evening, will tend to move from the northern quadrants, following the movement of the center of the cyclone from the Ligurian to the lower Tyrrhenian Sea, with even stormy gusts, over 100 km/h.
The colder air flowing in from the north will cause a sharp temperature drop towards values even below seasonal averages and the return of snow on the Alps and Apennines. The current trend, still rather uncertain, indicates an improvement on Saturday starting from the Centre-North, but only temporary with the possibility that the strong north-western currents at high altitude will convey another cold front between the end of Sunday and the beginning of Christmas week.
The weather forecast for Thursday 19 December
Scattered more or less compact cloudiness throughout the country, with the largest clearings in the middle-lower Adriatic and in the far south. Rain initially between the Ligurian East and upper Tuscany, but gradually extending to the rest of the North, except western Piedmont, Western Liguria and eastern Emilia Romagna. Snowfall in the Alps at initially high altitudes, but decreasing to 800-1000 meters in the evening in the central-western sector. Some rain also in Campania and Tyrrhenian Calabria, extending by the evening to the rest of the Tyrrhenian side and western Sardinia.
Temperature maximums decreasing on the Alps and the North-West. Winds strengtheninginitially southern, rotating from the west or north-west in the evening, with strong gusts in Sardinia.
The weather forecast for Friday 20 December
Wider clearings in the North-West. Prevalence of clouds elsewhere, with scattered precipitation, including thunderstorms in the lower Tyrrhenian Sea. From the afternoon it also improves in the North-East and, subsequently, also in the central Tyrrhenian regions and in Sardinia. Share snow around 600 meters in the eastern Alps, higher in the Central-Southern reliefs, but decreasing to 800-1200 meters in the northern Apennines and Sardinian reliefs.
Temperature minimums still generally above zero; maximums decreasing in the Center and in Sardinia, temporarily rising in the North, more marked in the North-West thanks to the Foehn winds. Strong ventilation in cyclonic rotation around the baric minimum moving from the Ligurian to the Tyrrhenian Sea: possible gusts over 100 km/h on the western seas which will become very rough and locally large.
