Disturbance number 5 in December will be fast but intenseand will make its effects felt especially between today (Thursday) and tomorrow (Friday) afternoon. It is a disturbance which due to its characteristics can and has been defined as a storm officially named Tempesta Dionisio. We are, therefore, on the threshold of a significant change, first in the North, then in the Centre-South, with also the genesis of a deep cyclone on our western seas.
Pay particular attention to Friday day because it will be characterized by a notable intensification of the winds, with gusts even over 100 km/h. The colder air flowing in from the north will lead to a general sharp drop in temperatures even below seasonal averages and the return of snow on the Alps and Apennines; in the North the Foehn wind will also reach the plains, causing local and temporary temperature increases.
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 towards Italy between the end of Sunday and the start of Christmas week. The climate will remain coldfully winter, with temperatures even below normal.
The weather forecast for Friday 20 December
Wider clearings in the North-West. Prevalence of clouds elsewhere, with scattered rainfallincluding thunderstorms in the lower Tyrrhenian Sea. From the afternoon it also improves in the North-East and, subsequently, in the central Tyrrhenian regions and in Sardinia. Share neve 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.
Minimum temperatures still generally above freezing; maximums decreasing in the Center and in Sardinia, temporarily rising in the Northern plains, 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.
The weather forecast for Saturday 21 December
Latest rainfall in the early hours of the day in Abruzzo, Molise, Irpinia, Puglia, Lucania, southern Calabria and northern Sicily, already running out during the morning. General tendency to clear, with skies that will become mostly clear or slightly cloudy. Windy day to the Centre-South; attenuating winds in the North and in Tuscany.
Minimum temperatures in widespread and noticeable decline (local and weak frosts possible in the Po Valley) and in maximum decreases in the Po Valley and in much of the Centre-South; fully winter climate with values even below the climatic norm and with the feeling of cold accentuated by the wind.
