An Arctic air mass is ready to slide over central-western Europe and then hit Italy between Thursday 20th and Saturday 22nd November. A cold outbreak which, according to the main forecast models, will bring a temperature drop of 7-8°C, intense winds and snowfall which in some regions could reach unusually low altitudes for the period. The dynamics foresee the descent of a freezing core from the Scandinavian peninsula, capable of generating a cyclonic circulation over the central Mediterranean.
Snow on the plains in the North: where it could arrive
The most critical day will be Friday 21st, when the combination of very cold air and widespread precipitation will make it possible for snow to appear as far as the plains in part of the North. Experts speak of an atmospheric structure attributable to a winter vortex, with northern currents that will descend from Northern Europe to Italy.
The most exposed sectors, according to the latest estimates, are Lombardy, lower Piedmont, upper Veneto, western Emilia and some stretches of the Po Valley. In particular, the snow level could be between 150 and 200 metres, with local encroachments even lower in the event of intense showers.
In cities such as Cuneo, Asti, Alessandria, Turin, Novara, Varese, Bergamo and Milan, the arrival of snowfalls, sometimes mixed with rain, cannot be ruled out, while further south the situation could involve Piacenza, Parma and Reggio Emilia, where the entry of cold air will be particularly strong.
Flakes are also possible in central Liguria, where the dark north wind could drag air cold enough to allow snowfalls almost at sea level between Genoa and Savona. In the Alps and Pre-Alps, however, snow is practically certain: heavy rainfall is expected above 800 metres, with accumulations that could be significant in some valleys.
The meteorological phenomenon that will make this lowering of snow levels possible is that of the so-called “inversion snowfall”, generated by the rapid transfer of cold air from the upper layers towards the ground due to intense precipitation. The result is large, very wet and spectacular flakes, which however can cause traffic disruption.
Center and South: decreasing temperatures and first flakes on the Apennines
The cold wave will reach the Center and then the South between the evening of November 21st and 22nd. The cooling, although less drastic than in the North, will still be evident: below average values and strong winds are expected, which will accentuate the sensation of cold.
The snowfall will also affect the central Apennines, with flakes from 700 meters and real storms above 900-1000 meters especially between Abruzzo and Lazio. In the South the temperature drop will be felt above all because, until a few days ago, many areas were experiencing unusually mild conditions: here snow will only appear above 1200 metres.
A weekend with a winter flavour
The coldest moment of the Arctic wave will be Saturday 22nd, when Italy will experience temperatures widely below normal with possible night frosts in the plains in the North and unstable conditions in most of the central and southern regions. A weekend, therefore, with a clear winter flavour, with the cold season which – this time – decided to arrive a little early.
A situation which, according to meteorologists, may not end quickly: the “frozen channel” between the North Pole and the Mediterranean could in fact remain active throughout the final part of the month, paving the way for other phases of intense cold and new snowfall at very low altitudes.
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